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MICRO-C A compact 'C' compiler for small systems. Technical Manual Release 2.0 Revised 10-Aug-90 Copyright 1988,1990 Dave Dunfield All rights reserved MICRO-C Page: 1 1. INTRODUCTION MICRO-C is a compact, portable compiler for a subset of the 'C' language which is suitable for implementation on small 8 or 16 bit computer systems. It may be used as a resident or cross compiler, and is capable of generating ROMable code. It is distributed in source form, and thus provides a learning tool for those wishing to examine the internals of a working compiler. The main goal in the development of MICRO-C, has been to provide a reasonably powerful language which will be portable with little difficulty to many target systems. The 'C' language was chosen because it was designed to be portable, and provides ample programming power. MICRO-C provides an alternative to interpreted BASIC or assembly language programming which are often the only languages available on small 8 bit systems. With today's focus on larger computers and workstations, software support for small systems and micro-controller sized devices is getting hard to find. MICRO-C helps fill that gap, because all files necessary to port and maintain the compiler are included on the distribution disk, allowing it to be moved to ANY system without dependance on a software vendor. Sample code generators and runtime librarys are included for several popular microprocessors. Also included with the compiler is the 'C' and 'ASM' source code for a complete library of system functions, as well several example programs. The MICRO-C "package" (software and documentation) is copyrighted, and may not be re-distributed in any form without my written permission. If you have received the "DEMO" archive, and wish to obtain the entire MICRO-C package complete with source code, fill out and send the order form contained in the "READ.ME" file, along with the required payment to: Dave Dunfield 56 Burnetts Grove Circle, Nepean, Ont. (Canada) K2J 1N6 If you choose not to order the complete MICRO-C package, you MUST discontinue using MICRO-C within thirty days. MICRO-C is provided on an "as is" basis, with no warranty of any kind. In no event shall the author be liable for any damages arising from its use or distribution. MICRO-C Page: 2 1.1 Code Portability With few exceptions, this compiler follows the syntax of the "standard" UNIX compiler (within its subset of the language). Programs written in MICRO-C should compile with few changes under other "standard" compilers. 1.1.1 Unsupported Features: MICRO-C does not currently support the following features of standard 'C': Long, Double, Float and Enumerated data types, Structures, Unions, Typedef and Bit fields. 1.1.2 Additional Features MICRO-C provides a few additional features which are not always included in "standard" 'C' compilers: Unsigned character variables, Nested comments, 16 bit character constants, Inline assembly code capability. 1.2 Compiler Portability MICRO-C is written in standard 'C', and is capable of compiling itself. This allows any system with a 'C' compiler (including MICRO-C) to be used to port MICRO-C to another processor. The parser makes very few assumptions about the target processor or operating system architecture, allowing a code generator to be written for virtually any processor and environment. With the exception of required I/O routines (described later), the MICRO-C compiler uses no library functions, and relies on no system services. Assuming that the code generator is fairly efficent, and that the I/O routines and code generator are not unreasonably large, a full MICRO-C compiler may be implemented on systems with as little as 32K of free ram and a single floppy disk. MICRO-C Page: 3 1.3 The MCC command When created using the 'io' routines supplied on the distribution disk, the format of the MICRO-C Compiler command line is: MCC [input_file] [output_file] [options] [input_file] is the name of the source file containing 'C' statements to read. If no filenames are given, MCC will read from standard input. [output_file] is the name of the file to write the generated assembly language code to. If less than two filenames are specified, MCC will write to standard output. 1.3.1 Command Line Options -q - Instructs MCC to be quiet, and not display the startup message when it is executed. MICRO-C Page: 4 2. THE MICRO-C PROGRAMMING LANGUAGE The following pages contain a brief summary of the features and constructs implemented in MICRO-C. This document does not attempt to teach 'C' programming, and assumes that the reader is familiar with the language. 2.1 Constants The following forms of constants are supported by the compiler: <num> - Decimal number (0 - 65535) 0<num> - Octal number (0 - 0177777) 0x<num> - Hexidecimal number (0x0 - 0xffff) '<char>' - Character (1 or 2 chars) "<string>" - Address of literal string. The following "special" characters may be used within character constants or strings: \n - Newline (line-feed) (0x0a) \r - Carriage Return (0x0d) \t - Tab (0x09) \f - Formfeed (0x0c) \b - Backspace (0x08) \<num> - Octal value <num> (Max. three digits) \x<num> - Hex value <num> (Max. two digits) \<char> - Protect character <char> from input scanner. 2.2 Symbols Symbol names may include the characters 'a'-'z', 'A'-'Z', '0'-'9', and '_'. The characters '0'-'9' may not be used as the first character in the symbol name. Symbol names may be any length, however, only the first 15 characters are significant. The "char" modifier may be used to declare a symbol as an 8 bit wide value, otherwise it is assumed to be 16 bits. eg: char input_char; The "int" modifier may be used to declare a symbol as a 16 bit wide value. This is assumed if neither "int" or "char" is given. eg: int abc; The "unsigned" modifier may be used to declare a symbol as an unsigned positive only value. Note that unlike some 'C' compilers, this modifier may be applied to a character (8 bit) variable. eg: unsigned char count; MICRO-C Page: 5 The "extern" modifier causes the compiler to be aware of the existance and type of a global symbol, but not generate a definition for that symbol. This allows the module being compiled to reference a symbol which is defined in another module. This modifier may not be used with local symbols. eg: extern char getc(); A symbol declared as external may be re-declared as a non-external at a later point in the code, in which case a definition for it will be generated. This allows "extern" to be used to inform the compiler of a function or variable type so that it can be referenced properly before that symbol is actually defined. The "static" modifier causes global variables to be available only in the file where they are defined. Variables or functions declared as "static" will not be accessable as "extern" declarations in other object files, nor will they cause conflicts with duplicate names in those files. eg: static int variable_name; The "register" modifier indicates to the code generator that this is a high priority variable, and should be kept where it is easy to get at. Since its interpretation depends on the code generator, it is often ignored in simple implementations. See "Functions" for a special use of "register" when defining a function. eg: register unsigned count; Symbols declared with a preceeding '*' are assumed to be 16 bit pointers to the declared type. eg: int *pointer_name; Symbol names declared followed by square brackets are assumed to be arrays with a number of dimensions equal to the number of '[]' pairs that follow. The size of each dimension is identified by a constant value contained within the corresponding square brackets. eg: char array_name[5][10]; 2.2.1 More Symbol Examples char a; /* 8 bit signed */ unsigned char b; /* 8 bit unsigned */ int c; /* 16 bit signed */ unsigned int d; /* 16 bit unsigned */ unsigned e; /* also 16 bit unsigned */ extern char f(); /* external function returning char */ MICRO-C Page: 6 2.2.2 Global Symbols Symbols declared outside of a function definition are considered to be global and will have memory permanently reserved for them. Global symbols are defined by name in the output file, allowing other modules to access them. Note that the compiler IS case sensitive, however if the assembler you are using is NOT, you must be careful not to declare any global symbols with names that differ only in case. All non-initialized global variables are generated at the very end of the output file, after the literal pool is dumped. Since non-initialized globals do not generate object code, this allows them to be excluded from the image file when it is saved to disk. Global variables may be initialized with one or more values, which are expressed as a single array of integers REGUARDLESS of the size and shape of the variable. If more than one value is expressed, '{' and '}' must be used. eg: int i = 10, j[2][2] = { 1, 2, 3, 4 }; When arrays are declared, a null dimension may be used as the dimension size, in which case the size of the array will default to the number of initialized values. eg: int array[] = { 1, 2, 3 }; Initialized global variables are automatically saved within the code image, insuring that the initial values will be available at run time. Any non-initialized elements of an array which has been partly initialized will be set to zero. Non-initialized global variables are not preset in any way, and will be undefined at the beginning of program execution. 2.2.3 Local Symbols Symbols declared within a function definition are allocated on the stack, and exist only during the execution of the function. To simplify the allocation and de-allocation of stack space, all local symbols must be declared at the beginning of the function before any code producing statements are encountered. MICRO-C does not support initialization of local variables in the declaration statement. Since local variables have to be initialized every time the function is entered, you can get the same effect using assignment statements at the beginning of the function. No type is assumed for arguments to functions. Arguments must be explicitly declared, otherwise they will be undefined within the scope of the function definition. MICRO-C Page: 7 2.3 Arrays & Pointers When MICRO-C passes an array to a function, it actually passes a POINTER to the array. References to arrays which are arguments are automatically performed through the pointer. This allows the use of pointers and arrays to be interchangable through the context of a function call. Ie: An array passed to a function may be declared and used as a pointer, and a pointer passed to a function may be declared and used as an array. 2.4 Functions Functions are essentially initialized global symbols which contain executable code. MICRO-C accepts any valid value as a function reference, allowing some rather unique (although non-standard) function calls. For example: function(); /* call function */ variable(); /* call contents of a variable */ (*var)(); /* call indirect through variable */ (*var[x])(); /* call indirect through indexed array */ 0x5000(); /* call address 0x5000 */ Since this is a single pass compiler, operands to functions are evaluated and pushed on the stack in the order in which they are encountered, leaving the last operand closest to the top of the stack. This is the opposite order from which many 'C' compilers push operands. For functions with a fixed number of arguments, the order of which operands are passed is of no importance, because the compiler looks after generating the proper stack addresses to reference variables. HOWEVER, functions which use a variable number of arguments are affected for two reasons: 1) The location of the LAST arguments are known (as fixed offsets from the stack pointer) instead of the FIRST. 2) The symbols defined as arguments in the function definition represent the LAST arguments instead of the FIRST. If a function is declared as "register", it serves a special purpose and causes the accumulator to be loaded with the number of arguments passed whenever the function is called. This allows the function to know how many arguments were passed and therefore determine the location of the first argument. MICRO-C Page: 8 2.5 Control Statements The following control statements are implemented in MICRO-C: if(expression) statement; if(expression) statement; else statement; while(expression) statement; do statement; while expression; for(expression; expression; expression) statement; return; return expression; break; continue; switch(expression) { case constant_expression : statement; ... break; case constant_expression : statement; ... break; . . . default: statement; } label: statement; goto label; MICRO-C Page: 9 2.5.1 Notes on Control Structures 1) Any "statement" may be a single statement or a compound statement enclosed within '{' and '}'. 2) All three "expression"s in the "for" command are optional. 3) If a "case" selection does not end with "break;", it will "fall through" and execute the following case as well. 4) Expressions following 'return' and 'do/while' do not have to be contained in brackets (although this is permitted). 5) Label names may preceed any statement, and must be any valid symbol name, followed IMMEDIATELY by ':' (No spaces are allowed). Labels are considered LOCAL to a function definition and will only be accessable within the scope of that function. MICRO-C Page: 10 2.6 Expression Operators The following expression operators are implemented in MICRO-C: 2.6.1 Unary Operators - - Negate ~ - Complement ! - Logical complement ++ - Pre or Post increment -- - Pre or post decrement * - Indirection & - Address of (type) - Typecast 2.6.2 Binary Operators + - Addition - - Subtraction * - Multiplication / - Division % - Modulus & - Bitwise AND | - Bitwise OR ^ - Bitwise EXCLUSIVE OR << - Shift left >> - Shift right == - Test for equality != - Test for inequality > - Test for greater than < - Test for less than >= - Test for greater than or equal to <= - Test for less than or equal to && - Logical AND || - Logical OR = - Assignment += - Add to self assignment -= - Subtract from self assignment *= - Multiply by self assignment /= - Divide by and reassign assignment %= - Modular self assignment &= - AND with self assignment |= - OR with self assignment ^= - EXCLUSIVE OR with self assignment <<= - Shift left self assignment >>= - Shift right self assignment MICRO-C Page: 11 NOTES: 1) The expression "a && b" returns 0 if "a" is zero, otherwise the value of "b" is returned. The "b" operand is NOT evaluated if "a" is zero. 2) The expression "a || b" returns the value of "a" if it is not 0, otherwise the value of "b" is returned. The "b" operand is NOT evaluated if "a" is non-zero. 2.6.3 Other Operators ; - Ends a statement. , - Allows several expressions in one statement. + Separates symbol names in multiple declarations. + Separates constants in multi-value initialization. + Separates operands in function calls. ? - Conditional expression. : - Delimits labels, ends CASE and separates conditionals. { } - Defines a block of statements. ( ) - Forces priority in expression, indicates function calls. [ ] - Indexes arrays. If fewer index values are given than the number of dimensions which are defined for the array, the the value returned will be a pointer to the appropriate address. Eg: char a[5][2]; a[3] returns address of forth row of two elements. (remember index's start from zero) a[3][0] returns the character at index [3][0]; MICRO-C Page: 12 2.7 Preprocessor Commands The MICRO-C compiler supports the following pre-processor commands. These commands are recognized only if they occur at the beginning of the input line. NOTE: This describes the limited pre-processor which is integral to the compiler, see also the section on the more powerful external processor (MCP). 2.7.1 #asm Causes the compiler to copy all subsequent lines directly to the output file without translation. This allows assembly language code to be included in the 'C' program. 2.7.2 #endasm Terminates a "#asm", and causes the compiler to resume compiling from the input file. 2.7.3 #define <name> <replacement_text> The "#define" command allows a global name to be defined, which will be replaced with the indicated text whenever it is encountered in the input file. This occurs prior to processing by the compiler. 2.7.4 #include <filename> This command causes the indicated file to be opened and read in as the source text. When the end of the new file is encountered, processing will continue with the line following "#include" in the original file. 2.7.5 #ifdef <name> Processes the following lines (up to #else or #endif) only if the given name is defined. 2.7.6 #ifndef <name> Processes the following lines (up to #else or #endif) only if the given name is NOT defined. 2.7.7 #else Processes the following lines (up to #endif) only if the preceeding #ifdef or #ifndef was false. 2.7.8 #endif Terminates #ifdef and #ifndef NOTE: The #ifdef and #ifndef contructs may not be nested. MICRO-C Page: 13 2.8 Error Messages When MICRO-C detects an error, it outputs an informational message indicating the type of problem encountered. The error message is preceeded by the line number(s) of the line containing the error in all files being processed. eg: 5:3: Syntax error In the above example, the main input file "#included" a file at line 5, and a syntax error was discovered in that file at line 3. The following error messages are produced by the compiler: 2.8.1 Compilation aborted The preceeding error was so severe than the compiler cannot proceed. 2.8.2 Constant expression required The compiler requires a constant expression which can be evaluated at compile time (ie: no variables). 2.8.3 Declaration must preceed code. All local variables must be defined at the beginning of the function, before any code producing statements are processed. 2.8.4 Dimension table exhausted The compiler has encountered more active array dimensions than it can handle. 2.8.5 Duplicate local: 'name' You have declared the named local symbol more than once within the same function definition. 2.8.6 Duplicate global: 'name' You have declared the named global symbol more than once. 2.8.7 Expected '<token>' The compiler was expecting the given token, but found something else. 2.8.8 Expression stack overflow The compiler has found a more complicated expression than it can handle. Check that it is of correct syntax, and if so, break it up into two simpler expressions. MICRO-C Page: 14 2.8.9 Expression stack underflow The compiler has made an error in parsing the expression. Check that it is of correct syntax. 2.8.10 Illegal indirection You have attempted to perform an indirect operation ('*' or '[]') on an entity which is not a pointer or array. This error will also result if you attempt to index an array with more indices than it has dimensions. 2.8.11 Illegal initialization Local variables may not be initialized in the declaration statement. Use assignments at the beginning of the function code to perform the initialization. 2.8.12 Illegal nested function You may not declare a function within the definition of another function. 2.8.13 Improper #else/#endif A #else or #endif statement is out of place. 2.8.14 Inconsistant re-declaration: 'name' You have attempted to redefine the named external symbol with a type which does not match its previously declared type. 2.8.15 Incorrect declaration A statement occuring outside of a function definition is not a valid declaration for a function or global variable. 2.8.16 Invalid '&' operation You have attempted to reference the address of something that has no address. This error also occurs when you attempt to take the address of an array without giving it a full set of indicies. Since the address is already returned in this case, simply drop the '&'. (The error occurs because you are trying to take the address of an address). 2.8.17 Macro expansion too deep The compiler has encountered a nested macro reference which is too deep to be resolved. 2.8.18 Macro space exhausted The compiler has encountered more macro ("#define") text than it has room to store. MICRO-C Page: 15 2.8.19 No active loop A "continue" or "break" statement was encountered when no loop is active. 2.8.20 No active switch A "case" or "default" statement was encountered when no "switch" statement is active. 2.8.21 Not an argument: 'name' You have declared the named variable as an argument, but it does not appear in the argument list. 2.8.22 Non-assignable You have attempted an operation which results in assignment of a value to an entity which cannot be assigned. (eg: 1 = 2); 2.8.23 Numeric constant required The compiler requires a constant expression which returns a simple numeric value. 2.8.24 String space exhausted The compiler has encountered more literal strings than it has room store. 2.8.25 Symbol table full The compiler has encountered more symbol definitions than it can handle. 2.8.26 Syntax error The statement shown does not follow syntax rules and cannot be parsed. 2.8.27 Too many active cases The compiler has run out of space for storing switch/case tables. Reduce the number of active "cases". 2.8.28 Too many defines The compiler has encountered more '#define' statements than it can handle. Reduce the number of #defines. 2.8.29 Too many errors The compiler is aborting because of excessive errors. MICRO-C Page: 16 2.8.30 Too many includes The compiler has encountered more nested "#include" files than it can handle. 2.8.31 Too many initializers You have specified more initialization values than there are locations in the global variable. 