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Modula-2 Compiler Version 1.1 (C) Copyright 1987 Fitted Software Tools. All rights reserved. Fitted Software Tools P.O.Box 956129 Duluth, Ga 30136 DISCLAIMER OF WARRANTY THIS SOFTWARE AND MANUAL ARE PROVIDED "AS IS" AND WITHOUT WARRANTIES AS TO PERFORMANCE OR MERCHANTABILITY. THIS SOFTWARE IS PROVIDED WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES WHATSOEVER. BECAUSE OF THE DIVERSITY OF CONDITIONS AND HARDWARE UNDER WHICH THIS SOFTWARE MAY BE USED, NO WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE IS OFFERED. THE USER IS ADVISED TO TEST THIS SOFTWARE THOROUGHLY BEFORE RELYING ON IT. THE USER MUST ASSUME THE ENTIRE RISK OF USING THIS SOFTWARE. IBM is a registered trademark of International Business Machines Corporation. Introduction 2 Chapter 1 Introduction Thank you for your interest in our Modula-2 compiler. This system features a Modula-2 compiler with an integrated editor and "make" facility, a program linker, a makefile generator, and an execution profiler. The compiler generates code for the Intel 8086 "huge" or "large" memory model: In the "huge" memory model, each module has its own data and code segment, each of which can be up to 64k in size; In the "large" memory model, all the modules' static data is combined into a single data segment. In either model, pointers are 4 bytes long and all the leftover memory is available for the "heap". More restrictive memory models are not currently supported. All the library and runtime support source code is provided to our registered users (see Shareware). We hope that our effort will prove itself worthy of your support. Introduction 3 1.1 Hardware requirements This system will run on IBM PC, PC/AT, or compatible systems with at least 512K of RAM, two double sided floppy disk drives and a monochrome display adapter, color graphics adapter or equivalent. For best performance, a hard disk and 640K of RAM are recommended. 1.2 Software requirements This system will run under DOS version 2.0 or later. No other software is required to use this system, but you will need an assembler if you intend to modify one of the runtime support modules: M2Reals (floating point support), M2Longs (LONG arithmetic) or M2Procs (coroutine handling). 1.3 What is new in version 1.1 The compiler now allows the specification of module priorities in the module header. As an example on the use this new capability, we include the source code of a simple multitasking communications program running under a small kernel that supports interrupt processes, signals and locks. The compiler and linker now allow you to use a "large" memory model. In this memory model, all the modules share a common data segment for static data; pointers are still 4 bytes long. Using the large memory model usually produces smaller (and faster, although you may not be able to tell) executable files, as data references to external objects do not cost anything extra. The compiler has new command line options, so that you can directly invoke the editor or the make process from the command line. From the compiler menu you may now invoke the linker and the makefile generator, although these are still freestanding programs. The compiler now accepts EXPORT statements in definition modules, but simply treats them as comments. This capability was requested by some Introduction 4 of our users. The editor includes 3 new commands: delete line, delete to end of line and delete word. M2ED.CFG now has additional information in it: through EDCONFIG you may now select the display attributes (colors) to be used by the editor; you may also select different default values for tab spacing and whether or not to expand tabs. A new option was added to M2Link: /SWAP. When invoked, this option directs the linker to swap the code segments of the program being processed out to disk, thereby allowing you to link larger programs. Many new library modules were added: Keyboard, display, DOS file and directory handling, and even modules to handle windows and pop up and pull down menus. These libraries are provided just to help you get started; We will leave the production of more elaborate libraries to those vendors that specialize in such. 1.4 As version 1.0 becomes history... Before going on, we would like to thank all our registered users: your encouragement made this new version possible. We will strive to never let you down. We also appreciated the input received from those that evaluated the product and were nice enough to let us in on their thoughts. Software installation 5 Chapter 2 Software installation Before starting, please print the file READ.ME, which provides a description of every file in the distribution disks. 