2.8.32 Type clash You have attempted to combine values which are of incompatible types. 2.8.33 Unable to open: 'name' A "#include" command specified the named file, which could not be opened. 2.8.34 Undefined: 'name' You have referenced a name which is not defined as a local or global symbol. 2.8.35 Unreferenced: 'name' The named symbol was defined as a local symbol in a function, but was never used in that function. This error will occur at the end of the function definition containing the symbol declaration. It is only a warning, and will not cause the compile to abort. 2.8.36 Unresolved: 'name' The named symbol was forward referenced (Such as a GOTO label), and was never defined. This error will occur at the end of the function definition containing the reference. 2.8.37 Unterminated conditional The end of file was encountered when a "#if" or "#else" conditional block was being processed. 2.8.38 Unterminated function The end of the file was encountered when a function definition was still open. MICRO-C Page: 17 2.9 Quirks In its effort to provide the maximum amount of functionality with the minimum amount of code, MICRO-C deviates from standard 'C' in some areas. The following is a short summary of the major infractions and quirks: The operands to '#' commands are parsed based on separating spaces, and any portion of the line not required is ignored. In particular, the '#define' command only accepts a definition up to the next space or tab character. eg: #define APLUSONE A+1 <-- uses "A+1" #define APLUSONE A +1 <-- uses "A" Comments are stripped by the token scanner, which occurs AFTER the '#' commands are processed. eg: #define NULL /* comment */ <-- uses "/*" Note that since comments can therefore be included in "#define" symbols, you can use "/**/" to simulate spaces between tokens. eg: #define BYTE unsigned/**/char Include filenames are not delimited by '""' or '<>' and are passed to the operating system exactly as entered. eg: #include /mc/stdio.h NOTE: The above quirks do not apply when the external pre-processor (MCP) is used. The appearance of a variable name in the argument list for a function declaration serves only to identify that variables location on the stack. MICRO-C will not define the variable unless it is explicitly declared (between the argument list and the main function body). In other words, all arguments to a function must be explicitly declared. MICRO-C is more strict about its handling of the ADDRESS operator ('&') than most other compilers. It will produce an error message if you attempt to take the address of a value which is already a fixed address (such as an array name without a full set of indicies). Since an address is already produced in such cases, simply drop the '&'. The 'x' in '0x' and '\x' is accepted in lower case only. MICRO-C Page: 18 When operating on pointers, MICRO-C only scales the increment (++), decrement (--) and index ([]) operations to account for the size of the pointer: eg: char cptr; /* pointer to character */ int cptr; /* pointer to integer */ ++cptr; /* Advance one character */ ++iptr; /* Advance one integer */ cptr[10]; /* Access the tenth character */ iptr[10]; /* Access the tenth integer */ cptr += 10; /* Advance 10 characters */ iptr += 10; /* Advance ONLY FIVE integers */ NOTE: A portable way to advance "iptr" by integers is: iptr = &iptr[10]; /* Advance 10 integers */ When using MICRO-C to create a function which will contain assembly language code, remember that MICRO-C allocates all local variables at the beginning of a function definition, and will not generate the function entry code until a non-declarative statement is encountered. In particular, since "#asm" is handled by the pre-processor and not seen as a statement by the parser, you should use a "null" statement (';') to ensure that the entry code is generated prior to using "#asm" at the beginning of a function. eg: func() { ; /* ensures "entry" code is generated */ #asm assembly statements #endasm } Also note, that MICRO-C will not output external declarations to the output file for any variables or functions which are declared as "extern", unless that symbol is actually referenced in the 'C' source code. This prevents "extern" declarations in system header files (such as "stdio.h") which are used as prototypes for some library functions from causing those functions to be loaded into the object file. Therefore, any "extern" symbols which are referenced only by assembly code (using "#asm") must be declared in assembly code, not by the MICRO-C "extern" statement. MICRO-C Page: 19 Unlike some 'C' compilers, MICRO-C will process character expressions using only BYTE values. Character values are not promoted to INT unless there is an INT value involved in the expression. This results in much more efficent code when dealing with characters, particularily on small processors which have limited 16 bit instructions. Consider the statement: return c + 1; On some compilers, this will sign extend the character variable 'c' into an integer value, and then ADD an integer 1 and return the result. MICRO-C will ADD the character variable and a character 1, and then promote the result to INT before returning it (results of expressions as operands to 'return' are always promoted to int). Unfortunately, programs have been written which rely on the automatic promotion of characters to INTs to work properly. The most common source of problems is code which attempts to treat CHAR variables as UNSIGNED values (older compilers did not support UNSIGNED CHAR). For example: return c & 255; In a compiler which always evaluates character expressions as INT, the above statement will extract the value of 'c' as positive integer ranging from 0 to 255. In MICRO-C, ANDing a character with 255 results in the same character, which gets promoted to an integer value ranging from -128 to 127. To force the promotion within the expression, you could CAST the variable to an INT: return (int)c & 255; The same objective can be achieved in a more efficent (and correct) manner by declaring the variable 'c' as UNSIGNED CHAR, or by CASTing the variable to an UNSIGNED value: return (unsigned)c; Note that this is not only more clearly shows the intent of the programmer, but also results is more efficent code generated. MICRO-C Page: 20 3. ADVANCED TOPICS This section provides information on the more advanced aspects of MICRO-C, which is generally not needed for casual use of the language. 3.1 Conversion Rules MICRO-C keep track of the "type" of each value used in all expressions. This type identifies certain characteristics of the value, such as size range (8/16 bits), numeric scope (signed/unsigned), reference (value/pointer) etc. When an operation is performed on two values which have identical "types", MICRO-C assigns that same "type" to the result. When the two value "types" involved in an operation are different, MICRO-C calculates the "type" of the result using the following rules: 3.1.1 Size range If both values are direct (not pointer) references, the result will be 8 bits only if both values were 8 bits. If either value was 16 bits, the result will be 16 bits. If one value is a pointer, and the other is direct, the result will be a pointer to the same size value as the original pointer. If both values were pointers, the result will be a pointer to 16 bits only if both original pointers referenced 16 bit values. If either pointer referenced an 8 bit value, the result will reference an 8 bit value. 3.1.2 Numeric Scope The result of an expression is considered to be signed only if both original values were signed. If either value was an unsigned value, the result is unsigned. 3.1.3 Reference If either of the original values was a pointer, the result will be a pointer. Note that this "calculated" result type is used for partial results within an expression. Whenever a symbol such as a variable or function is referenced, the type of that symbol is taken from its declaration, no matter what "type" of value was last stored (variable) or returned (function). MICRO-C Page: 21 3.2 Assembly Language Interface Assembly language programs may be called from 'C' functions and vice versa. These programs may be in the form of "#asm" statements in the 'C' source code, or separately linked modules. When MICRO-C calls any routine ('C' or assembler), it first pushes all arguments to the routine onto the processor stack, in the order in which they occur in the argument list to the function. This means that the LAST argument to the function is LOWEST on the processor stack. Arguments are always pushed as 16 bit values. Character values are extended to 16 bits, and arrays are passed as 16 bit pointers to the array. (MICRO-C knows that arrays which are arguments are actually pointers, and automatically references through the pointer). After pushing the arguments, MICRO-C then generates a machine language subroutine call, thereby executing the code of the routine. Since the compiler uses the ACCUMULATOR and INDEX REGISTER, it will automatically save them (if necessary) during processing of the arguments to the function (even if no arguments are present), and therefore these registers do not have to be preserved by the called routine. NOTE that any other registers used by the code generation routines (register variables etc) will not be saved by MICRO-C, and should be preserved by called functions if their content is to be relied on between function calls. Once the called routine returns, the arguments are removed from the stack by the calling program. This usually consists of simply adding the number of bytes pushed as arguments to the stack pointer. When the called function executes, the first thing usually done is to push any registers which must be preserved, and to reserve space on the stack for any local variables which are required. In some implementations, a "base" register may also be established to provide a stable reference to the local variables and arguments. It is the responsibility of the called function to remove any saved registers and local variable space from the stack before it returns. If a value is to be returned to the calling program, it is expected to be in the ACCUMULATOR register. MICRO-C Page: 22 Local variables in a function may be referenced as direct offsets from the "base" register or stack pointer. Note that if the stack pointer is used, offsets must be adjusted for the number of bytes which are pushed and popped on the stack during the execution of the function. The address of a particular local variable is calculated as: "base register" - (Size of all local variables in bytes) + (size of all preceeding local variables in bytes) -- OR -- "stack pointer" + (# bytes pushed during function execution) + (size of all preceeding local variables in bytes) Arguments to a function may also be referenced as direct offsets from the "base" register or stack pointer, in much the same way as local variables are. The address of a particular argument is calculated as: "base register" + (# bytes pushed at entry of function to preserve registers etc.) + (Size of return address on stack (usually 2)) + (# arguments from LAST argument) * 2 -- OR -- "stack pointer" + (# bytes pushed during function execution) + (size of all local variables in bytes) + (# bytes pushed at entry of function to preserve registers etc.) + (Size of return address on stack (usually 2)) + (# arguments from LAST argument) * 2 NOTE: The (number of bytes pushed at entry of function) is a function of the code generator, and depends on the particular MICRO-C implementation. Examine some assembly output from the compiler to determine the actual number on your system. MICRO-C Page: 23 If a function has been declared as "register", MICRO-C will load the accumulator with the number of arguments which were passed, each time the function is called. This allows the function to determine the location of the first argument. The address of the first argument passed to a "register" function may be calculated as: (accumulator contents) * 2 + "base register" + (# bytes pushed at entry of function to preserve registers etc.) + (Size of return address on stack (usually 2)) -- OR -- (accumulator contents) * 2 + "stack pointer" + (# bytes pushed during function execution) + (size of all local variables in bytes) + (# bytes pushed at entry of function to preserve registers etc.) + (Size of return address on stack (usually 2)) Global variables exist at absolute addresses and may be referenced directly by name from within assembler programs. Keep in mind however, that MICRO-C uses only the first 15 characters of a symbol's name. Also, many code generators will reduce the size of names even further, often using an algorithm to compress the name rather than simply truncating it. For this reason, it is a good idea to avoid using global symbol names which are longer than 6 or 8 characters if they are to be referenced from within assembly language programs. MICRO-C Page: 24 3.3 Compiling for ROM Assuming the code generator does not use such "nasty" things as self modifying code, the output from the compiler is entirely "clean", and may be placed in Read Only Memory (ROM). The compiler places all initialized global variables in the output file as part of the code image. When the program is stored in ROM, those variables are also stored in ROM, and will not be modifiable. When the program is to be placed in ROM, you may not initialize any variables which you intend to modify later. Those variables must be explicitly initialized by code executed at the beginning of the program. Initialized variables which you do not intend to modify (such as tables etc.) may be initialized in the declaration, and will be permanently saved in the ROM as part of the static code image. The processor stack pointer must be set up before any expressions are evaluated, or any function calls are performed. This may be performed via '#asm' statements. All non-initialized global variables must be located in RAM. The compiler usually outputs all such variables at the very end of the compilation, just after dumping the literal pool. The global variables may be moved to RAM by editing the output file, and placing an appropriate "ORG" statement at the beginning of the globals. If extensive compilation for ROM is being performed, you may want to use a version of the compiler which uses an intermediate output file (see "PORTING THE COMPILER"). This allows a separate code generator to be customized for ROM applications, which will output the appropriate stack setup instructions (this can be done in "def_module()"), and locate the global variables in RAM (this can be done at the end of "def_literal()"). MICRO-C Page: 25 4. PORTING THE COMPILER There are two major goals to accomplish when porting the MICRO-C compiler to a new machine. The first is to make the compiler run in the new environment, and the second is to make it produce code for that environment. These two goals do not always go hand in hand. For example, it may be desirable to implement a CROSS COMPILER which generates code for a different system from that on which it runs. The usual method of porting a compiler to system A when a version of the compiler is already running on system B, is to first create a compiler which runs on system B, producing code for system A. This "new" compiler may then be used to create a compiler which runs on system A. The compiler consists of a module "compile" which contains, the main compiler, input scanner, regular expression parser, and symbol table management routines. This is the "static" portion of the compiler which does not change in different implementations. To create a working compiler, the above module must be compiled and linked with an "io" module and "code" module. The "io" module performs the necessary initialization and I/O to allow the compiler to run in a particular environment (goal #1). The "code" module generates the assembly language output code for a particular environment (goal #2). The compiler uses NO system library functions, and relies on NO system services (other than those used by the "io" and "code" modules). This allows the compiler to be ported to virtually any system. All fixed compiler parameters (such as table sizes etc) are contained in the header file "compile.h". When porting to systems with very limited RAM (less than 64k), you may have to reduce some of these sizes in order to get it to fit. Two additional modules are provided with the compiler. The file "intercg.c", may be linked into the compiler in place of the code generator, and writes a "generic" intermediate file which contains the pseudo operation and type tokens (See Code Generator). The file "genasm.c", may be linked with the regular "io" and "code" routines to produce a utility program which reads the intermediate file and produces the assembly language code for a specific processor. NOTE: If your system makes a distinction between TEXT and BINARY files, the "io.c" routines must be modified for each program so that the intermediate file will be accessed in BINARY mode. All other files are accessed as TEXT. MICRO-C Page: 26 Although this "split" compiling approach is slower than the usual mode of direct assembly language production, it provides several useful capabilities: 1) The amount of ram required to run the "separate" compiler and genasm programs can be considerably less than required to run the "stand alone" compiler. 2) A single parser may be used to generate code for several target systems, by simply running a different version of the "genasm" utility, which is customized for each target. 3) Use of the intermediate file allows distribution of "portable" programs which may be processed by "genasm" for different targets WITHOUT distribution of the source code. 4) A program may be written which processes this intermediate file, and "optimizes" the code. Additional "pseudo operation" codes may be added to the output file if the target processor is capable of operations which the more "generic" MICRO-C output does not utilize. 4.1 The "io" module The "io" module required by the compiler must contain the following function definitions: The function "main()" is called by the operating system when the MICRO-C compiler is executed. It is responsable for parsing any parmeters and command qualifiers, opening the input and output files, performing any other initializations that might be required, and then invoking the function "compile()" with no arguments. The "compile" function is internal to the "compile.c" module, and will never return. For UNIX and other systems which support I/O redirection, "stdin" and "stdout" are often used for the input and output files. The function "exit(rc)" is called when the compiler has finished all processing and wishes to terminate. The value "rc" is a return code: 0 = Success, program compiled without error, -1 = Compile was aborted due to severe errors, n = Compile finished, but had 'n' errors. The function "put_chr(chr, flag)" is passed a character to output, as well as a flag. The flag will always be zero when the character is being sent to the console terminal, or non-zero when the character is to be written to the output file. The function "put_str(*ptr, flag)" is passed a pointer to a zero terminated string, which is to be written to the console or output file as determined by "flag". The function "put_num(number, flag)" is passed a 16 bit number, which is to be written in printable form to the console or output file as determined by "flag". MICRO-C Page: 27 4.1.1 Compiler only routines The following I/O routines are required by the compiler, but not by the "genasm" program. The function "get_lin(*ptr)" is passed a pointer to a character array, and should read a single line from the currently open input file into that array. The manifest definition "LINE_SIZE", found in "compile.h" may be used to determine the maximum line length acceptable to the compiler. Return of a non-zero value indicates the end of file condition. The function "f_open(*ptr)" is passed a pointer to a filename. The new file should be opened, and if successful, the old input file should remain open and be "stacked", so that it can be later returned to. If the file was opened successfully, a non-zero value should be returned. A zero value indicates to the compiler that the file could not be opened. The function "f_close()" is responsible for closing the currently open input file, and returning to the "stacked" previously open one. It receives no parameters. Note: multiple "opens" may be stacked - see the manifest definition of "INCL_DEPTH" in the "compile.h" file. 4.1.2 Genasm only routines The following I/O routine is required by the "genasm" program, but not by the compiler. The function "get_char()" must return a single character from the input file as a 16 bit number with a positive value between 0 and 255. A '-1' is returned for the end of file condition. 4.1.3 Notes on I/O module 1) It is the responsibility of the "put" routines to translate the NEWLINE '\n' (0x0a) character into whatever line termination character(s) are required by the target operating system. 2) If unix "stdin" and "stdout" are not used, it is the responsibility of "main" to display appropriate error messages if the input or output files could not be opened. Refer to the sample "io" modules distributed with the compiler. MICRO-C Page: 28 4.2 The "code" module In order to insure that MICRO-C is portable to virtually any environment, the compiler makes few assumptions about the processor or system software of the target system. The "code" module is relied on to produce all machine instruction and assembler directives written to the output file. The only two real "assumptions" made about the target processor are: 1) It is assumed that the target processor has an "accumulator" register in which all math operations are performed, and that the lower 8 bits of this register may be accessed independantly. 2) It is assumed that the target processor has one "index" register which may be loaded with a 16 bit value, and that memory references may be made indirectly through this register. If the target processor does not support the above features, it may be possible to write a code generator for it using some other features of the processor. For example, if an "index" register does not exist, it may often be implemented using two bytes of reserved memory. The code generation module required by the compiler must contain the following function definitions: The function "do_asm(*ptr)" is passed a pointer to a character string, which it should write to the output file EXACTLY as passed, followed by a '\n' NEWLINE character. This function is used by the "#asm" directive to write directly to the output file. The function "def_module()" is called at the beginning of compilation, before any other code generator functions are called. It is used to output any pre-amble needed by the assembler. The function "end_module()" is called at the very end of compilation, and is the last code generator function called. It is used to output any post-amble needed by the assembler. The function "def_static(symbol)" is passed am index into the compiler symbol tables for a global variable, which is about to be initialized as static storage. The call to this function will be immediately followed by a call to "init_static" or "end_static". The "init_static(token, value, word)" function is passed a token and value, with which it should initialize a single element of static storage. The "word" flag will be non-zero if the value is a 16 bit element. Only the "constant" tokens (NUMBER, STRING, LABEL) need be handled by this routine. MICRO-C Page: 29 The "end_static()" function is called to terminate the definition of static storage. NOTE: "init_static" should not rely on "def_static" being called first, since it is also called immediately following "def_label" to define "switch" tables (See "do_switch"). After the table is defined, the compiler will call "end_static()" to terminate the initialization and set up for the next. The function "def_global(symbol, size)" is called at the end of the compile, once for each non-static global variable which was defined. The "size" paremeter indicates the number of BYTES of memory to be reserved for that variable. The function "def_extern(symbol)" is called at the end of the compile, once for each non-resolved external symbol which was defined. This routine should examine the type of the symbol and output the appriopriate assembler directives to allow it to be referenced in another module. The "def_func(symbol, size)" routine is called to start a function definition. The "symbol" parameter is an index into the compiler symbol tables for the function entry being defined. The "size" parameter indicates how many bytes of memory should be allocated on the stack for local variables. When defining "register" functions, care must be taken that the entry code preserves the contents of the accumulator. The "end_func()" routine is called to terminate a function definition. It should remove anything placed on the stack (including the local variable space allocated by "def_func"), and terminate the function with a "return" instruction. The "def_label(label)" function is called whenever the compiler wants to generate a label in the output file. Each label generated by the compiler is identified by a 16 bit unsigned number. It is up to the code generator to generate a unique label suitable for the target assembler. The "def_literal(*ptr, size)" function is called at the end of the compile, just before non-initialized global symbols are generated. This routine is given a pointer to the compiler's "literal pool", which contains all the character strings occuring during the compilation. The "size" parameter indicates how many characters are in the pool. This pool must be generated in the output file as a string of byte constants. The "call(token, value, type, clean)" function is used to generate a machine language subroutine call to the entity indicated by the "token, value & type" parameters (See later). The "clean" parameter indicates how many entries were pushed onto the stack as arguments, which should be removed following the function call. Note: Since stack entries are TWO bytes in most implementations, the "clean" value must be multiplied by two to get the actual number of bytes to be removed from the stack. MICRO-C Page: 30 The function "jump(label, ljmp)" is called to generate an unconditional jump instruction to the indicated compiler generated label. The "ljmp" flag will be set to zero if the jump references code within the same expression from which it is generated, and non-zero if one or more statements may occur between the jump and the destination label. This allows the code generator to take advantage of "short" jumps if they are available on the target. The function "jump_if(cond, label, ljmp) is called to generate a conditional jump to a compiler generated label. The "cond" value indicates the condition: FALSE = Jump if accumulator is zero, TRUE = jump if accumulator is non-zero. Remaining parameters are the same as above. The function "do_switch(label)" is passed the address of a "switch" table, which contains 16 bit entries, and is of the following format: label-1, value-1, label-2, value-2, .... label-n, value-n, 0, default_label This routine should search the table for the value currently in the accumulator, and if found, it should proceed to the label associated with that value. If the value is not found before the end of the table is encountered (identified by a label value of zero), execution should proceed at the address identified by "default_label". The "index_ptr(token, value, type)" routine should load the index register with the value of the entity indicated by the "token, value & type" parameters. This will always be a 16 bit wide quantity. The "index_adr(token, value, type)" routine should load the index register with the 16 bit address of the symbol represented by "token, value & type". The routine "expand(type)" is called following the evaluation of expressions in "return" and "switch" statements, and is used to insure that the result is a 16 bit value. The routine "accop(oper, type)" is called to perform a "no operand" operation on the accumulator. See "compile.h" for a list of these operations. The "type" passed indicates the type of value expected as a result. The routine "accval(oper, rtype, token, value, type)" is called to perform a "one operand" operation on the accumulator. See "compile.h" for a list of these operations. "rtype" indicates the type of value expected as a result. "token", "value" and "type" indicate the location and type of operand which is being processed. MICRO-C Page: 31 4.2.1 Notes on code generation The meaning of the individual bits in the 16 bit "type" value which is passed to many of the code generation routines, is documented in the "compile.h" file. The meaning of "token" is documented in the "compile.h" file. For each type of "token", "value" has a different meaning: Token Meaning of "value" ---------------------------------------------------------- NUMBER The numeric value of the constant. STRING The offset into the literal pool. LABEL The value of the compiler generated label. SYMBOL Index into global symbol tables. All others Undefined. When token is a SYMBOL, the "value" passed is used to index into the global symbol tables (contained within the "compile" module) to determine information about the variable: s_name[value] - Name of symbol (up to SYMBOL_SIZE characters). s_type[value] - Type of symbol (bits defined in "compile.h"). s_index[value] - Variable index: Global: Index indicates symbol was the n'th one defined. Local: Index is stack offset from def_func. Argument: Index is stack offset from last argument pushed. When calculating the stack offset for ARGUMENTs, you must add the number of bytes placed on the stack when the function was called. This includes the local variables, the return address, and any other values that "def_func" might push. There are two popular ways of providing addressability to local variables: If the processor has many registers, you can reserve one as a "base" pointer, and point it at the top of the stack when the function is entered. This allows local variables to be referenced as negative offsets from that "base" register, and arguments to be referenced as positive offsets from it. This approach also allows the stack to be restored directly from this base register when the function terminates. See the section on assembly language interfacing. Another approach is to have the code generator "remember" exactly how many bytes have been pushed onto the stack since "def_func", and adjust the offsets it generates based on the stack contents. This has the advantage of not tying up a register. MICRO-C Page: 32 If you intend to use the MICRO-C Source Linker (SLINK), then you have to insure that whatever variable you use to reference the "literal pool" qualifies as a "compiler generated" label, allowing SLINK to adjust it when processing the source files. Compiler generated labels normally consist of a single character (usually '?'), followed by a decimal number. Since the compiler begins generating its labels with the value '1', you may safely use '0' as the literal pool variable (Ie: '?0'). It is the responsibility of the code generator to keep track of the validity of the upper 8 bits of the accumulator. Appropriate sign extension or clearing of high bits must be performed as necessary to convert signed and unsigned character values when 16 bit results when required. To improve the effiency of conditional statements, the code generator should keep track of the validity of the "zero" flag in the processor's condition code register, and generate appropriate "test" instructions only if necessary when a conditional jump is compiled. For processors not supporting operations with stack contents, the "ON_STACK" and "ION_STACK" tokens may implemented by first popping the top of the stack into a register. The "ISTACK_TOP" token is a special case, because the address on the top of the stack must not be lost. This token may be efficiently implemented, because "ISTACK_TOP" is only used for read/write operations to a stacked calculated address. For example: array1[i] += array2[i]; This statement calculates the address of "array1[i]" (in the index register). Since the "index" register is again used in calculating the address of "array2[i]", the first "index" will be placed on the stack. Once the contents of "array2[i]" are retrieved, it will be added using "ISTACK_TOP", and then re-stored using "ION_STACK". The "ISTACK_TOP" token may thus pop the address into a register, and set a flag indicating to the code generator that the next "ION_STACK" token is to go through that register rather than the top of the stack. Note that since an arithmetic operation may be performed between the two references, you must not use a register which is modified in code generated for arithmetic operations. Refer to the sample code generators distributed with the compiler. MICRO-C Page: 33 4.3 The "compile" module The "compile" module contains the main statement analyser, input scanner, expression parser and symbol table managment routines for the MICRO-C compiler. This module is common to all implementations, and should NOT require any changes. The source code for this module is contained in the "compile.c" file on your distribution diskette, and may be examined for insight into the internal operation of the compiler. This module must be compiled and linked with your I/O and code generation routines to generate a complete executable MICRO-C compiler. To test your code generator, the file "test.c" is provided which when compiled using the new compiler, performs a number of simple tests to verify your code generator. This is not a comprehensive analysis, as it makes no assumptions about the processor, however, it provides a good indication that your code generator is on the right track. A number of fixed parameters to the compiler (such as table sizes etc.) are contained in the header file "compile.h". The most common reason for changing these parameters is to reduce the memory requirements, in order to get MICRO-C to fit into very small systems. If any of the parameters in "compile.h" are to be changed, you must make the changes BEFORE compiling any of the modules (compile, io or codegen). The file "tokens.h" contains symbolic definitions for the tokens parsed by the compiler, the text of which is in the character array variable "tokens". If you make any changes to this token table, MAKE SURE that the contents of the "tokens" variable and the "tokens.h" file agree, otherwise, you will end up with a compiler for a very strange language. MICRO-C Page: 34 4.4 Porting without a compiler If you have the MICRO-C distribution files, but no running compiler, it is still possible to port MICRO-C, using the following steps: 1) You must write the code generator and I/O routines in another language. Using assembly language is preferable, because you can then follow the MICRO-C function calling conventions (See "Assembly Language Interface under "Advanced Topics"). This allows you to use the same routines with the compiler later. 2) The "genasm.c" program should then be re-written in the same language as above. This should not be difficult, since it is a fairly simple program. 3) Link "genasm" with your code generator and I/O routines, to create the "genasm" utility which reads intermediate files and produces assembly language output. 4) The "intermediate" file for the main "compile" module is provided in the file "compile.i". When this file is processed by "genasm", and the resultant file assembled, you will have the "compile" module which may be linked with the "io" and "code" modules to produce the final compiler. 4.5 Porting without a linker It is possible to port MICRO-C using a system which does not support a linker. To do this, you must concatinate all the source files "compile.c", "code.c" and "io.c" into one large file (in that order), and compile them all as one program. When this is done, the ".h" include files need only be included once, and external definitions of variables occuring in other source files should not be used. The source programs on the distribution disk all contain conditional compilation statements (#ifndef), which only perform the necessary #include and external definition statements when compiling as a single file. MICRO-C Page: 35 4.6 Optimization Techniques The MICRO-C compiler performs the following machine independant optimizations of the output file: 1) All constant expressions are evaluated at compile time, and expressed as a single constant value in the output code. 2) Operations which are not sensitive to order (eg: '+') may be reversed to take advantage of partial results already in the accumulator. 3) Redundant jumps as a result of "return" or "break" statements are suppressed. 4) The sense of jumps in conditional statements are reversed for logically negated expressions, code for '!' is only generated if the value returned by that operator is actually used. 5) Jumps between code generated within a single expression are flagged as "short". Although the MICRO-C compiler produces fairly reasonable code for the processor model it uses, that model is necessarily limited, in order that it might fit a large number of physical targets. There are several simple optimizations which may be performed to further enhance the code generated by the compiler in a specific implementation. 4.6.1 Register Usage MICRO-C assumes a single accumulator, and a single index register. Additional terms in complicated expressions are handled by placing temporary results on the processor stack, and re-using those registers. All data placed on the stack is accessed on a "last in - first out" basis. If the target processor has a full compliment of general purpose registers, an optimization may be performed by simply selecting another general purpose register as the accumulator or index register instead of placing the value on the stack. The code generator must keep track of the order in which registers are selected, and which register represents the "top" of the stack. If the number of values "pushed" exceeds the number of available registers, the "oldest" register should be placed on the stack, thereby allowing it to be re-used. MICRO-C Page: 36 4.6.2 Jump Optimization Although MICRO-C identifies jumps to instructions which span more than one expression as "long", often the addresses are close enough together that short jumps may actually be used. This optimization is particularily useful for processors such as the 8086, which does not support "long" conditional jumps, and therefore must simulate them with a short conditional jump of the opposite sense around a long unconditional jump. 4.6.3 Redundant Load Elimination Since MICRO-C evaluates and processes each statement individually, it does not carry partial results from one statement to another. Consider the following statements: a = x; b = a + 1; MICRO-C generates the code: LOAD x STORE a LOAD a ADD 1 STORE b An optimization may be performed by recognizing that the second "load" instruction is redundant, and can be eliminated. Note: A more efficent (but less readable) way of coding the above statements which would result in the latter code without optimization is: b = (a = x) + 1; MICRO-C Page: 37 4.6.4 Peephole Optimization Consider the statement: a = *++ptr; MICRO-C generates the code: LOAD ptr INCREMENT STORE ptr MOVE ACCUMULATOR TO INDEX LOAD [INDEX] STORE a For a processor supporting a rich set of direct memory addressing modes, the above sequence can be shortened to: INCREMENT_MEMORY ptr LOAD [ptr] STORE a One of the most successful techniques of optimizing the output code is also one of the simplest. Known as "peephole" optimization, the method consists of keeping a window of the last few instructions generated, and scanning the list for known patterns every time a new instruction is added to it. As long as the instructions in the list at least partially match one or more of the "predefined" patterns, additional instructions are collected until either a complete pattern match occurs, or all known patterns are eliminated. If no matches occur, the "oldest" instruction is written to the output file, and the next one becomes the first in the "window". Whenever a pattern is discovered, it is replaced by a new series of instructions which perform the same function, but in a more efficent manner. The new instruction sequences are replaced on the list, which may then be again scanned, allowing further possible reductions to be discovered. Handling of labels in the "window" and their corresponding placement in the output file must be carefully done, in order to preserve the "logical" context of the original code. MICRO-C Page: 38 5. THE MICRO-C PREPROCESSOR The MICRO-C Preprocessor is a source code filter, which provides greater capabilities than the preprocessor which is integral to the MICRO-C compiler. It has been implemented as a stand alone utility program which processes the source code before it is compiled. Due to the higher complexity of this preprocessor, it operates slightly slower than the the integral MICRO-C preprocessor. This is mainly due to the fact that it reads each line from the file and then copies it to a new line while performing the macro substitution. This is necessary since each macro may contain parameters which must be replaced "on the fly" when it is referenced. The integral MICRO-C preprocessor is very FAST, because it does not copy the input line. When it encounters a '#define'd symbol, it simply adjusts the input scanner pointer to point to the definition of that symbol. Keeping the extended preprocessor as a stand alone utility allows you to choose between greater MACRO capability and faster compilation. It also allows the system to continue to run on very small hardware platforms. The additional capabilities of the extended preprocessor are: - Parameterized MACROs. - Nested conditionals. - Ability to undefine MACRO symbols. - Library reference in include file names. MICRO-C Page: 39 5.1 The MCP command The format of the MICRO-C Preprocessor command line is: MCP [input_file] [output_file] [options] [input_file] is the name of the source file containing 'C' statements to read. If no filenames are given, MCP will read from standard input. [output_file] is the name of the file to write the processed source code to. If less than two filenames are specified, MCP will write to standard output. 