2.1 Theory The library module TermIO (through which Terminal does its IO) requires that the ANSI.SYS driver be installed. The executable files (MC.EXE, M2LINK.EXE, ...) should, for ease of operation, be placed in a drive/directory named in the DOS PATH variable. The editor configuration file M2ED.CFG must be accessible through the DOS PATH variable. Both the compiler and the linker will use the environment variable M2LIB to locate required library modules (the format for the M2LIB entry matches that of the DOS PATH). The environment variable M2MODEL may be set to 'HUGE' or 'LARGE', after which you no longer have to tell the compiler what memory model to compile for (unless you wish to override the environment selection). IF M2MODEL is not set, the compiler, by default (and for compatibility with version 1.0), assumes that you want to compile for the HUGE model. The compiler and utilities in this package do not keep many files open simultaneously. If you set the FILES parameter in CONFIG.SYS to 10 you should not encounter any problems. For performance considerations, you should also allocate more than the default number of buffers for DOS: If you are running on a PC class machine, try allocating 20 buffers in your CONFIG.SYS. On an AT type machine, try 64 buffers. Example CONFIG.SYS: DEVICE=ANSI.SYS FILES=10 BUFFERS=20 Software installation 6 This compiler is a memory hog (you heard it here first!). Therefore, unless you have 640k of memory installed in your system, you should have COMMAND.COM available for reload once you exit the compiler. If you have 640k of memory, you will probably want to enable the "COMMAND save" feature of the compiler, which will stop it from clobbering the resident portion of COMMAND.COM. Just add the following line to your AUTOEXEC.BAT file: SET CMDSIZE=NN where NN is the size of the resident portion of COMMAND.COM in K (18 for DOS 3.0). MC clobbers the top of the memory space available for use during initialization. Therefore, to find out the size of the resident portion of COMMAND.COM try the following procedure: start by setting CMDSIZE to the size of COMMAND.COM. If now you execute MC, exit it, and press the F3 key, DOS will still remember your MC command. Decrement CMDSIZE and retry the MC test until the system forgets your last command (COMMAND.COM had to be reloaded). Because the compiler supports 2 different memory models, 2 different sets of library object files (.M2O) are provided, one for each of the memory models. If you are going to be using both memory models, keep each of these sets of files on a different directory, and change the M2LIB path according to the model in use. We use the following BAT files to take care of this: LARGE.BAT: set M2MODEL=LARGE set M2LIB=C:\M2\LIB;C:\M2\LIBL HUGE.BAT: set M2MODEL=HUGE set M2LIB=C:\M2\LIB;C:\M2\LIBH where \M2\LIB is the directory where all the DEF files reside, \M2\LIBL contains the LARGE memory model M2O files,... In the following discussion we will, for simplicity sake, assume that you will be using only one of the memory models. 2.2 Recommended setup for a system with 2 floppy drives This whole system is too large to fit in a single 360k floppy. Therefore, it is recommended that you build a "compiler" floppy and a "utilities" floppy (you may combine them both in a 720k or 1.2Mb floppy). Software installation 7 On the compiler floppy, place the compiler (MC.EXE), all the library definition modules (*.DEF), the file M2ED.CFG and DOS' COMMAND.COM. The utilities floppy will take the rest of the system: the linker (M2LINK.EXE), other .EXE files, and the library and runtime support object files (*.M2O and *.BIN). Assuming that you will use drive A for the compiler and utilities disk and drive B as your work drive, add the following to your AUTOEXEC.BAT file: SET PATH=A: SET M2LIB=A: If you follow these suggestions, you may use all the system's capabilities. Just remember to swap the floppy in drive A before and after invoking the linker from the compiler's menu. 2.3 Recommended setup for a hard disk system Place the executable files (*.EXE) and M2ED.CFG in a directory currently in the DOS search path, or in a new directory (ex: \MODULA2) to be added to the PATH list. Example: SET PATH=C:\BIN;C:\MODULA2 Make a directory for the library files (ex: \M2LIB) and copy all the .DEF, .M2O and .BIN files to it. To the AUTOEXEC.BAT file add the line: SET M2LIB=C:\M2LIB You will probably want to create a directory for your own reusable library modules. This directory can be added to the M2LIB environment variable. Example: SET M2LIB=C:\M2LIB;C:\MYLIB You may keep your projects in their own, individual, directories. A little tour through the system 8 Chapter 3 A little tour through the system After you finish the installation as described above, please copy the files identified as the "system tour files" in the READ.ME file to your work disk or directory. Because we do not know your particular system configuration, in the following examples we will assume the worst possible scenario. Therefore, some of the capabilities of this system will not be fully exploited. Specifically, we will not invoke the linker or run the programs from the compiler menu, neither will we invoke a DOS shell to run DBG2MAP. 3.1 The tour First, we will look at the unnatural case of compiling, linking and running a program that works