5.1.1 Command Line Options MCP accepts the following command line [options]: -c - Instructs MCP to keep comments from the input file (except for those in '#' statements which are always removed). Normally, MCP will remove all comments. l=path - Defines the directory path which will be taken to reference "library" files when '<>' are used around an '#include' file name. Unless otherwise specified, the path defaults to: '/mc' -q - Instructs MCP to be quiet, and not display the startup message when it is executed. <name>=<text> - Pre-defines a non-parameterized macro of the specified <name> with the string value <text>. MICRO-C Page: 40 5.2 Preprocesor Commands The following commands are recognized by the MCP utility, only if they occur at the beginning of the source file line: 5.2.1 #define <name>(parameters) <replacement text> Defines a global macro name which will be replaced with the indicated <replacement text> wherever it occurs in the source file. Macro names may be any length, and may contain the characters 'a'-'z', 'A'-'Z', '0'-'9' and '_'. Names must not begin with the characters '0'-'9'. If the macro name is IMMEDIATELY followed by a list of up to 10 parameter names contained in brackets, those parameter names will be substituted with parameters passed to the macro when it is referenced. Parameter names follow the same rules as macro names. eg: #define min(a, b) (a < b ? a : b) If any spaces exist between the macro name and the opening '(', the macro will not be parameterized, and all following text (including '(' and ')') will be entered into the macro definition. 5.2.2 #undef <symbol> Undefines the named macro symbol. further references to this symbol will not be replaced. NOTE: With MCP, macro definitions operate on a STACK. IE: If you define a macro symbol, and then re-define it (without '#undef'ing it first), subsequently '#undef'ing it will cause it to revert to its previous definition. A second '#undef' would then cause it to be completely undefined. 5.2.3 #forget <symbol> Similar to '#undef', except that the symbol and ALL SUBSEQUENTLY DEFINED SYMBOLS will be undefined. Useful for releasing any local symbols (used only within a single include file). For example: #define GLOBAL "xxx" /* first global symbol */ ... /* more globals */ #define LOCAL "xxx" /* first local symbol */ ... /* more locals */ /* body of include file goes here */ #forget LOCAL /* release locals */ MICRO-C Page: 41 5.2.4 #ifdef <symbol> Causes the following lines (up to '#else' of '#endif') to be processed and included in the source file only if the named symbol is defined as a macro. 5.2.5 #ifndef <symbol> Causes the following lines (up to '#else' of '#endif') to be processed and included in the source file only if the named symbol is NOT defined as a macro. NOTE: '#ifdef/#ifndef#else/#endif' may be nested. 5.2.6 #else Toggles the state of the "if_flag", controlling conditional processing. Only has effect in the highest level of suspended processing. IE: Nested conditionals will work properly. If the previous '#ifdef/#ifndef' failed, processing will begin again following the '#else'. If the previous '#ifdef/#ifndef' passed, processing will be suspended until the '#endif' is encountered. NOTE: Since '#else' acts as a toggle, it may be used outside of any '#ifdef/#ifndef' to unconditionally suspend processing up to '#endif'. 5.2.7 #endif Resets the "if_flag" controlling conditionals, causing processing to resume. Only has effect in the highest level of suspended processing. IE: Nested conditionals will work properly. MICRO-C Page: 42 5.2.8 #include <filename> Causes MCP to open the named file and include its contents as part of the input source. If the filename is contained within '"' characters, it will be opened exactly as specified, and (unless it contains a directory path) will reference a file in the current directory. If the filename is contained within the characters '<' and '>', it will be prefixed with the library path (See 'l=' option), and will therefore reference a file in that library directory. The default library directory is assumed to be '/mc'. For example: #include "header.h" /* from current directory */ #include <stdio.h> /* from library directory */ 5.2.9 #asm / #endasm The '#asm' and '#endasm' statements are not actually recognized by MCP. They are passed through unchanged, allowing them to be recognized and acted upon by the integral MICRO-C preprocessor. MICRO-C Page: 43 5.3 Error messages When MCP detects an error during processing of an include file, it displays an error message, which is preceeded by the line numbers of the files in which the error occurs. If more than 10 errors are encountered, MCP will terminate. The following error messages are reported by MCP: 5.3.1 Cannot open include file A '#include' statement on the indicated line specified a file which could not be opened for reading. 5.3.2 Invalid include file name A '#include' statement on the indicated line specified a file name which was not contained within '"' or '<>' characters. 5.3.3 Invalid macro name A '#define' statement on the indicated line contains a macro name which does not follow the name rules. 5.3.4 Invalid macro parameter A '#define' statement on the indicated line contains a macro parameter name which does not follow the name rules. A reference to a macro does not have a proper ')' character to terminate the parameter list. 5.3.5 Too many errors More than 10 errors has been encountered and MCP is terminating. 5.3.6 Too many macro definitions MCP has encountered more '#define' statements than it can handle. 5.3.7 Too many macro parameters A '#define' statement on the indicated line specifies more parameters to the macro than MCP can handle. 5.3.8 Too many include files MCP has encountered more nested '#include' statements than it can handle. MICRO-C Page: 44 5.3.9 Undefined macro A '#undef' or '#forget' statement on the indicated line references a macro name which has not been defined. 5.3.10 Unterminated comment The END OF FILE has been encountered while processing a comment. 5.3.11 Unterminated string A quoted string on the indicated line has no end. MICRO-C Page: 45 6. THE MICRO-C OPTIMIZER The MICRO-C optimizer is an output code filter which examines the assembly code produced by the compiler, recognizing known patterns of inefficent code (using the "peephole" technique), and replaces them with more optimal code which performs the same function. It is entirely table driven, allowing it to be modified for virtually any processor. Due its many table lookup operations, the optimizer may perform quite slowly when processing a large file. For this reason, most people prefer not to optimize during the debugging of a program, and utilize the optimizer only when creating the final copy. 6.1 The MCO command The format of the MICRO-C Optimizer command line is: MCO [input_file] [output_file] [options] [input_file] is the name of the source file containing assembly statements to read. If no filenames are given, MCO will read from standard input. [output_file] is the name of the file to which the optimized assembly code is to be written. If less than two filenames are specified, MCO will write to standard output. 6.1.1 Command Line Options MCO accepts the following command line [options]: -d - Instructs MCO to produce a 'debug' display on standard output showing the source code which it is removing and replacing in the input file. NOTE: If you do not specify an explict output file, you will get the debug statements intermixed with the optimized code on standard output. -q - Instructs MCO to be quiet, and not display the startup message when it is executed. MICRO-C Page: 46 6.2 Porting to a new processor The MICRO-C Optimizer is completely table driven, and should be fairly easy to port to a new processor. The peephole optimization table is called 'peep_table', and consists of two sequential character string entries for each optimization. The first is the "take" entry, and represents an instruction sequence which (if found) is to be removed from the output file. The second is the "give" entry, and defines a sequence of instructions to be placed in the output file at that point. NOTE that due to the way the optimizer removes and replaces instruction in the circular "peephole" buffer, the instructions in the "give" entry ARE CODED IN REVERSE ORDER. Characters in the "take" entry with the high bit set (eg: '\200','\201') are special characters which represent any variable string which may occur in the instruction sequence, and will be replaced with the same string wherever that character occurs in the "give" entry. If the same special character (eg: '\200') occurs more than once in the "take" entry, the corresponding strings must be exactly the same or else the entire sequence will not be matched. The processor will stop scanning a variable string when it encounters the character which immediately follows the special character in the "take" entry, or at the end of the input line. The manifest SYMBOLS defines how many different special characters are allowed in a peephole entry. You must not use any special characters which have a value greater than ('\200' + SYMBOLS - 1). MICRO-C Page: 47 7. THE COMMAND CO-ORDINATOR 'CC' is a program which co-ordinates the other commands (MCP, MCC, MCO, ASM and LINK), to provide a simple "one step" compilation command. 7.1 The CC command The format of the Command Co-ordinator command line is: CC <name> [options] 7.1.1 Command line options -a - produce ASSEMBLER (.ASM) output file -l - produce LINKABLE (.OBJ) output file -o - OPTIMIZE the output file (using MCO) -p - use the extended PRE-PROCESSOR (MCP) -q - QUIET mode (suppress informational messages) -s - produce SMALL-MODEL (.EXE) output file m=mcdir - specify MICRO-C home directory t=mctmp - specify prefix for TEMPORARY files When executing the sub-commands, CC will search the MICRO-C home directory, as well as any directories specified in the 'PATH' environment variable. Libraries are accessed from the MICRO-C home directory only. The environment variable 'MCDIR' is examined to determine the path to the MICRO-C home directory. If MCDIR is not defined, CC will assume the string '\MC'. You may override this directory by using the 'm=' option on the command line. Intermediate results from each command are stored in "temporary" files, which are fed as input to the next command. Temporary files will be deleted once they are no longer needed, except in the case where a command fails. When this happens, any temporary file which was being used as input to that command will not be deleted, allowing you to examine it for the cause of the error. The environment variable 'MCTMP' is examined to determine a prefix to prepend to temporary file names. If MCTMP is not defined, CC assumes the default prefix of '$'. You may override this prefix by using the 't=' option on the command line. Here are example 'SET' commands suitable for inclusion in the AUTOEXEC.BAT file, of an IBM/PC based MICRO-C system which has the home directory in 'C:\MC', and a RAMDISK as drive 'D': SET MCDIR=C:\MC SET MCTMP=D:\$ MICRO-C Page: 48 The '-p' option causes the extended pre-processor (MCP) to be used. This provides greater pre-processor capability, at the expense of longer compile time. NOTE: If any compiler errors occur when using this option, the line numbers contained in the error messages will refer to the temporary file containing the output from the pre-processor ($<name>.CP). You must examine this file in order to determine the actual cause of the error. The '-o' option causes the optimizer (MCO) to be used, which results in more efficent code, at the expense of longer compile time. The '-a' option causes CC to bypass the assembler and linker, and produce an assembly source file (<name>.ASM) as the output file. The '-l' option causes CC to bypass the link stage, and produce a linkable object module (<name>.OBJ) as the output file. The '-s' option causes CC to link the program using the SMALL memory model, and produce an executable image (<name>.EXE) as the output file. This option applies only to those processors which have a segmented architecture and multiple memory models such as the 8086. If none of '-a', '-l' or '-s' is specified, CC will link the program using the TINY memory model, and produce a command image (<name>.COM) as the output file. 7.2 Using multiple object modules The 'LC' command file takes one or more object modules produced by 'CC' with the '-l' option, and links them with the libraries to produce an executable module. This module will be given the name of the first file specified in the argument list. When compiling large programs which have more than one source file, you must first compile all modules using 'CC' with the '-l' option, and the use 'LC' to link the resultant object files into the final executable program. The '-s' option may be used as the FIRST argument, to cause LC to link in the SMALL model (8086 only). eg: CC FIRST -l CC SECOND -l LC FIRST SECOND <-- TINY Model LC -s FIRST SECOND <-- SMALL Model The exact syntax and options available for 'CC' and 'LC' may differ in different implementations of the compiler. See the 'READ.ME' file on your distribution disk for details. MICRO-C Page: 49 8. THE MAKE UTILITY The MAKE utility provides a method of automating the building of larger programs consisting of more that one object module. The main benefit of MAKE is that it keeps track of the files that each module is dependant on, and will rebuild a module if any of those files have been modified since the module was last built. This frees the programmer from the task of remembering which files have been changed, and the commands needed to rebuild the dependant modules. 8.1 MAKEfiles To use MAKE, you must first create a MAKEFILE, which is a text file containing entries for each module in the program. Each entry consists of a DEPENDANCY list, and a series of COMMANDS. 8.1.1 MAKEfile Entries A dependency list in MAKE is a line which contains the name of the module, followed by a ':', followed by the names of any files on which it depends. The module name MUST begin in column 1. When MAKE is invoked, it will process each dependancy list, and will execute any following commands (up to another dependancy list) if (1) the module does not exist, or (2) if any of the files to the right of the ':' have a timestamp which is later than that of the module. For example: main.obj : main.c main.h \\mc\\stdio.h \\mc\\mcc main.c main.asm masm/ml main; -del main.asm In the above example, the 'main.obj'would be rebuilt (by compiling and assembling 'main.c') if either it did not already exist, or any of 'main.c', 'main.h' or '\mc\stdio.h' was found to have a later timestamp. The '-' preceeding the 'del' command prevents it from being displayed. Unless the '-q' option is enabled, MAKE will display any commands not preceeded by '-' as they are executed. NOTE: To enter a single '\' in the MAKEFILE, you must use '\\', this is because like 'C', MAKE uses '\' to "protect" special characters which otherwise are used for special functions (such as '\', '$' and '#'). The first '\' "protects" the second one, allowing it to pass through as source text. MICRO-C Page: 50 8.1.2 Macro Substitutions Sometimes in a MAKEFILE, you have a single file or directory path that you use over and over again. If it is a long directory path, this may involve a lot of typing, and it becomes inconvenient to change that name (if you want to use a different directory etc.) because it is repeated many times. MAKE includes a MACRO facility, which allows you to define variable names which will be replaced with a text string when used in subsequent MAKEfile lines. Names are defined by placing them in the MAKEfile, followed by '=', and the text string. Macro names being defined MUST begin in column one, and may consist of the characters ('a'-'z', 'A'-'Z', '0'-'9', and '_'). Whenever MAKE encounters a '$' in the file, it takes the name immediately following, and performs the macro replacement: mcdir = \\mc main.obj : main.c main.h $mcdir\\stdio.h $mcdir\\mcc main.c main.asm masm/ml main; del main.asm When a macro name is immediately followed by alphanumeric text, use a single '\' to separate it from the text. This "protects" the first character of the text from being interpreted as part of the macro name: mcdir = \\mc\\ main.obj : main.c main.h $mcdir\stdio.h $mcdir\mcc main.c main.asm masm/ml main; del main.asm There are several predefined macro symbols which are available: $* = The full name of the dependant module (name.type). $@ = The name only of the dependany module. $. = The full name of each file in the dependancy list, separated from each other by a single space. $, = The full name of each file in the dependancy list, separated from each other by a single comma. $: = The name only of each file in the dependancy list, separated from each other by a single space. $; = The name only of each file in the dependancy list, separated from each other by a single comma. MICRO-C Page: 51 File names in the dependancy list which are preceeded by '-' will not be included in the '$. $, $: $;' macro expansions: mcdir = \\mc main.obj : main.c -main.h -$mcdir\\stdio.h $mcdir\\mcc $. $@.ASM masm/ml $@; del $@.ASM 8.1.3 MAKEfile Comments Whenever MAKE encounters the '#' character in the MAKEFILE, it treats the remainder of the line as a comment, and does not process it: # Define Directories mcdir = \\mc # Build the MAIN module main.obj : main.c -main.h -$mcdir\\stdio.h # Dependants $mcdir\\mcc $. $@.ASM # Compile masm/ml $@; # Assemble del $@.ASM # Delete tmp 8.1.4 Ordering the MAKEfile MAKE processes the MAKEfile is sequential fashion, with the entries near the top being processed before the entries near the bottom. To insure that each module is built properly, any files appearing in the dependancy list for a module which are themselves dependant on other files, should have MAKEfile entries which occur BEFORE the entries for the modules which are dependant on them: # Define Directories mcdir = \\mc # Build the MAIN module main.obj : main.c -main.h -$mcdir\\stdio.h $mcdir\\mcc $. $@.ASM masm/ml $@; del $@.ASM # Build the SUB module sub.obj : sub.c -sub.h $mcdir\\mcc $. $@.ASM masm/ml $@; del $@.ASM # Bind the executable file # NOTE: If either of the above modules is rebuilt, # this entry will be guarenteed to execute. main.exe : main.obj sub.obj LINK $:; MICRO-C Page: 52 8.2 Directives Like 'C', MAKE recognizes several "directives" in the MAKEfile. These directives are only recognized if they occur at the beginning of the input line: 8.2.1 @include <filename> This command causes the indicated file to be opened and read in as the source text. When the end of the new file is encountered, processing will continue with the line following "@include" in the original MAKEfile. 8.2.2 @ifdef <name> Processes the following lines (up to @else of @endif) only if the given MACRO name is defined. NOTE: <name> should not be preceeded by '$', otherwise its CONTENTS will be tested. 8.2.3 @ifndef <name> Processes the following lines (up to @else of @endif) only if the given MACRO name is NOT defined. 8.2.4 @ifeq <word1> <word2> Processes the following lines (up to @else of @endif) only if the following two words match exactly. This is useful for testing the value of a defined MACRO symbol. 8.2.5 @ifne <word1> <word2> Processes the following lines (up to @else or @endif) only if the following two words do not match. 8.2.6 @else Processes the following lines (up to @endif) only if the preceeding @ifdef, @ifndef, @ifeq or @ifne was false. 8.2.7 @endif Terminates @ifdef, @ifndef, @ifeq and @ifne. 8.2.8 @type <text> Displays the following text. 8.2.9 @abort [text] Terminates MAKE with an 'Aborted!' message. Any text on the remainder of the line will be appended to the message. MICRO-C Page: 53 8.3 The MAKE command The format of the MAKE command line is: MAKE [makefile] [options] [makefile] is the name of the MAKEfile to process. If no name is given, MAKE assumes the default name 'MAKEFILE'. 8.3.1 Command Line Options MAKE accepts the following command line [options]: -d - Instructs MAKE to operate in "debug" mode, and display the commands which it would execute, without actually executing them. This provides a method of quickly testing the MAKEFILE. -q - Instructs MAKE to be quiet, and not display the informational messages and commands executed as it progresses. <name>=<text> - Pre-defines a macro of the specified <name> with the string value <text>. This OVERRIDES any definition within the MAKEfile, which may be used to establish a "default" value. MICRO-C Page: 54 8.4 The TOUCH command TOUCH is a small utility program which sets the timestamp of one or more files to the current or specified time/date. It is useful as a method of forcing MAKE to recognize a file as "changed", even when it has not. For example, if you had decided to "undo" several recent changes by restoring a backup of "main.c", the restored file will probably have a timestamp which is older than the last module which was built. In this case, MAKE would be unaware that the file has changed, and would therefore not rebuild the module. The TOUCH command could then be used to "update" the timestamp of 'main.c' to the current time, causing MAKE to recognize it as a changed file. TOUCH main.c You could also use TOUCH to force rebuilding of several files: TOUCH main.c sub1.c sub2.c Or even ALL '.C' files: TOUCH *.c TOUCH can also be used to set the timestamp of a file to an arbritrary value, this may be useful to PREVENT a change from causing an update: TOUCH main.c t=0:00 d=31/10/80 NOTE: Use of the 't=' or 'd=' parameters to TOUCH allows the possibility that a changed file will go unnoticed. CAUTION is advised. MICRO-C Page: 55 9. THE SOURCE LINKER Many small development environments have assemblers which do not directly support an object linker. This causes a problem with 'C' development, because the library functions must be included in the source code, with several drawbacks: 1) There is no way to tell which library functions to include, therefore, you must to it manually. 2) 'C' library functions must be re-compiled every time, in order to avoid conflict between compiler generated labels. 3) Assembly language library functions must be modified to include the "#asm" and "#endasm" directives. The MICRO-C Source Linker (SLINK) helps overcome these problems, by automatically joining previously compiled (assembly language) source code from the library to your programs compiler output. Only those files containing functions which you reference are joined (Taking into consideration of course any functions called by the included library functions etc...). As the files are joined, compiler generated labels are automatically adjusted to be unique within each file. 9.1 The SLINK Command The format of the SLINK command line is: SLINK [input_file] [output_file] [options] [input_file] is the name of the source file containing the compiler output from your program. If no filenames is given, SLINK will read from standard input. [output_file] is the name of the file to write the linked source code to. If less that two filenames are given, SLINK will write to standard output. 9.1.1 Command line options SLINK accepts the following command line [options]: g=char - Informs SLINK of the lead-in character for compiler generated symbols. This defaults to '?' unless otherwise specified. -l - Instructs SLINK to list each library file being included in your program. l=path - Identifies the directory path which will be taken to reference "library" files. If this path is not specified, it defaults to: '/mc/slib' -q - Instructs SLINK to be quiet, and not display the startup message when it is executed. MICRO-C Page: 56 9.2 The External Index File SLINK uses a special file from the library to determine which sysmbols are in which files. This files is called the EXTERNAL INDEX FILE, and is found in the library directory (see 'l=' option), under the name "EXTINDEX.LIB". This file contains entries which cross-reference external symbols to files. Each entry is as follows: 1) Any lines beginning with '+' contain the names of files which are to be processed and included at the beginning of the program (Before your source file). This the best way to include the startup code and any runtime library routines which are required at all times. The files are included in the order in which they appear in the index file. eg: +6809rl.asm 2) Any lines beginning with '-' contain the names of files which are to be included if any of the following symbols (Up to another '+' or '-') are referenced. eg: -printf.asm format.asm fput.asm NOTE: In most cases, the library functions will contain indications of any external references that they do, in which case SLINK will automatically include those files even of the names are not mentioned on the '-' line. In the example above, the following would suffice: -printf.asm 3) The names of each symbol which may be referenced externally must follow the '+' or '-' entry. Symbols must occur one per line, with no leading or trailing spaces. eg: printf fprintf sprintf 4) A line beginning with '$' is used to define the pseudo- opcode used by SLINK to reserve uninitialized data at the end of the output file. One one line beginning with '$' should be entered into the EXTINDEX.LIB file. The remainder of this line, including all spaces etc. is entered between each symbol name, and the decimal size (in bytes) which is written to the output file. eg: '$ RMB ' <- Quotes are for clarity MICRO-C Page: 57 A complete example: +6809rl.asm -printf.asm printf fprintf sprintf -scanf.asm scanf fscanf sscanf $ RMB 9.3 Multiple source files SLINK processes only one source file, and resolves external references only to the library files. This is because the public symbol information is available in the EXTINDEX.LIB files, which contains no entries for the user supplied programs. If you wish to use source code linking for a program which contains multiple source files, use "#include" statements at the end if your main program to include all of the other parts into a single source file. 9.4 Source file information 9.4.1 Special Comments SLINK identifies external symbol references by special comments in the input source file. These comments must begin in column one, and are of the form: *EXT*<symbol> where <symbol> is the name of the symbol being referenced. These comments are placed into the source file by the "def_extern" routine in the MICRO-C code generator. MICRO-C Page: 58 SLINK also identifies uninitialized data area by special comments placed in the input source file. The comments must begin in column one, and are of the form: *DAT*<symbol> <size> where <symbol> is the name of the symbol used to reference the data area, and <size> is the number of bytes to be reserved. SLINK will output statements to allocate the data area at the very end of the assembly language output file. This prevents the uninitialized data from occupying space within the bounds of executable code generated, and thus allows it to be excluded from the image when it is saved to disk. These comments are placed into the source file by the "def_global" routine in the MICRO-C code generator. The reserved data area are allocated at the end of the output file, in the REVERSE order of which they are encountered in the input files. This insures that the FIRST "*DAT*" comment found the LAST symbol name output. This allows you to place a "*DAT*" comment at the beginning of the startup file, and use it to allocate heap space at the end of all other data. If you are writing assembly language programs for the library, be sure include "*EXT*<symbol>" comments for any symbols which you externally reference, and "*DAT*<symbol> <size>" comments for any uninitialized data area you may wish to allocate. If you wish to place an assembly language comment on the same line, make sure it is separated from the remainder of the special comment line by at least one space or tab character. Note that since SLINK removes these "special" comments from the output file, they do not have to be in a form acceptable to the assembler. Ie: if your assembler uses ';' for comments, you don't not have to change the code generator and SLINK, since the assembler will not see the special comments it generates. 9.4.2 Compiler generated labels As it processes each source file, SLINK scans each line for symbols which consist of the '?' character (See 'g=' option), followed by a number. If it finds such as symbol, it inserts a two character sequence ranging from 'AA' to 'ZZ' between the '?', and the number. This sequence will be incremented for each source file processed, and thus insures that the compiler generated symbols will be unique for each file. If you are writing assembly language programs for the library, you must be careful to avoid using identical local symbols in any of the library files, one way to do this is to use symbols which meet the above criteria. MICRO-C Page: 59 9.5 The SINDEX utility SINDEX is a utility which assists in the creation of the EXTINDEX.LIB file used by SLINK. When you run SINDEX, it examines all of the '.ASM' files in the current directory, and writes a EXTINDEX.LIB file which contains a '-' type entry for each file, and external symbol entries for any labels which it finds conforming to the 'C' naming conventions (Starts with 'a-z', 'A-Z' or '_', and contains only 'a-z', 'A-Z', '0-9' or '_'). Once you have run SINDEX, you must manually edit the EXTINDEX.LIB file, and remove any file or symbol entries which you do not wish to have available as external references, as well as change any necessary entries to the '+' type. NOTE: There is no information recorded in the assembly source file which indicates that a symbol was declared as "static" in 'C'. For this reason, you must manually remove any symbols which you do not want to be accessable as external references, EVEN IF THEY WERE ORIGINALLY DECLARED AS "static" IN 'C'. You may instruct SINDEX to search for a file pattern other than '*.ASM' by passing it as a command line parameter. eg: SINDEX *.A86 MICRO-C Page: 60 10. LIBRARY FUNCTIONS The MICRO-C distribution disk includes the 'C' and 'ASM' source code for a number of useful "library" functions. These routines may be also be used as "example" programs, providing insight into MICRO-C programming techniques. All functions except for the lowest level I/O routines are coded in 'C', and should compile on any MICRO-C system. Note that some low level functions in the library are written in 'C' using still lower level routines. Although this makes the library highly portable and reduces the number of routines you have to re-write for a specific system, the resultant function will be less efficent than one which directly uses the operating system services. If you are implementing MICRO-C an a small system and intend to use it for serious programming, I strongly recommend that you re-code all of the low level library functions in assembly language. Note that since library routines are often used, in applications where code size and execution speed are of primary importance, it may be desirable to recode some or all of the other library routines in assembly language as well. For those who intend to make only casual use of MICRO-C, or who wish to experiment with it simply for the learning experience, the 'C' versions of the low level library functions should be more than sufficient. 10.1 Standard Library Functions These routines are currently available in the MICRO-C library as "standard" functions which should be available in all implementations. The exact syntax and capabilities of the system or processor dependant functions may vary in different implementations, see your implementation notes (READ.ME) for details. Different possible forms of such functions are shown using (1), (2), ... ABORT ABORT PROTOTYPE: abort(char *message) ARGUMENTS: message - Pointer to message to display RETURN VALUE: N/A - Function never returns DESCRIPTION: This function writes the string passed as an argument to standard error, and then terminates the program with a return code of '-1' (Indicating general failure). This provides a simple method of terminating a program on an error condition with a message explaining why. EXAMPLES: abort("Invalid operand\n"); ABS ABS PROTOTYPE: int abs(int number) ARGUMENTS: number - Any integer value RETURN VALUE: The absolute value of "number" DESCRIPTION: The "abs" function returns the absolute value of the argument. If "number" is a positive value, it is returned unchanged. If negative, the negate of that value is returned (giving a positive result). EXAMPLES: difference = abs(value1 - value2); ATOI ATOI PROTOTYPE: int atoi(char *string) ARGUMENTS: string - Pointer to a string containing a decimal number RETURN VALUE: 16 bit integer value DESCRIPTION: The "atoi" function converts an ASCII string containing a signed decimal number (-32768 to 32767) to a 16 bit value which is returned. An unsigned number of the range (0 to 65535) may also be used, and the result if assigned to an "unsigned" variable will be correct. EXAMPLES: value = atoi("1234"); value = atoi("-1"); CD CD PROTOTYPE: int cd(char *pathname) ARGUMENTS: pathname- Name of directory to make current RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: This function sets the "current" directory, causing all subsequent file references which do not explicitly indicate a directory path to access the path specified by "pathname". EXAMPLES: cd("/mc/c_source"); /* UNIX */ cd("\\mc\\l_source"); /* MS-DOS */ CONCAT CONCAT PROTOTYPE: register concat(char *dest, char *source, ...) ARGUMENTS: dest - Pointer to destination string source - Pointer to source string ... - Additional sources may be given RETURN VALUE: None DESCRIPTION: The "concat" function concatinates the given source strings into one destination string. The destination string must be large enough to hold all of the source strings plus the string terminator (zero) byte. No value is returned. NOTE: This function uses a variable number of arguments, and must be declared as "register" (See "stdio.h"). EXAMPLES: concat(filename,"/tmp/", input_name); CREATE CREATE PROTOTYPE: int create(char *pathname, int attrs) ARGUMENTS: pathname- Name of file to create attrs - Attributes for new file RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: The "create" function creates a new file with the specified system attributes. The meaning of the individual bits in the "attrs" value is system dependant, and is defined in the "file.h" header file. EXAMPLES: create("temp", HIDDEN); DELETE DELETE PROTOTYPE: int delete(char *pathname) ARGUMENTS: pathname- Name of file to delete RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: The "delete" function removes an existing file from the disk. Any disk space occupied by the file is released. EXAMPLES: delete("temp"); EXIT EXIT PROTOTYPE: exit(int rc); ARGUMENTS: rc - Termination return code RETURN VALUE: N/A - Function never returns DESCRIPTION: This function terminates the execution of the program and passes a specific return code back to the operating system. A return code value of zero is used to indicate successful program completion. Non-zero return code values may be used to indicate a particular type of failure. A value of '-1' is often used to indicate a non-specific failure. Note that the "rc" value is very system specific, in particular, some systems support only 8 bit return codes, so values which are greater than 255 should be avoided. EXAMPLES: exit(0); /* success */ exit(-1); /* failure */ FCLOSE FCLOSE PROTOTYPE: fclose(FILE *fp); ARGUMENTS: fp - File pointer to an open file RETURN VALUE: None DESCRIPTION: This function closes a file which was previously opened using "fopen". The I/O buffer space used by the file is released. In the case of a file open for write ('w'), the last disk buffer is flushed and written to disk. EXAMPLES: fclose(fp); FGET FGET PROTOTYPE: int fget(char *buffer, int size, FILE *fp) ARGUMENTS: buffer - Pointer to buffer to receive data size - Number of bytes to read fp - File pointer to an input file RETURN VALUE: Number of bytes read from file DESCRIPTION: This function reads a block of data from a file and places it in memory at the address of "buffer". Data is read in "raw" form, with no interpretation of "newline" characters etc. If the number of bytes returned is less than the number of bytes requested, either the end of the file was encountered or an error condition occured (in which case the value will be zero). EXAMPLES: fget(block, 512, input_fp); FGETS FGETS PROTOTYPE: char *fgets(char *buffer, int size, FILE *fp) ARGUMENTS: buffer - Pointer to string to receive line size - Maximum size of line to read fp - File pointer to an input file RETURN VALUE: Pointer to "buffer", or 0 if end of file DESCRIPTION: The "fgets" function reads characters from the specified input file, and places them in the character buffer until one of three things happens: 1) A NEWLINE character is encountered. 2) The END of the file is encountered. 3) The limit of "size" character is read. The string is terminated with the standard NULL (00) character. The trailing NEWLINE '\n' character is NOT included in the output buffer. EXAMPLES: fgets(input_line, 80, input_file); FIND_FIRST FIND_FIRST PROTOTYPE: int find_first(char *pattern, int mattrs, char name[], int &sizeh, int &sizel, int &attrs, int &time, int &date) ARGUMENTS: pattern - File name pattern to match mattrs - File attributes to match name - Address of string to receive file name &sizeh - Address of int to receive high word of size &sizel - Address of int to receive low word of size &attrs - Address of int to receive attributes &time - Address of int to receive time stamp &date - Address of int to receive date stamp RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: This function locates the first file on the disk which matches the given pattern. The "mattrs" field specifies any special attributes the files must have in order to be matched, use 0 for normal directory searches. Subsequent files may be located using the "find_next" function. The above function prototype describes the MS-DOS implementation of the function. With other operating systems, the function may have slightly different parameters, due to differing information available. See your implementation notes. EXAMPLES: if(find_first(pattern, 0, name, &sh, &sl, &a, &t, &d)) abort("No matching files found\n"); FIND_NEXT FIND_NEXT PROTOTYPE: int find_next(char name[], int &sizeh, int &sizel, int &attrs, int &time, int &date) ARGUMENTS: name - Address of string to receive file name &sizeh - Address of int to receive high word of size &sizel - Address of int to receive low word of size &attrs - Address of int to receive attributes &time - Address of int to receive time stamp &date - Address of int to receive date stamp RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: The function must be preceeded by a call to "find_first", and will locate the next file on the disk which matches the pattern and attributes given to that function call. The above function prototype describes the MS-DOS implementation of the function. With other operating systems, the function may have slightly different parameters, due to differing information available. See your implementation notes. EXAMPLES: do printf("%s\n", name); while(!find_next(name, &sh, &sl, &a, &t, &d)); FOPEN FOPEN PROTOTYPE: FILE *fopen(char *filename, char *options) ARGUMENTS: filename- Name of the file to open options - String containing open options, valid modes are: "r" - Open file for read "w" - Open file for write "rw" - Open for read/write update "wa" - Open for write & append RETURN VALUE: File pointer to the file buffer for the open file Zero (0) if file could not be opened DESCRIPTION: This function opens a file for input ('r') or output ('w'), allowing subsequent I/O operations to read or write the file. EXAMPLES: fp = fopen("input_file", "r"); FPRINTF FPRINTF PROTOTYPE: register fprintf(FILE *fp, char *format, arg, ...) ARGUMENTS: fp - File pointer to an output file format - Pointer to format string arg - Argument as determined by format string ... - Additional arguments may be required RETURN VALUE: None DESCRIPTION: This routine performs a formatted print to a file specified by "fp". The "format" string is written to the file with the arguments substituted for special "conversion characters". These "conversion characters" are identified by a preceeding '%', and may be one of the following: b - Binary number c - Character d - Decimal (signed) number o - Octal number s - String u - Unsigned decimal number x - Hexidecimal number % - A single percent sign (No argument used) A numeric "field width" specifier may be placed in between the '%' and the conversion character, in which case the value will be output in a field of that width. If the "field width" is a negative number, the output will be left justified in the field, otherwise it is right justified. If the field width contains a leading '0', then the output field will be padded with zero's, otherwise spaces are used. If no "field width" is given, the output is free format, using only as much space as required. NOTE: This function uses a variable number of arguments, and must be declared as "register" (See "stdio.h"). EXAMPLES: fprintf(stderr,"Filename='%s'\n", filename); fprintf(stdout,"Address=%04x\n", address); fprintf(outfile,"Amount: $%3u.%02u\n", amount / 100, amount % 100); FPUT FPUT PROTOTYPE: int fput(char *block, int size, FILE *fp) ARGUMENTS: block - Pointer to a block of data to write size - Number of bytes to write fp - File pointer to an output file RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: This function writes a block of data to the indicated file from memory at the specified address. Data is written in "raw" form, with no translations of "newline" characters etc. If the value returned is less than the value of the "size" parameter, some error condition has occured (Such as disk full). EXAMPLES: if(fput(buffer, 100, fp) < 100) abort("File write error\n"); FPUTS FPUTS PROTOTYPE: fputs(char *string, FILE *fp) ARGUMENTS: string - Pointer to a character string fp - FIle pointer to output file RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: The "fputs" function writes the specified string to the indicated output file. The zero terminating the string is NOT written. EXAMPLES: fputs("Text message", output_file); FREE FREE PROTOTYPE: free(char *ptr) ARGUMENTS: ptr - Pointer to a previously allocated memory block RETURN VALUE: None DESCRIPTION: The "free" function releases (de-allocates) a block of memory that was obtained via a call to "malloc", and returns it to the heap. This makes it available for use by other memory allocations. EXAMPLES: if(!