the first time around. Please execute the following commands: MC SIEVE /C M2LINK SIEVE /O Well, that's it! Ready to run... SIEVE Now for the more usual case: MC BADSIEVE From the compiler menu, select 'C' for compile. Gee, that was quick! Press RETURN to take a look at our errors... The cursor is now positioned at the location of the first error. Using the keys Ctrl-E (find next error) and Ctrl-P (find previous error) you may visit all the errors flagged by the compiler. All the while, the editor shows the error description on the top line of the screen. But, going back to the first error... We really confused the compiler when we mistakenly typed in '.' A little tour through the system 9 instead of '..' in the range declaration. Move the cursor back (left arrow key) to where the '.' is, type in another '.', and that should fix that! As you will see as you type Ctrl-E, that single error caused the compiler to dislike a few other things on that same line; we will just ignore those errors and go on. Go on to the next error location (line 22). This time, we should have used a ']' but typed '}' instead. The backspace key will delete the offending character; now, type the ']' in its place. And that is that. Shall we try to compile the program again? Press Alt-S to save the file, Alt-Q to leave the editor and, back at the main menu, select 'C'. More errors?! These errors should have been detected during pass2 of the compiler; If not, you may try to fix these errors and recompile, or you may opt for loading and compiling the new file BADSIEV1.MOD, which contains the earlier fixes. Going back to the editor... We find that we used the identifier 'cnt' which is undefined; we really meant to use count. So, moving the cursor around with the cursor keys and/or deleting characters with the backspace or delete key, please replace 'cnt' by 'count'. Searching for the next error... The next error occured during the processing of the call to WriteCard. What happened here is that WriteCard requires 2 parameters, the second one being the size of the field to display. So, to fix it, let's insert a comma after 'count' and some number (for example 'count,4'). Any more erors? No, that is it... We now save the file (Alt-S), quit the editor (Alt-Q) and recompile (c). Now, the program should have compiled without errors. If not, you may recompile BADSIEV2.MOD instead. We may now quit the compiler (q). By now, we have some program that has compiled clean (BADSIEVE, BADSIEV1 or BADSIEV2). In what follows, we will assume all went well and we have BADSIEVE. If you look at the directory, you will see the new object module created as a result of the previous exercise (BADSIEVE.M2O). The compiler always writes its output to a file with the extension 'M2O'. Let us link and test the program: M2LINK BADSIEVE /L A little tour through the system 10 We use the /L option so that the line number information written out by the compiler to the object file will be preserved by the linker. We will need this information later. BADSIEVE A runtime error? And it gives us a PC location. Very informative, is it not? How in the world are we supposed to fix the program based on that? Do not dispair! Looking at your directory, you will notice that the linker created 2 files: BADSIEVE.EXE and BADSIEVE.DBG. No, TYPEing BADSIEVE.DBG does not help, it just displays garbage. But we have a utility called DBG2MAP that will convert the information in that file to a DOS LINK compatible MAP file. Let's try it: DBG2MAP BADSIEVE Now, using your favorite editor (or the editor in MC: MC BADSIEVE.MAP and then E), look at the contents of BADSIEVE.MAP. In the last few lines of the file, we have the line number information for BADSIEVE. If you look up the line whose address is closest (but lower) to the PC in the error message, you get the number of the line where the error occured (line 22). Let's see what happened... MC BADSIEVE Pick 'E' to go into the editor and, either move the cursor down to the line indicated by your research, or let the editor find it with Alt-G. So, what is the problem? Well, we declared the 'flag' array to have a maximum index of 8190, but 'j' got bigger than that (the FOR loop will increment 'j' up to the value of 10000). You may fix the problem by deleting the '10000' and typing in its place 'SIZE'. Recompile the program, link it, and run it. Did it work? Good. It is time for you to experiment on your own. But, before you do much more, you may want to check out the Editor chapter of the documentation. The Compiler 11 Chapter 4 The Compiler In Modula-2, identifiers may be used before they are declared, except when they are used in another declaration (this restriction does not apply to pointers). This forces the compilation process to be done in at least two passes. To avoid imposing unnecessary restrictions and, yet, provide reasonable performance, the two pass approach was selected: During the first pass, syntax analysis and declaration analysis are performed; The second pass performs the semantic analysis and