(ptr = malloc(BUFSIZ))) /* Allocate a temporary buffer */ abort("Not enough memory"); do { /* Copy the file over */ size = fget(ptr, BUFSIZ, in_fp); fput(ptr, size, out_fp); } while(size == BUFSIZ); free(ptr); /* Release temporary buffer */ FSCANF FSCANF PROTOTYPE: register int fscanf(FILE *fp, char *format, &arg, ...) ARGUMENTS: fp - File pointer to an input file format - Pointer to format string arg - Argument as determined by format string ... - Additional arguments may be required RETURN VALUE: The number of successful matches EOF (-1) if end of file or an error condition occurs DESCRIPTION: This routine reads a line from the specified file and scans it for specific values which are then assigned to the passed argument addresses. The types of values scanned are determined by special "conversion characters" within the "format" string. These "conversion characters" are identified by a preceeding '%', and may be one of the following: b - Binary number c - Character d - Decimal (signed) number o - Octal number s - String u - Unsigned decimal number x - Hexidecimal number % - A single percent sign (No argument used) Before scanning for any value, any leading "space" or "tab" characters in the input line are automatically flushed. Scanning of a particular value type will terminate when either the end of the line or a non-applicible character is encountered. Scanning of strings (%s) stops with a "space" or "tab" character, and the stored string will be zero terminated. A numeric "field width" specifier may be placed in between the '%' and the conversion character, in which case scanning of the value will also terminate if that many input characters have been processed. Scanning for characters (%c) assumes a "field width" of 1 character (%1c) unless it is otherwise specified. Any other (non-conversion) characters in the format string will cause the next character in the input string which is not a "space" or "tab" to be skipped if it matches that character. Any variable values from the input line which are not required must be cleared by scanning them into a "dummy" variable. The most common mistake when using "fscanf" is forgetting to use the '&' operator with a simple variable argument. This causes "fscanf" to store the value INDIRECTLY at the address contained in that variable (Similar to using '*' with a pointer) instead of storing the value into the actual variable itself. Arguments which are array names do not require the '&' operator, since the address of the array is already generated by reference to its name. Unlike "fscanf" in most other compiler libraries, the MICRO-C function always reads and scans a single line from the input file. NOTE: This function uses a variable number of arguments, and must be declared as "register". EXAMPLES: if(fscanf(infile,"%s %s %u", first_name, last_name, &age) != 3) abort("Error in user record\n"); FSEEK FSEEK PROTOTYPE: (1) int fseek(FILE *fp, int h_offset, unsigned l_offset, int mode) (2) int fseek(FILE *fp, int offset, mode) ARGUMENTS: fp - File pointer to an open file h_offset- Highest 16 bits of offset value l_offset- Lowest 16 bits of offset value offset - 16 bit offset value mode - Type of seek 0 = Absolute from start of file 1 = Signed offset from current position 2 = Signed offset from end of file RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: This function positions the operating system internal pointer into a file so that any read or write will take place at the specified position in the file. Most operating systems which support files of > 64K bytes in size will support form (1) of the function, using both high and low offset values. Smaller operating systems may only support form (2) of the function, allowing seeking of only +/- 32K bytes. Also, some implementations may not support all "modes", or may only allow unsigned (positive) offsets. EXAMPLES: fseek(in_file, 0, 2); /* Advance to end of file */ FTELL FTELL PROTOTYPE: (1) int ftell(FILE *fp, int &h_offset, unsigned &l_offset) (2) int ftell(FILE *fp, int &offset) ARGUMENTS: fp - File pointer to an open file h_offset- Address of int to receive high word of offset l_offset- Address of int to receive low word of offset offset - Address of int to receive offset RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: This function gets the current read/write position within a file. The position returned indicates the absolute character (byte) offset from the start of the file where the next read or write will take place. Most operating systems which support files of > 64K bytes in size will support form (1) of the function, returning both high and low offset values. Smaller operating systems may only support form (2) of the function, allowing access to only the first 65535 character positions. EXAMPLES: ftell(fp, &oldh, &oldl); /* Save file position */ . . . /* Perform some operations on the file */ fseek(fp, oldh, oldl, 0); /* Return to previous position */ GETC GETC PROTOTYPE: int getc(FILE *fp) ARGUMENTS: fp - File pointer to an input file RETURN VALUE: Value of a character read from the file (0-255) EOF (-1) if end of file or an error condition occurs DESCRIPTION: This function reads a single character from an input file, and returns it as a positive value in the range of 0 to 255. A full 16 bit value is returned, allowing the end of file condition to be distinct from the character value 255. EXAMPLES: if((c = getc(input_file)) < 0) abort("End of file encountered\n"); GETDIR GETDIR PROTOTYPE: int getdir(char pathname[]) ARGUMENTS: pathname- Address of string to receive directory path RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: This function retreives from the system the name of the "current" directory path. The "pathname" string must be long enough to hold the largest pathname supported by the system, as indicated by the "PATH_SIZE" definition in the "file.h" header file. EXAMPLES: getdir(¤t_dir); GETENV GETENV PROTOTYPE: int getenv(char *ename, char *dest) ARGUMENTS: ename - String containing name of environment variable dest - Buffer to receive variable string value RETURN VALUE: 1 if environment variable was found, 0 if not. DESCRIPTION: The GETENV function gets the value of a variable in the programs environment, and returns it as a string. If the environment variable is not found, zero is returned, and the destination buffer is set to a null (zero length) string. Use of this function allows a programs fixed parameters and options to be specified once in environment variables, which may then be extracted by the program, eliminating the need to specify those values every time the program is executed. When operating MICRO-C under operating systems which do not support environment variables, this function will not be available. EXAMPLES: if(!getenv("COMSPEC", command)) abort("No command processor defined\n"); IN IN PROTOTYPE: int in(unsigned port) ARGUMENTS: port - I/O port address RETURN VALUE: The 8 bit value read from the given I/O port address DESCRIPTION: The "in" function reads and returns a byte (8 bits) from an I/O port as an integer value between 0 and 255. The valid range of values for "port" depends on the I/O address space of the processor. This function is not provided for processors which do not support a separate I/O address space. EXAMPLES: while(in(0)); /* Wait for flag to clear */ INW INW PROTOTYPE: int inw(unsigned port) ARGUMENTS: port - I/O port address RETURN VALUE: The 16 bit value read from the given I/O port address DESCRIPTION: The "inw" function reads and returns a word (16 bits) from an I/O port as an integer value between 0 and 65535 (-1). The valid range of values for "port" depends on the I/O address space of the processor. This function is not provided for processors which do not support a separate I/O address space. EXAMPLES: var = inw(0); ISALNUM ISALNUM PROTOTYPE: int isalnum(char c) ARGUMENTS: c - Any character value RETURN VALUE: 1 if 'c' is alphabetic or numeric 0 if 'c' is not alphabetic or numeric DESCRIPTION: Returns TRUE (1) if the passed character 'c' is an ASCII alphabetic letter in either upper or lower case or if 'c' is a numeric digit, otherwise FALSE (0) is returned. EXAMPLES: while(isalnum(*ptr)) /* Copy over symbol name */ *name++ = *ptr++; ISALPHA ISALPHA PROTOTYPE: int isalpha(char c) ARGUMENTS: c - Any character value RETURN VALUE: 1 if 'c' is alphabetic 0 if 'c' is not alphabetic DESCRIPTION: Returns TRUE (1) if the passed character 'c' is an ASCII alphabetic letter in either upper or lower case, otherwise FALSE (0) is returned. EXAMPLES: flag = isalpha(input_char); ISCNTRL ISCNTRL PROTOTYPE: int iscntrl(char c) ARGUMENTS: c - Any character value RETURN VALUE: 1 if 'c' is a "control" character 0 if 'c' is not a "control" character DESCRIPTION: Returns TRUE (1) is the passed character 'c' is an ASCII "control" character (0x00-0x1F or 0x7F), otherwise FALSE (0) is returned. EXAMPLES: putc(iscntrl(c) ? '.' : c, stdout); /* Display controls as '.' */ ISDIGIT ISDIGIT PROTOTYPE: int isdigit(char c) ARGUMENTS: c - Any character value RETURN VALUE: 1 if 'c' is numeric 0 if 'c' is not numeric DESCRIPTION: Returns TRUE (1) is the passed character 'c' is an ASCII digit ('0'-'9'), otherwise FALSE (0) is returned. EXAMPLES: value = 0; while(isdigit(*ptr)) value = (value * 10) + (*ptr++ - '0'); ISGRAPH ISGRAPH PROTOTYPE: int isgraph(char c) ARGUMENTS: c - Any character value RETURN VALUE: 1 if 'c' is a non-space printable character 0 if 'c' is a space or not printable DESCRIPTION: Returns TRUE (1) if the passed character 'c' is a printable ASCII character other than a space character, otherwise FALSE (0) is returned. EXAMPLES: putc(isgraph(c) ? c : '.', stdout); ISLOWER ISLOWER PROTOTYPE: int islower(char c) ARGUMENTS: c - Any character value RETURN VALUE: 1 if 'c' is lower case alphabetic 0 if 'c' is not lower case alphabetic DESCRIPTION: Returns TRUE (1) if the passed character 'c' is an ASCII alphabetic letter of lower case, otherwise FALSE (0) is returned. EXAMPLES: flag = islower(input_char); ISPUNCT ISPUNCT PROTOTYPE: int ispunct(char c) ARGUMENTS: c - Any character value RETURN VALUE: 1 if 'c' is a printable non-alphanumeric character 0 if 'c' is not printable or alphanumeric DESCRIPTION: Returns TRUE (1) if the passed character 'c' is a printable ASCII character which is not a letter of the alphabet or a numeric digit, otherwise FALSE (0) is returned. EXAMPLES: while(ispunct(*ptr)) ++ptr; ISSPACE ISSPACE PROTOTYPE: int isspace(char c) ARGUMENTS: c - Any character value RETURN VALUE: 1 if 'c' is a space character (space, tab or newline) 0 if 'c' is not a space character DESCRIPTION: Returns TRUE (1) if the passed character 'c' is one of a space, tab or newline, otherwise FALSE (0) is returned. EXAMPLES: while(isspace(*ptr)) ++ptr; ISUPPER ISUPPER PROTOTYPE: int isupper(char c) ARGUMENTS: c - Any character value RETURN VALUE: 1 if 'c' is upper case alphabetic 0 if 'c' is not upper case alphabetic DESCRIPTION: Returns TRUE (1) if the passed character 'c' is an ASCII alphabetic letter of upper case, otherwise FALSE (0) is returned. EXAMPLES: flag = isupper(input_char); LONGJMP LONGJMP PROTOTYPE: longjmp(int savenv[3], int rvalue) ARGUMENTS: savenv - Save area for program context rvalue - Value to be returned by "setjmp" RETURN VALUE: N/A - Function never returns DESCRIPTION: The "longjmp" function causes execution to transfer to the "setjmp" call which set up the "savenv" variable. The "setjmp" function will appear to return the value of "rvalue". NOTE-1: "longjmp" may only be used from within the function calling "setjmp" or a function which has been called "beneath" that function. IT MUST NOT BE USED AFTER THE FUNCTION CALLING "SETJMP" HAS TERMINATED. NOTE-2: If "rvalue" is zero, the function calling "setjmp" will assume that it is returning from initialization. Unless you want this unusual behavior, you should not pass a return value of zero to "longjmp". See also SETJMP. EXAMPLES: if(getc(stdin) == ('C'-'@')) /* If Control-C entered... */ longjmp(savearea, 1); /* Return to main function */ MALLOC MALLOC PROTOTYPE: char *malloc(int size) ARGUMENTS: size - Size of memory block to allocate (in bytes). RETURN VALUE: 0 - Memory allocation failed !0 - Pointer to allocated memory block DESCRIPTION: The "malloc" function allocates a block of memory of the specified size from the heap, and returns a pointer to it. This memory will remain allocated until it is explicitly releases with the "free" function. EXAMPLES: if(!(ptr = malloc(BUFSIZ))) /* Allocate a temporary buffer */ abort("Not enough memory"); do { /* Copy the file over */ size = fget(ptr, BUFSIZ, in_fp); fput(ptr, size, out_fp); } while(size == BUFSIZ); free(ptr); /* Release temporary buffer */ MAX MAX PROTOTYPE: int max(int value1, int value2) ARGUMENTS: value1 - Any integer value value2 - Any integer value RETURN VALUE: The greater of "value1" or "value2" DESCRIPTION: The "max" function returns the higher of its two argument values. EXAMPLES: biggest = max(a, b); MEMCPY MEMCPY PROTOTYPE: memcpy(char *dest, char *source, unsigned size) ARGUMENTS: dest - Pointer to the destination source - Pointer to the souce size - Number of bytes to copy RETURN VALUE: None DESCRIPTION: The "memcpy" function will copy the specified number of bytes from the source to the destination. EXAMPLES: memcpy(buffer1, buffer2, 256); MEMSET MEMSET PROTOTYPE: memset(char *block, char value, unsigned size) ARGUMENTS: block - Pointer to a block of memory value - Value to initialize memory with size - Number of bytes to initialize RETURN VALUE: None DESCRIPTION: Sets a block of memory beginning at the pointer "block", for "size" bytes to the byte value "value". EXAMPLES: memset(buffer, 0, 100); MIN MIN PROTOTYPE: int min(int value1, int value2) ARGUMENTS: value1 - Any integer value value2 - Any integer value RETURN VALUE: The smaller of "value1" or "value2" DESCRIPTION: The "min" function returns the lower of its two argument values. EXAMPLES: least = min(a, b); MKDIR MKDIR PROTOTYPE: int mkdir(char *pathname) ARGUMENTS: pathname- Name of directory to create RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: The "mkdir" function create a new directory on the disk under the specified path name. EXAMPLES: mkdir("subdir"); NARGS NARGS PROTOTYPE: int nargs() ARGUMENTS: None RETURN VALUE: The number of arguments passed to the calling function DESCRIPTION: Returns the number of arguments passed to a "register" function. NOTE: When calling a "register" function, MICRO-C loads the accumulator with the number of arguments just prior to calling the function. This "nargs" routine is simply a null definition which returns with the same value in the accumulator as was there when it was called. Therefore "nargs" MUST BE THE FIRST ARITHMETIC ENTITY EVALUATED WITHIN THE REGISTER FUNCTION or the contents of the accumulator will be lost. Some examples of "register" definitions and the use of "nargs" may be found in the library source code. EXAMPLES: first_arg = nargs() * 2 + &arguments; OUT OUT PROTOTYPE: out(unsigned port, int value) ARGUMENTS: port - I/O port address value - Value to write to I/O port RETURN VALUE: None DESCRIPTION: The "out" function writes a byte (8 bit) value to an I/O port. The valid range of values for "port" depends on the I/O address space of the processor. This function is not provided for processors which do not support a separate I/O address space. EXAMPLES: out(0, 0); /* Output 0 to I/O port 0 */ OUTW OUTW PROTOTYPE: outw(unsigned port, int value) ARGUMENTS: port - I/O port address value - Value to write to I/O port RETURN VALUE: None DESCRIPTION: The "outw" function writes a word (16 bit) value to an I/O port. The valid range of values for "port" depends on the I/O address space of the processor. This function is not provided for processors which do not support a separate I/O address space. EXAMPLES: outw(0, 0); /* Write 0 to I/O ports 0 and 1 */ PEEK PEEK PROTOTYPE: (1) int peek(unsigned address) (2) int peek(unsigned h_addr, unsigned l_addr) (3) int peek(unsigned segment, unsigned offset) ARGUMENTS: segment - Memory segment offset - Offset into segment h_addr - High word of memory address l_addr - Low word of memory address address - 16 bit memory address RETURN VALUE: The 8 bit value read from the given memory address DESCRIPTION: The "peek" function reads and returns a byte (8 bits) from memory as an integer value between 0 and 255. Processors such as the 8080 or 6809 which address 64K of memory or less use form (1) of the function. Non-segmented processors addressing more than 64K such as the 68000 use form (2) of the function. Processors employing a "segmented" architecture such as the 8086 use form (3) of the function. EXAMPLES: while(peek(0)); /* Wait for flag to clear */ PEEKW PEEKW PROTOTYPE: (1) int peekw(unsigned address) (2) int peekw(unsigned h_addr, unsigned l_addr) (3) int peekw(unsigned segment, unsigned offset) ARGUMENTS: segment - Memory segment offset - Offset into segment h_addr - High word of memory address l_addr - Low word of memory address address - 16 bit memory address RETURN VALUE: The 16 bit value read from the given memory address DESCRIPTION: The "peekw" function reads and returns a word (16 bits) from memory as an integer value between 0 and 65535 (-1). Processors such as the 8080 or 6809 which address 64K of memory or less use form (1) of the function. Non-segmented processors addressing more than 64K such as the 68000 use form (2) of the function. Processors employing a "segmented" architecture such as the 8086 use form (3) of the function. EXAMPLES: var = peekw(0)); POKE POKE PROTOTYPE: (1) poke(unsigned address, int value) (2) poke(unsigned h_addr, unsigned l_addr, int value) (3) poke(unsigned segment, unsigned offset, int value) ARGUMENTS: segment - Memory segment offset - Offset into segment h_addr - High word of memory address l_addr - Low word of memory address address - 16 bit memory address value - Value to be written to memory RETURN VALUE: None DESCRIPTION: The "poke" function writes a byte (8 bit) value to memory. Processors such as the 8080 or 6809 which address 64K of memory or less use form (1) of the function. Non-segmented processors addressing more than 64K such as the 68000 use form (2) of the function. Processors employing a "segmented" architecture such as the 8086 use form (3) of the function. EXAMPLES: poke(0, 0); /* Write 0 to location 0 */ POKEW POKEW PROTOTYPE: (1) pokew(unsigned address, int value) (2) pokew(unsigned h_addr, unsigned l_addr, int value) (3) pokew(unsigned segment, unsigned offset, int value) ARGUMENTS: segment - Memory segment offset - Offset into segment h_addr - High word of memory address l_addr - Low word of memory address address - 16 bit memory address value - Value to be written to memory RETURN VALUE: None DESCRIPTION: The "pokew" function writes a word (16 bit) value to memory. Processors such as the 8080 or 6809 which address 64K of memory or less use form (1) of the function. Non-segmented processors addressing more than 64K such as the 68000 use form (2) of the function. Processors employing a "segmented" architecture such as the 8086 use form (3) of the function. EXAMPLES: pokew(0, 0); /* Write 0 to locations 0 and 1 */ PRINTF PRINTF PROTOTYPE: register printf(char *format, arg, ...) ARGUMENTS: format - Pointer to format string arg - Argument as determined by format string ... - Additional arguments may be required RETURN VALUE: None DESCRIPTION: The "printf" routine performs a formatted print to the standard output device (usually system console). The "format" string is written with the arguments substituted for special "conversion characters". See "fprintf" for more information on format strings. NOTE: This function uses a variable number of arguments, and must be declared as "register" (See "stdio.h"). EXAMPLES: printf("Hello world!!!