code generation. The compiler has an integrated text editor. Should errors be encountered, the editor is invoked at the end of the current compiler pass (sooner, if an error is found during the processing of an import list or if 20 errors are identified). The compiler also has a built in "make" processor. A makefile must be created before this process is invoked. Although you can create a makefile using the editor, we recommend that you use the utility provided for that purpose: GENMAKE (this utility may be invoked from the compiler menu -- G). The Compiler 12 4.1 Running the compiler Compiler invocation: MC [workModule] [/p mainModule] [/c] [/e] [/m] The '/p' option may be used to indicate the name of the main module of the program that you are working on (the name should not have an extension). If this option is not used, but workModule is entered without an extension, then the same name is also used for mainModule. If you use of the '/c' command line option, the compiler starts compiling "workModule" immediately and, if no errors are encountered, will bring you right back to the DOS prompt. This is useful when running the compiler from a batch file: MC myprog /c The '/e' option will send you straight into the editor. The '/m' option invokes the make processor, which will look for the file mainModule.MAK for the dependencies list. The compiler always sets the DOS errorlevel to 0 if the last compile was successful (no errors); otherwise, the DOS errorlevel is set to 1. If the compiler is invoked without the '/c', '/e' or '/m' options, you will get a screen that looks something like this: Modula-2 compiler, Version 1.1 (C) Copyright 1987 Fitted Software Tools. All rights reserved. Memory model in use: LARGE Heap in use: 0K Available Heap: 229K Program: sieve Work module: sieve.MOD Program New Options DOS Quit Compile Edit Genmake Make Link eXecute > The options at this point are: Program Specify the name of the main program module. New Specify another "Work module". The Compiler 13 Options To select the memory model to use. DOS Invoke a new DOS shell. At the DOS prompt, you should type EXIT to return to this system. Quit Return to DOS. Compile Compile the "Work module". Edit Edit the "Work module". Genmake Invoke the GenMake program, passing as argument the name in Program. Make Recompile all the necessary modules as per the rules of a makefile (The makefile is assumed to have the name in Program and the extension of .MAK). Note: If errors are encountered during the compilation of one of the modules, the make process is aborted. After fixing the errors, select Make again. Link Invokes the linker (M2Link) passing along as arguments the name in Program and '/L'. eXecute Program is executed. 4.2 The compilation process 4.2.0.1 The input file If the module to be compiled is already loaded into one of the editor buffers, that source is compiled. Otherwise, the compiler tries to open the named file. 4.2.0.2 The imported modules The compiler and the linker cooperate in assuring that all the modules that refer to a particular definition module will have been compiled against the same version of that definition module. To this end, the compiler places in the 'module header' and 'module import' records of the object file a "module key". This module key is the date of the DEF file used during the compilation of the implementation module or during the processing of the IMPORT The Compiler 14 statement. Due to this, the compiler will not look in the editor buffers for the DEF files needed to process an IMPORT list. These are always read in from the disk. 4.2.0.3 The output file The output from the compilation of a main module or an implementation module is a single output file, with the same name of the source file but with the extension of 'M2O' (Modula-2 Object). The compilation of a definition module does not generate any new output files. If the compilation is successful (no errors), the compiler simply 'touches' the source file, updating its modification time. 4.2.0.4 A warning Because of the fact that the compiler uses the date of the DEF file as that module's key, you may not modify a DEF file unless you intend to recompile all the modules that use it, nor can you copy the file in such a way that its date is not preserved. In particular, if you are going to be transferring your modules between computers, you must use some procedure that will preserve all the DEF files' dates. 