\n"); printf("File '%s', has %u lines\n", filename, num_lines); PUTC PUTC PROTOTYPE: putc(char c, FILE *fp) ARGUMENTS: c - Any character value fp - File pointer to an output file RETURN VALUE: 0 if successful, otherwise an operating system error code DECRIPTION: This function writes the character 'c' to the file indicated by "fp". The "newline" (\n) character will be translated into whatever character(s) are required by the operating system to separate records in the file. EXAMPLES: putc('*', fp); putc('\n', stderr); RAND RAND PROTOTYPE: unsigned rand(unsigned limit) ARGUMENTS: limit - Maximum value to return RETURN VALUE: A pseudo-random number in the range of 0 to (limit-1) DESCRIPTION: The "rand" function calculates the next value of a pseudo-random sequence, based on a 16 bit unsigned "seed" value, which it maintains in the global variable "RAND_SEED". The new value is stored as the new seed value, and is then divided by the "limit" parameter, to obtain the remainder, which is returned. This results in a random number in the range of zero (0) to (limit - 1). Any particular sequence may be repeated, by reseting the "RAND_SEED" value. EXAMPLES: value = rand(52); RENAME RENAME PROTOTYPE: int rename(char *pathname, char *newname) ARGUMENTS: pathname- Name of file to rename newname - New name for file RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: This function changes the name of an existing file to the ASCII string specified by newname. EXAMPLES: rename("output.dat", "output.bak"); REWIND REWIND PROTOTYPE: int rewind(FILE *fp) ARGUMENTS: fp - File pointer to an open file RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: This function resets the operating system internal file pointer so than any subsequent read or writes will be at the beginning of the file. EXAMPLES: rewind(input_file); RMDIR RMDIR PROTOTYPE: int rmdir(char *pathname) ARGUMENTS: pathname- Name of directory to delete RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: This function removes a directory from the disk. On most systems, the directory must be empty (contains no files) otherwise the function will fail. EXAMPLES: rmdir("subdir"); SCANF SCANF PROTOTYPE: register int scanf(char *format, arg1, arg2, ...) ARGUMENTS: format - Pointer to format string arg - Argument as determined by format string ... - Additional arguments may be required RETURN VALUE: The number of successful matches EOF (-1) if end of file or an error condition occurs DESCRIPTION: The "scanf" function reads and scans a line from the standard input device (usually system console) for specific values. Values are read and assigned to the passed argument addresses according to special "conversion characters" in the "format" string. See "fscanf" for more information on format strings. NOTE: This function uses a variable number of arguments, and must be declared as "register". EXAMPLES: do printf("Please enter your First & Last names, and your age?"); while(scanf("%s %s %u", first_name, last_name, &age) != 3); SETJMP SETJMP PROTOTYPE: int setjmp(int savenv[3]) ARGUMENTS: savenv - Save area for program context RETURN VALUE: 0 is returned when actually called Value passed to "longjmp" is returned otherwise DESCRIPTION: When called, the "setjmp" function stores the current execution state of the program into the passed integer array, and returns the value zero. The "longjmp" function may then be used to return the program to the "setjmp" call. In this case, the value returned by "setjmp" will be the value which was passed to "longjmp". This allows the function containing "setjmp" to determine which call to "longjmp" transfered execution to it. See also LONGJMP. EXAMPLES: switch(setjmp(savearea)) { case 0 : printf("Longjmp has been set up"); break; case 1 : printf("Control-C Interrupt"); break; case 2 : printf("Reset command executed"); break; default: printf("Software error trap"); break; } SPRINTF SPRINTF PROTOTYPE: register sprintf(char *dest, char *format, arg, ...) ARGUMENTS: dest - Pointer to destination string format - Pointer to format string arg - Argument as determined by format string ... - Additional arguments may be required RETURN VALUE: None DESCRIPTION: The "sprintf" routine performs a formatted print to a string in memory. The "format" string is written to the destination string with the arguments substituted for special "conversion characters". See "fprintf" for more information on format strings. NOTE: This function uses a variable number of arguments, and must be declared as "register" (See "stdio.h"). EXAMPLES: sprintf(header_file, "/lib/%s.h", header_name); SQRT SQRT PROTOTYPE: int sqrt(unsigned value) ARGUMENTS: value - Number for which to calculate square root RETURN VALUE: The integer square root (rounded up) of the argument value DESCRIPTION: The SQRT function returns the smallest number which when multiplied by itself will give a number equal to or larger that the argument value. EXAMPLES: /* * Draw a circle about point (x, y) of radus (r) */ circle(x, y, r) int x, y, r; { int i, j, k, rs, lj; rs = (lj = r)*r; for(i=0; i <= r; ++i) { j = k = sqrt(rs - (i*i)); do { plot_xy(x+i, y+j); plot_xy(x+i, y-j); plot_xy(x-i, y+j); plot_xy(x-i, y-j); } while(++j < lj); lj = k; } } SSCANF SSCANF PROTOTYPE: register int sscanf(char *input, char *format, arg1, arg2, ...) ARGUMENTS: input - Pointer to input string format - Pointer to format string arg - Argument as determined by format string ... - Additional arguments may be required RETURN VALUE: The number of successful matches DESCRIPTION: The "sscanf" function scans a string in memory for specific values. Values are read and assigned to the passed argument addresses according to special "conversion characters" in the "format" string. See "fscanf" for more information on format strings. NOTE: This function uses a variable number of arguments, and must be declared as "register". EXAMPLES: sscanf(pathname,"/%s/%s", directory, filename); STRBEG STRBEG PROTOTYPE: int strbeg(char *string1, char *string2) ARGUMENTS: string1 - Pointer to character string to test string2 - Pointer to character string to check for RETURN VALUE: 0 - String1 does not begin with string2 1 - String1 begins with string2 DECRIPTION: Tests the passed "string1" to determine if it begins with the same data as is contained within "string2". EXAMPLES: if(strbeg(command, "delete")) delete_file(&command[6]); STRCAT STRCAT PROTOTYPE: char *strcat(char *dest, *source) ARGUMENTS: dest - Pointer to destination string source - Pointer to source string RETURN VALUE: Pointer to zero terminating destination string DESCRIPTION: This function concatinates the source string onto the tail of the destination string. The destination string must be large enough to hold the entire contents of both strings. EXAMPLES: strcat(program_name, ".c"); STRCHR STRCHR PROTOTYPE: char *strchr(char *string, char chr) ARGUMENTS: string - Pointer to a character string chr - Character to look for RETURN VALUE: Pointer to the first occurance of 'chr' in 'string' Zero (0) if character was not found DECRIPTION: Searches the passed string got the first occurance of the specified character. If the character is found, a pointer to its position in the string is returned. If the character is not found, a null pointer is returned. The null (0) character is treated as valid data by this function, thus: strchr(string, 0); would return the position of the null terminator of the string. EXAMPLES: comma = strchr(buffer, ','); STRCMP STRCMP PROTOTYPE: int strcmp(char *string1, char *string2) ARGUMENTS: string1 - Pointer to first string string2 - Pointer to second string RETURN VALUE: 0 - Strings match exactly 1 - String1 is greater than string2 -1 - String2 is greater than string1 DESCRIPTION: This function compares two strings character by character. If the two strings are identical, a zero (0) is returned. If the first string is greater than the second (as far as ASCII is concerned), a one (1) is returned. If the second string is greater, a negative one (-1) is returned. EXAMPLES: if(!strcmp(command, "quit")) exit(0); STRCPY STRCPY PROTOTYPE: char *strcpy(char *dest, char *source) ARGUMENTS: dest - Pointer to destination string souce - Pointer to source string RETURN VALUE: Pointer to zero terminating destination string DESCRIPTION: This function copies the source string to the destination string. All data is copied up to and including the zero byte which terminates the string. The destination string must be large enough to hold the entire source. EXAMPLES: strcpy(filename, argv[1]); STRLEN STRLEN PROTOTYPE: int strlen(char *string) ARGUMENTS: string - Pointer to a character string RETURN VALUE: The length of the string DECRIPTION: Returns the length in character of the passed string. The length does not include the zero byte which terminates the string. EXAMPLES: length = strlen(command); STRNCAT STRNCAT PROTOTYPE: char *strncat(char *dest, *source, unsigned length) ARGUMENTS: dest - Pointer to destination string source - Pointer to source string length - Maximum number of characters to copy RETURN VALUE: Pointer to zero terminating destination string DESCRIPTION: This function concatinates the source string onto the tail of the destination string. If the source string exceeds "length" bytes in size, only that many characters are copied. EXAMPLES: strncat(path, filename, 64); STRNCMP STRNCMP PROTOTYPE: int strncmp(char *string1, char *string2, unsigned length) ARGUMENTS: string1 - Pointer to first string string2 - Pointer to second string length - Number of bytes to compare RETURN VALUE: 0 - Strings match exactly 1 - String1 is greater than string2 -1 - String2 is greater than string1 DESCRIPTION: This function compares two strings character by character until either a difference is detected, or "length" characters have been compared. If the two string portions are identical, a zero (0) is returned. If the first string is greater than the second (as far as ASCII is concerned), a one (1) is returned. If the second string is greater, a negative one (-1) is returned. EXAMPLES: len = strlen(buffer) - 3; for(i=1; i < len; ++i) if(strncmp(&buffer[i], "***", 3) abort("Found three stars\n"); STRNCPY STRNCPY PROTOTYPE: strncpy(char *dest, char *source, unsigned length) ARGUMENTS: dest - Pointer to destination string souce - Pointer to source string length - Number of bytes to copy RETURN VALUE: None DESCRIPTION: This function copies "length" characters from the source string to the destination string. If the source string is shorter than "length", the destination string is padded with nulls. If the source string is longer than "length", only that many characters are copied, and the destination string is NOT zero terminated. EXAMPLES: strncpy(filename, argv[1], 64); STRSTR STRSTR PROTOTYPE: char *strstr(char *string1, char *string2) ARGUMENTS: string1 - Pointer to character string to test string2 - Pointer to substring to search for RETURN VALUE: Pointer to substring, or 0 if not found DECRIPTION: Searches the passed "string1" for the first occurance of the passed "string2". If found, a pointer to the beginning of that substring within "string1" is returned. EXAMPLES: if(ptr = strstr(command, "delete")) delete_file(&ptr[6]); SYSTEM SYSTEM PROTOTYPE: int system(char *command) ARGUMENTS: command - A system command to be executed RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: The SYSTEM function accepts any operating system command as a string parameter, and passes that command to the operating system to be executed. When the command has terminated, execution will resume in the MICRO-C program, with the statement following the call to SYSTEM. EXAMPLES: system("DEL *.TMP"); TOLOWER TOLOWER PROTOTYPE: char tolower(char c) ARGUMENTS: c - Any character value RETURN VALUE: The value of 'c', converted to lower case DESCRIPTION: Returns the value of 'c' converted to lower case. If 'c' is not a letter of upper case, no change is made, and the original value of 'c' is returned. EXAMPLES: input_char = tolower(getc(stdin)); TOUPPER TOUPPER PROTOTYPE: char toupper(char c) ARGUMENTS: c - Any character value RETURN VALUE: The value of 'c', converted to upper case DESCRIPTION: Returns the value of 'c' converted to upper case. If 'c' is not a letter of lower case, no change is made, and the original value of 'c' is returned. EXAMPLES: putc(toupper(output_char), stdout); MICRO-C Page: 61 10.2 IBM-PC/MS-DOS Library Functions The following functions are available only under the MS-DOS operating system, on IBM-PC or compatible systems. These routines perform operations which are closely tied to the 8086 family of processors, the IBM-PC hardware, or the MS-DOS operating system, and are therefore impractical to implement on a "general" basis. ALLOC_SEG ALLOC_SEG PROTOTYPE: int alloc_seg(int size) ARGUMENTS: size - Number of 16 byte paragraphs to allocate RETURN VALUE: 0 - Not enough free memory available !0 - The segment address of the allocated memory DESCRIPTION: The "alloc_seg" function allocates a 'segment' of memory from DOS. The size is given in 16 byte "paragraphs". The allocated memory will be outside of the data memory available to the MICRO-C program, and therefore must be accessed via assembly lenguage functions, or with the "peek" and "poke" library functions. EXAMPLES: if(!(aseg = alloc(4096))) /* Get a 64K data segment */ abort("Not enough memory!!!"); set_es(aseg); /* Set up extra segment */ asm_func(); /* Invoke assembler function */ CCLOSE CCLOSE PROTOTYPE: Cclose() ARGUMENTS: None RETURN VALUE: None DESCRIPTION: This function closes the communications port previously opened using "Copen". The system interrupt vectors and all other hooks to the comm port are restored. This function must be called before any program using "Copen" terminates, otherwise the communications port will be left in an indeterminate state. If this is not done, there will be a possibility of system crash if an interrupt is received from the port after the program has terminated. EXAMPLES: Cclose(); /* Close comm port */ exit(0); /* And terminate */ CGETC CGETC PROTOTYPE: int Cgetc() ARGUMENTS: None RETURN VALUE: Character read from the communications port DESCRIPTION: This function reads a single character from the communications port previously opened with "Copen". If no character is available, "Cgetc" will wait for one. EXAMPLES: /* Get a string from the comm port */ while((c = cgetc()) != '\r') *ptr++ = c; *ptr = 0; COPEN COPEN PROTOTYPE: int Copen(int port, int speed, int mode, int modem) ARGUMENTS: port - Comm port to use (1 or 2) speed - Baudrate divisor to set mode - Communications parameters to set modem - Modem control lines to set RETURN VALUE: 0 - Successful open !0 - Requested comm port is not available DESCRIPTION: The "Copen" function opens a serial communications port on the IBM PC for access. An independant interrupt handler and I/O drivers are installed, which allow high speed full duplex operation of the serial port with optional XON/XOFF flow control of both receive and transmit streams. Only one serial port may be accessed at a time using these functions, If "Copen" is called more than once, it will automatically close the last port before opening the new one. The meaning of the "speed", "mode", and "modem" parameters if documented in the "comm.h" header file. An external "char" variable "Cflags" may be accessed to enable or disable transparency of the serial channel. When "transparent" is selected, XON/XOFF flow control is disabled, and all data is sent and received with no changes. When operating in this mode, you must insure that "Cgetc" is called frequently enough that the 256 byte internal receive buffer will not overflow. Since "Cflags" is used by the interrupt handler, you should disable and enable interrupts around any accessed to it. EXAMPLES: #include comm.h /* Get comm port defintions */ extern char Cflags; /* * Program to read & echo characters on the serial port * in transparent mode. (Until ESCAPE char is received) */ main() { char c; if(Copen(1, _2300, PAR_NO|DATA_8|STOP_1, SET_RTS|SET_DTR)) abort("Cannot access COM1"); disable(); /* Disable interrupts */ Cflags |= TRANSPARENT; /* Set transparency */ enable(); /* Re-enable interrupts */ while((c = Cgetc()) != 0x1B) /* Do until ESCAPE */ Cputc(c); Cclose(); /* Close the serial port */ } COPY_SEG COPY_SEG PROTOTYPE: copy_seg(int dseg, int doffset, int sseg, int soffset, int size) ARGUMENTS: dseg - Destination segment doffset - Destination offset sseg - Source segment soffset - Source offset size - Number of bytes to copy RETURN VALUE: None DESCRIPTION: This function perform a copy between 80X86 processor memory segments. A number of bytes equal to "size" is copied from the source segment and offset to the destination segment and offset. EXAMPLES: /* Save the video display contents */ copy_seg(get_ds(), buffer, _V_BASE, 0, (25*80)*2); CPU CPU PROTOTYPE: int cpu() ARGUMENTS: None RETURN VALUE: 0 - CPU is 8088 or 8086 1 - CPU is 80188 or 80186 2 - CPU is 80286 3 - CPU is 80386 or 80486 DESCRIPTION: This function returns a simple integer which identifies the processor type on which the program is currently executing. EXAMPLES: if(cpu() < 2) abort("This program requires at least an 80286"); CPUTC CPUTC PROTOTYPE: Cputc(char c) ARGUMENTS: c - Character to write to communciation port RETURN VALUE: None DESCRIPTION: The "Cputc" function writes the given character to the communcinations port previously opened by "Copen". EXAMPLES: while(*ptr) /* Write a string to comm port */ Cputc(*ptr++); CSIGNALS CSIGNALS PROTOTYPE: int Csignals() ARGUMENTS: None RETURN VALUE: The modem input signals read from the open comm port DESCRIPTION: This function reads the modem input signals (DSR, CD, RI etc) from the serial communication port previously opened by "Copen", and returns them as an integer value. The meaning of the individual bits in the value returned by "Csignals" is documented in the "comm.h" header file. EXAMPLES: if(!(Csignals() & DSR)) { Cclose(); abort("Modem not ready"); } CTESTC CTESTC PROTOTYPE: int Ctestc() ARGUMENTS: None RETURN VALUE: 0-255 - Character read from comm port -1 - No character available DESCRIPTION: This function tests for a character from the communications port previously opened with "Copen", and returns that character if one if found. If no character is available, "Ctestc" returns -1. EXAMPLES: if((c = Ctestc()) == -1) { Cclose(); abort("No character available"); } DISABLE DISABLE PROTOTYPE: disable(); ARGUMENTS: None RETURN VALUE: None DESCRIPTION: The "disable" function disables the 8086 interrupt system, preventing the processor from servicing interrupts. It is used whenever the execution of an interrupt handler may interfere with a particular operation. When this function is used, the "enable" function should be called as soon as possible after "disable". Failure to do this may result in loss of system functions performed under interrupts, such as timekeeping, and serial communications (Via MICRO-C serial drivers). EXAMPLES: disable(); /* Disallow interrupts */ Cflags &= ~TRANSPARENT; /* Remove transparency */ enable(); /* Re-allow interrupts */ ENABLE ENABLE PROTOTYPE: enable(); ARGUMENTS: None RETURN VALUE: None DESCRIPTION: The "enable" function enables the 8086 interrupt system, allowing the processor to service interrupts. It should be called as soon as possible following the use of the "disable" function. EXAMPLES: disable(); /* Disallow interrupts */ Cflags |= TRANSPARENT; /* Force transparency */ enable(); /* Re-allow interrupts */ EXEC EXEC PROTOTYPE: int exec(char *exefile, char *args) ARGUMENTS: exefile - Full pathname of a '.COM' or '.EXE' file args - Command tail containing arguments RETURN VALUE: 0 if successful, otherwise an MS-DOS error code DESCRIPTION: The "exec" function causes MS-DOS to suspend the execution of the MICRO-C program, and then to execute the indicated '.EXE' or '.COM' program file. When that program terminates, execution of the MICRO-C program will resume. This is a low level interface to the MS-DOS 'EXEC' function, and as such, it does not search your PATH, does not process '.BAT' files, nor provide any I/O redirection facilities. If you want to make use of these features (which are provided by 'COMMAND.COM'), use the higher level 'SYSTEM' function. EXAMPLES: printf("Type 'EXIT' to return to the MICRO-C program\n"); exec("C:\\COMMAND.COM", ""); /* Start up a sub-shell */ FREE_SEG FREE_SEG PROTOTYPE: int free_seg(int segment) ARGUMENTS: segment - A previously allocated segment of memory RETURN VALUE: 0 - The segment was released !0 - DOS error code DESCRIPTION: The "free_seg" function releases a segment of memory previously allocated by "alloc_seg", and returns it to the operating system. This should be used whenever your program has finished with a segment of extra memory which it has allocated. EXAMPLES: aseg = alloc_seg(4096); /* Allocate a 64K segment */ set_es(aseg); /* Set up extra segment */ asm_func(); /* Call assembler function */ free_seg(aseg); /* Releas the memory */ GET_ATTR GET_ATTR PROTOTYPE: int get_attr(char *pathname, int &attrs) ARGUMENTS: pathname- Name of file to get attributes of attrs - Integer to receive attributes RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: This function retreives the attributes of the specified file. The meaning of the individual bits in the "attrs" value is defined in the "file.h" header file. EXAMPLES: get_attr("tempfile", &attributes); GET_CS GET_CS PROTOTYPE: int get_cs() ARGUMENTS: None RETURN VALUE: The current processor CODE segment DESCRIPTION: This function is available only on the 8086 family of processors, and returns the current processor CODE segment. EXAMPLES: code_seg = get_cs(); GET_DATE GET_DATE PROTOTYPE: get_date(int &day, int &month, int &year) ARGUMENTS: &day - Address of integer to receive day (1-31) &month - Address of integer to receive month (1-12) &year - Address of integer to receive year (1980-2099) RETURN VALUE: None DESCRIPTION: This function gets the current system date in day, month, and year. EXAMPLES: get_date(&day, &month, &year); printf("%s %u, %u", months[month], day, year); GET_DRIVE GET_DRIVE PROTOTYPE: int get_drive() ARGUMENTS: None RETURN VALUE: The currently active (default) disk drive (0=A, 1=B, 2=C, ...) DESCRIPTION: The "get_drive" function returns the drive index (0-n) of the currently active or "default" MS-DOS disk drive. EXAMPLES: old_drive = get_drive(); set_drive(new_drive); GET_DS GET_DS PROTOTYPE: int get_ds() ARGUMENTS: None RETURN VALUE: The current processor DATA segment DESCRIPTION: This function is available only on the 8086 family of processors, and returns the current processor DATA segment. EXAMPLES: data_seg = get_ds(); GET_ES GET_ES PROTOTYPE: int get_es() ARGUMENTS: None RETURN VALUE: The current processor EXTRA segment DESCRIPTION: This function is available only on the 8086 family of processors, and returns the current processor EXTRA segment. EXAMPLES: code_seg = get_es(); GET_TIME GET_TIME PROTOTYPE: get_time(int &hour, int &minite, int &second) ARGUMENTS: &hour - Address of integer to receive hour (0-23) &minite - Address of integer to receive minite (0-59) &second - Address of integer to receive second (0-59) RETURN VALUE: None DESCRIPTION: This function gets the current system time in hours, minites and seconds. EXAMPLES: get_time(&hour, &minite, &second); printf("%02:%02:%02", hour, minite, second); RESIZE_SEG RESIZE_SEG PROTOTYPE: int resize_seg(int segment, int size) ARGUMENTS: segment - A previously allocated segment of memory size - Desired size (in 16 byte paragraphs) RETURN VALUE: 0 - The segments size has been adjusted !0 - DOS error code DESCRIPTION: The "resize_seg" function provides a method of changing the size of a segment of memory previously allocated via "alloc_seg". If not enough memory is available, the function will fail with a ono-zero return value. This function may also be used to adjust the memoey allocation of the programs image, by passing it the segment address of the programs own PSP. This value is available in the external variable "PSP". MICRO-C normally allocates 64K for programs compiled in the TINY model, and (64K + (256 byte PSP) + (size of executable code)) for programs compiled in the SMALL model. This allocation should NEVER be reduced, however you may enlarge it if your program wishes to access additional data immediately following its own DATA/STACK segment. EXAMPLES: extern int PSP; main() { if(resize_seg(PSP, 8192)) /* Append 64K buffer */ abort("Not enough memory!!!"); ... /* Remainder of program */ } RESTORE_VIDEO RESTORE_VIDEO PROTOTYPE: restore_video(char buffer[4006]); ARGUMENTS: buffer - Video save area. RETURN VALUE: None DESCRIPTION: The RESTORE_VIDEO function restores the contents and state of the IBM P.C. video display to the state it was in when "SAVE_VIDEO" was executed. At the present time, the function is effective only for text modes. Graphics screens will not be restored, due to the high memory requirements. Although this function is useful in ANY program (to restore the DOS screen before termination), it is most useful in "POP-UP" ram resident programs (See "TSR" function), to save the screen of any application which may be running when you pop up. The video state is restored from the passed "buffer" argument, which is 4006 bytes in size, and must have been filled in by "SAVE_VIDEO". It has the following format: buffer[0] - Video mode " [1] - Video page " [2] - 'X' cursor position " [3] - 'Y' cursor position " [4] - Ending line for cursor " [5] - Starting line for cursor " [6-4005] - Saved video screen contents EXAMPLES: popup_func() { save_video(); perform_function(); restore_video(); } SAVE_VIDEO SAVE_VIDEO PROTOTYPE: save_video(char buffer[4006]); ARGUMENTS: buffer - Video save area. RETURN VALUE: None DESCRIPTION: The SAVE_VIDEO function saves the current contents and state of the IBM P.C. video display. The screen may be restored at any time using "RESTORE_VIDEO". At the present time, the function is effective only for text modes. Graphics screens will not be saved, due to the high memory requirements. Although this function is useful in ANY program (to restore the DOS screen before termination), it is most useful in "POP-UP" ram resident programs (See "TSR" function), to save the screen of any application which may be running when you pop up. The video state is saved in the passed "buffer" argument, which is 4006 bytes in size, and has the following format: buffer[0] - Video mode " [1] - Video page " [2] - 'X' cursor position " [3] - 'Y' cursor position " [4] - Ending line for cursor " [5] - Starting line for cursor " [6-4005] - Saved video screen contents EXAMPLES: popup_func() { save_video(); perform_function(); restore_video(); } SET_ATTR SET_ATTR PROTOTYPE: int set_attr(char *pathname, int attrs) ARGUMENTS: pathname- Name of file to get attributes of attrs - New attributes RETURN VALUE: 0 if successful, otherwise an operating system error code DESCRIPTION: This function sets the system attributes of the specified file. The meaning of the individual bits in the "attrs" value is defined in the "file.h" header file. EXAMPLES: set_attr("tempfile", READONLY|HIDDEN); SET_DATE SET_DATE PROTOTYPE: set_date(int day, int month, int year) ARGUMENTS: day - New day (1-31) month - New month (1-12) year - New year (1980-2099) RETURN VALUE: 0 - Success -1 - Invalid date given DESCRIPTION: This function sets the current system date to day, month, and year. EXAMPLES: set_date(1, 1, 1980); /* Set to Jan 1, 1980 */ SET_DRIVE SET_DRIVE PROTOTYPE: int set_drive(int drive) ARGUMENTS: Drive - New drive index (0=A, 1=B, 2=C ...) RETURN VALUE: The total number of "logical" disk drives in the system DESCRIPTION: The "set_drive" function sets the disk drive indicated by the "drive" index (0-x) to be the currently active or "default" MS-DOS disk drive. EXAMPLES: old_drive = get_drive(); set_drive(new_drive); SET_ES SET_ES PROTOTYPE: int set_es(int segment) ARGUMENTS: segment - The 16 bit new segment value RETURN VALUE: None DESCRIPTION: This function is available only on the 8086 family of processors, and sets the processors EXTRA segment to the indicated value. EXAMPLES: set_es(get_ds()); /* Copy DATA to EXTRA segments */ SET_TIME SET_TIME PROTOTYPE: set_time(int hour, int minite, int second) ARGUMENTS: hour - New hour (0-23) minite - New minite (0-59) second - New second (0-59) RETURN VALUE: 0 - Success -1 - Invalid time given DESCRIPTION: This function sets the current system time to "hour", "minite" and "second". EXAMPLES: set_time(0, 0, 0); /* Set to 00:00:00 (midnight) */ TSR TSR PROTOTYPE: tsr(&func, int hotkey, int alloc) ARGUMENTS: func - Address of function to execute hotkey - POP-UP activation hotkeys alloc - Memory allocation RETURN VALUE: Function normally never returns, but if it does, an operating system error code is passed back. DESCRIPTION: The TSR function terminates the MICRO-C program, but leaves it resident in memory. When the specified "HOT KEYS" are detected on the IBM PC keyboard, the context of whatever program is running is saved, and the specified MICRO-C function is called. When that function returns, the interrupted program is resumed. When activated this way, THE "func" FUNCTION MUST NOT TERMINATE WITH "exit" or one of its related functions (abort etc.). THE ONLY WAY IT MAY TERMINATE IS TO "return" NORMALLY. The meaning of "hotkey" is defined in the "tsr.h" header file. The "alloc" paremeter specifies how much extra memory is to be retained in the TSR image for use by the MICRO-C stack and heap memory allocation functions. The "func" function(s) must insure that the total amount of memory used by the stack and calls to "malloc" does not exceed this value. NOTE: "malloc" will fail if the heap grows to within 1K of the stack pointer. All memory used by code, global variables, string space, and "malloc" calls prior to the use of "tsr" is automatically retained, and should not be included in the "alloc" value. TSR programs which perform screen I/O should take care to save and restore the screen contents when popping up and down. EXAMPLES: tsr(&popup_func, ALT+L_SHIFT, 1024); VCLEAR_BOX VCLEAR_BOX PROTOTYPE: vclear_box(int x, int y, int w, int h) ARGUMENTS: x - COLUMN of top left corner of box y - ROW of top left corner of box w - Width of box (columns) h - Height of box (rows) RETURN VALUE: None DESCRIPTION: This function clears a box of the specified height and width, at the indicated 'X' and 'Y' coordinates, on the IBM-PC video screen using the block graphics characters. The entire box is cleared to spaces. "VOPEN" MUST be called prior to using this function. EXAMPLES: vclear_box(21, 11, 8, 3); /* Clear a BOX */ VCLEOL VCLEOL PROTOTYPE: vcleol() ARGUMENTS: None RETURN VALUE: None DESCRIPTION: This function clears the IBM PC video screen from the current cursor position to the end of a line. You must "#include video.h", and execute "VOPEN" prior to using this function. EXAMPLES: vprintf("Input> "); /* Display a prompt */ vcleol(); /* Clear remainder of input line */ VCLEOS VCLEOS PROTOTYPE: vcleos() ARGUMENTS: None RETURN VALUE: None DESCRIPTION: This function clears the IBM PC video screen from the current cursor position to the end of a screen. "VOPEN" MUST be called prior to using this function. EXAMPLES: vgotoxy(0, 10); /* position at line 11 */ vcleos(); /* Clear lower part of screen */ VCLSCR VCLSCR PROTOTYPE: vclscr() ARGUMENTS: None RETURN VALUE: None DESCRIPTION: This function clears the entire IBM PC video screen and resets the cursor position to the top left hand corner. "VOPEN" MUST be called prior to using this function. EXAMPLES: if(c = 0x1b) { /* Escape command */ vclscr(); /* Clear the screen */ vprintf("%s has terminated\n", argv[0]); exit(-1); } VCURSOR_BLOCK VCURSOR_BLOCK PROTOTYPE: vcursor_block() ARGUMENTS: None RETURN VALUE: None DESCRIPTION: This function enables (turns on) display of the cursor on the IBM PC video display. The cursor is shown as flashing block, occupying the entire character window. "VOPEN" MUST be called prior to using this function. EXAMPLES: if(insert) /* Test insert mode flag */ vcursor_block(); /* Indicate inserting with block cursor */ else vcursor_line(); /* Indicate overwrite with line cursor */ VCURSOR_LINE VCURSOR_LINE PROTOTYPE: vcursor_line() ARGUMENTS: None RETURN VALUE: None DESCRIPTION: This function enables (turns on) display of the cursor on the IBM PC video display. The cursor is shown as a single flashing line, at the bottom of the character window. "VOPEN" MUST be called prior to using this function. EXAMPLES: vcursor_line(); /* Re-enable the cursor */ exit(0); /* And terminate */ VCURSOR_OFF VCURSOR_OFF PROTOTYPE: vcursor_off() ARGUMENTS: None RETURN VALUE: None DESCRIPTION: This function inhibits (turns off) display of the cursor on the IBM PC video display. This affects the cursor display only, screen output will continue to be displayed at the correct cursor position. "VOPEN" MUST be called prior to using this function. EXAMPLES: vclscr(); /* Clear screen */ vcursor_off(); /* Inhibit cursor */ vmenu(10, 10, main_menu, 0, &index); /* Present main menu */ VDRAW_BOX VDRAW_BOX PROTOTYPE: vdraw_box(int x, int y, int w, int h) ARGUMENTS: x - COLUMN of top left corner of box y - ROW of top left corner of box w - Width of box (columns) h - Height of box (rows) RETURN VALUE: None DESCRIPTION: This function draws a box of the specified height and width, at the indicated 'X' and 'Y' coordinates, on the IBM-PC video screen using the block graphics characters. "VOPEN" MUST be called prior to using this function. EXAMPLES: vdraw_box(20, 10, 10, 5); /* Draw a BOX */ VERSION VERSION PROTOTYPE: int version() ARGUMENTS: None RETURN VALUE: MS-DOS operating system version number DESCRIPTION: The "version" function is available only under MS-DOS, and returns the version number of the operating system. The higher 8 bits of the returned value indicates the MAJOR version number ('3' in DOS 3.1) The lower 8 bits of the returned value indicates the MINOR version nuber ('1' in DOS 3.1). EXAMPLES: if(version() < 0x031E) abort("Requires DOS 3.30 or higher\n"); VGETC VGETC PROTOTYPE: int vgetc() ARGUMENTS: None RETURN VALUE: 0-127 - ASCII value of key pressed < 0 - Special function key as defined in "video.h" DESCRIPTION: The "vgetc" function waits until a key is pressed on the system console, and returns its value. Note that due to the buffering of the IBM-PC keyboard, every keypress will be reported, even if the VGETC function is called after a key is pressed and released. EXAMPLES: switch(vgetc()) { /* Handle input keys . . . } VGETS VGETS PROTOTYPE: int vgets(int x, int y, char *prompt, char *field, int width) ARGUMENTS: x - COLUMN of top left corner of input box y - ROW of top left corner of input box prompt - String to prompt with field - String to receive the data width - Width in characters of input field RETURN VALUE: 0 - Selection was made and ENTER pressed. !0 - Input was aborted via ESCAPE key. DESCRIPTION: The "vgets" function draws a box on the video screen at the specified X and Y coordinates, then prompts for and receives an input string in the box. The box is drawn large enough to contain the prompt and the specified width of input field. The prompt is displayed at the left hand side of the box, and the cursor is positioned immediatly following it, at the start of the input field. The "field" parameter is the address of a character array to receive the input string. The previous value of the "field" array is inserted into the input box when VGETS is invoked. If you do not want to display an old value, you should set the first character pointed to by field to zero, before calling VGETS. When entering the string, the user may use the following special keys to edit the input field: Right Arrow - Move forward one character Left Arrow - Move backward one character Delete - Delete the character under the cursor Backspace - Move backward one character and delete. Home - Move to beginning of string End - Move to end of string PgUp - Clear (erase) entire string PgDn - Clear from cursor to end of string Enter - Accept (enter) the string ESC - Abort the input request All data entered in the input box is inserted into any data which is already present. EXAMPLES: name[0] = 0; if(vgets(10, 10, "Your name?", name, 30)) return; /* Aborted, exit to higher level */ VGOTOXY VGOTOXY PROTOTYPE: vgotoxy(int x, int y) ARGUMENTS: x - New COLUMN (0-79) y - New ROW (0-24) RETURN VALUE: None DESCRIPTION: The "vgotoxy" function positions the cursor on the IBM-PC video screen. Any further display output will occur at the new ROW and COLUMN on the screen. The extern "int" variable "V_XY" may be referenced to read or set the current X/Y position. The higher 8 bits contain the 'Y' coordinate, and the lower 8 bits contain the 'X' coordinate. If this variable is used to set (restore) the cursor position, "vupdatexy" must then be called to position the physical cursor. "VOPEN" MUST be called prior to using this function. EXAMPLES: for(i=0; i<24; ++i) { /* Draw a diagonal line of 'X's */ vgotoxy(i, i); vputc('X'); } VMENU VMENU PROTOTYPE: vmenu(int x, int y, char *names[], char erase, int &index) ARGUMENTS: x - COLUMN of top left corner of menu box y - ROW of top left corner of menu box names - Array to menu selection text (last entry = 0) erase - 1=Erase BOX after selection is made index - Address of message selection index variable RETURN VALUE: 0 - Selection was made and ENTER pressed. !0 - Menu was aborted via ESCAPE key. DESCRIPTION: The "vmenu" function displays a list of menu items enclosed in a box on the IBM-PC video screen at the specified ROW and COLUMN address. The user may use the UP, DOWN, HOME and END keys to select an entry by moving the INVERSE VIDEO selection cursor. When the desired selection is under the cursor, the selection is made by pressing the ENTER key. At any time the menu selection may be canceled by pressing the ESCAPE key. The "names" argument must be a pointer to an array of character strings which are the selections to display. This array MUST end with a zero (0) element to indicate the end of the list. The "erase" flag indicates that the menu box should be cleared to blanks when the selection is made. If "erase=0", the menu box is left on the screen, WITHOUT the selection cursor, with the selected entry marked by '>' and '<'. The menu box is always erased when the menu is aborted with the ESCAPE key. The "index" argument is the address of an "int" variable which contains the position of the selection cursor. It controls where the selection cursor will appear when the function is first invoked (0 = first entry), and also is assigned the position of the selection cursor when the selection is made. EXAMPLES: char *names[] = { "One", "Two", "Three", "Four", "Five", 0 }; . . . index = 0; if(vmenu(10, 10, names, 0, &index)) return; /* Aborted, exit to higher level */ switch(index) { /* Handle selection */ . . . } VMESSAGE VMESSAGE PROTOTYPE: vmessage(int x, int y, char *string) ARGUMENTS: x - COLUMN of top left corner of message box y - ROW of top left corner of message box string - Message to display RETURN VALUE: None DESCRIPTION: The "vmessage" function displays a text string surrounded by a BOX, on the IBM-PC video screen, at the specified ROW and COLUMN address. "VOPEN" MUST be called prior to using this function. EXAMPLES: vmessage(20, 20, "Press any KEY to continue"); get_key(); vclear_box(20, 20, 26, 2); VOPEN VOPEN PROTOTYPE: vopen() ARGUMENTS: None RETURN VALUE: None DESCRIPTION: This function initializes the IBM-PC video display adapter for use with the MICRO-C video library functions. It determines the adapter type (COLOR ot MONOCHROME), sets up internal variables with information required by the other video functions, and clears the video screen. This function MUST be called before any of the other video functions in the library are used. After "vopen" is called, the extern "int" variable "V_BASE" may be referenced to determine the memory segment of the video display (B000 for monochrome, B800 for color). Any program using the video library functions must include the "video.h" header file. EXAMPLES: vopen(); VPRINTF VPRINTF PROTOTYPE: register vprintf(char *format, arg, ...) ARGUMENTS: format - Pointer to format string arg - Argument as determined by format string ... - Additional arguments may be required RETURN VALUE: None DESCRIPTION: This function performs exactly as the "PRINTF" function in the standard function library, except that it outputs directly to the video screen using the video interface library routines. This function should be used in preference to "PRINTF" when using the video function library since "PRINTF" will not move the video librarys cursor. NOTE: This function uses a variable number of arguments, and must be declared as "register" (See "video.h"). "VOPEN" MUST be called prior to using this function. EXAMPLES: vgotoxy(0, 0); vprintf("Screen %u", screen); VPUTC VPUTC PROTOTYPE: vputc(char chr) ARGUMENTS: chr - Character to display RETURN VALUE: None DESCRIPTION: This function displays a character on the video screen at the current cursor position. Characters are output in "tty" fashion, with proper handling of control codes such as CARRIAGE-RETURN, LINE-FEED and BELL. The screen will scroll upwards when a NEWLINE is printed on the bottom line of the screen, or when the bottom line wraps around to the next. Although only the lower 8 bits of a passed value are used, "vputc" will not perform ANY output translations if any of the upper 8 bits are set. This provides a method of displaying the video characters represented by control codes such as NEWLINE, and BACKSPACE. The external "char" variable "V_ATTR" may be used to set the video attribute used by "VPUTC" to display the character. This value is written to the attribute location associated with the character on the video display hardware. Its effect is dependant on the video adapter in use. The "video.h" header file contains definitions of the attribute bits for use on "standard" monochrome and color displays. "VOPEN" MUST be called prior to using this function. EXAMPLES: vputc(0x0A); /* Line-feed, advance cursor */ vputc(0x0A | 0xff00); /* Display 0x0A character code */ VPUTF VPUTF PROTOTYPE: vputf(char *string, int width) ARGUMENTS: string - Pointer to character string width - Width of output field RETURN VALUE: None DESCRIPTION: The "vputf" function outputs a character string to the IBM-PC video screen using the video library functions. The string is left justified in a field of the specified width. If the string is shorter than "width", the field is padded with blanks. If the string is longer than "width", the output is truncated. "VOPEN" MUST be called prior to using this function. EXAMPLES: vputf(message, 10); VPUTS VPUTS PROTOTYPE: vputs(char *string) ARGUMENTS: string - Pointer to character string RETURN VALUE: None DESCRIPTION: The "vputs" function outputs a character string to the IBM-PC video screen using the video library functions. "VOPEN" MUST be called prior to using this function. EXAMPLES: vputs(message); VTSTC VTSTC PROTOTYPE: int vtstc() ARGUMENTS: None RETURN VALUE: 0 - No key pressed 1-127 - ASCII value of key pressed < 0 - Special function key as defined in "video.h" DESCRIPTION: The "vtstc" function tests for a key pressed on the system console, and returns its value. A returned value of zero (0) indicates that no key was found to be pressed. Note that due to the buffering of the IBM-PC keyboard, every keypress will be reported, even if the VTSTC function is called after a key is pressed and released. EXAMPLES: if(vtstc() == 0x1B) /* exit loop on ESCAPE key */ break; VUPDATEXY VUPDATEXY PROTOTYPE: vupdatexy() ARGUMENTS: None RETURN VALUE: None DESCRIPTION: This function updates the real X/Y cursor position on the video screen to reflect the "logical" position where the next character will be output. The MICRO-C video library uses a BIOS interrupt (INT 10) to position the cursor, which is quite slow, compared to the speed of the library video routines. To prevent this from slowing down the video output, the cursor is only physically re-positioned when a "vgotoxy" or a "vgetc" is executed. This allows the library routines to run at full speed, and still put the cursor in the right place when output stops and an input request is made. A side effect of this is that the cursor on the screen will not appear to move unless you call "vgotoxy" or "vgetc". This only affects the physical cursor on the screen, MICRO-C maintains its own internal cursor location which it uses to determine where on the screen the next write will occur. Some applications which run in real time (Such as a terminal emulator) do not call "vgetc", but use "vtstc" to poll the keyboard on a regular basis. In this case, the "vupdatexy" routine should be called any time that the visual position of the cursor is important. "VOPEN" MUST be called prior to using this function. EXAMPLES: vupdatexy(); /* position the cursor * c = vtstc(); /* Test for a character */ MICRO-C TABLE OF CONTENTS Page 1. INTRODUCTION 1 1.1 Code Portability 2 1.2 Compiler Portability 2 1.3 The MCC command 3 2. THE MICRO-C PROGRAMMING LANGUAGE 4 2.1 Constants 4 2.2 Symbols 4 2.3 Arrays & Pointers 7 2.4 Functions 7 2.5 Control Statements 8 2.6 Expression Operators 10 2.7 Preprocessor Commands 12 2.8 Error Messages 13 2.9 Quirks 17 3. ADVANCED TOPICS 20 3.1 Conversion Rules 20 3.2 Assembly Language Interface 21 3.3 Compiling for ROM 24 4. PORTING THE COMPILER 25 4.1 The "io" module 26 4.2 The "code" module 28 4.3 The "compile" module 33 4.4 Porting without a compiler 34 4.5 Porting without a linker 34 4.6 Optimization Techniques 35 5. THE MICRO-C PREPROCESSOR 38 5.1 The MCP command 39 5.2 Preprocesor Commands 40 5.3 Error messages 43 6. THE MICRO-C OPTIMIZER 45 6.1 The MCO command 45 6.2 Porting to a new processor 46 7. THE COMMAND CO-ORDINATOR 47 7.1 The CC command 47 MICRO-C Table of Contents Page 7.2 Using multiple object modules 48 8. THE MAKE UTILITY 49 8.1 MAKEfiles 49 8.2 Directives 52 8.3 The MAKE command 53 8.4 The TOUCH command 54 9. THE SOURCE LINKER 55 9.1 The SLINK Command 55 9.2 The External Index File 56 9.3 Multiple source files 57 9.4 Source file information 57 9.5 The SINDEX utility 59 10. LIBRARY FUNCTIONS 60 10.1 Standard Library Functions 60 10.2 IBM-PC/MS-DOS Library Functions 61