4.3 Compiler directives Certain compiler code generation options may be set through directives included in the program text. These directives must appear immediately at the beginning of a comment; multiple directives may be entered in a single comment by separating them by commas. Example (* $S-, $R+ *) A '+' sets the directive to TRUE, a '-' sets it to FALSE. The following compiler directives are defined: $A Alignment. Default $A+. If enabled, all new variables declared are aligned on a word boundary. Record fields are packed (not aligned) regardless of the setting of this option. The Compiler 15 $S Stack overflow checking. Default $S+. If enabled, stack overflow checking is performed on entry to a procedure and when copying open arrays to a procedure's local stack frame. $R Range checking. Default $R+. If enabled, before any assignment is made to a variable of a subrange type, the value to be assigned is tested against the limits of the subrange type. $T Array subscript checking. Default $T+. If enabled, any time a subscript operation is performed on an array, the subscript value is checked to confirm that the operation would not generate an address outside the bounds of the array. $L Generate line number information. Default $L-. If this option is enabled, the compiler will include a list of source code line numbers and their corresponding object code offsets in the output file. This line number information is passed on to the .DBG file when the program is linked with the /L option. 4.4 Runtime errors When, during the execution of a program, a runtime error is detected, the runtime error handler will terminate the program and write out a message indicating the type of error encountered and its location (PC address). To find the location of the error in the source code, run DBG2MAP against the .DBG file generated by M2LINK for this program. Scanning the .MAP file created, you should be able to always determine the module and procedure where the error occured. If the $L+ directive was used when compiling the module in question and the /L option was used when linking the program, the error location can be pinpointed to the offending line by scanning the line number information at the end of the .MAP file. 4.4.1 Trapping runtime errors in your program The Library module System provides you with a means of intercepting runtime errors. The following are the currently defined runtime error numbers that may be passed to your error handler routine: 0 stack overflow ($S option) The Compiler 16 1 range error ($R or $T option) 2 integer/cardinal overflow (divide by zero) 3 floating point error 4 function did not execute a RETURN 5 HALT was invoked 4.5 Compiler size limits The following are the code and data size limits imposed by this compiler: - A string constant cannot exceed 80 characters. This is also the limit set for the size of any identifier. - When using the HUGE memory model, each compilation module is assigned its own data segment, which can be up to 64k in size. In the data segment, the compiler allocates the space for all the module's global variables and some of the module's constants. - When using the LARGE memory model, all the modules' data are combined, at link time, into a single data segment (64k maximum). - The maximum size of a data structure is 65532 bytes. - The maximum amount of space allocated for variables local to a procedure is 32000 bytes. - The compiler will also refuse to generate the code to pass, in a procedure call, by value, a parameter greater than 65000 bytes in size. The following are the compiler's internal limits: - The maximum number of different (namewise) identifiers that can be processed in a single compilation is 2000. - The total number of characters in all the different (namewise) identifiers processed cannot exceed 12000 characters. - No single procedure can be translated into more than 10k of object code. - An array of 8k bytes is used to keep track of all the initialized data for a module. This imposes a limit on the total amount of string, real and long constants used in the compilation module. 4.6 The language supported The Compiler 17 This release of the compiler will translate a program written in the Modula-2 language as defined by Niklaus Wirth in the 3rd edition of his book "Programming in Modula-2", with the exceptions noted bellow: - Integer and Cardinal arithmetic overflow is not detected. - ASM is a reserved word in this implementation. - For those programmers that "grew up" in the Hex world, a way to define CHAR literals in Hex is provided: 20X corresponds to the "space" character in ASCII. 4.6.1 LONGINT and LONGCARD This compiler implements the standard types LONGINT and LONGCARD. Operands of the type LONGINT or LONGCARD may appear in any expression, just like INTEGER or CARDINAL. But that is about it! Subranges of these types are not supported. No standard procedure (like INC, DEC) except the ones listed later in this document will accept operands of one of these types. A variable of type LONGINT or LONGCARD cannot be used as the control variable in a FOR loop. Neither can CASE labels be of a LONG type. Constants of type LONGINT or LONGCARD can be coded in decimal only and are terminated by an 'L'. Example 123L is a valid LONGCARD or LONGINT constant -348762L is a valid LONGINT constant 565656 -89076 are CARDINAL and INTEGER constants out of range 4.6.2 Additional standard procedures 4.6.2.1 NEW and DISPOSE NEW and DISPOSE have been deleted from the language definition in the 3rd edition of Wirth's book. We implement them thus: NEW(p) Invokes the procedure ALLOCATE, which must conform to the type: PROCEDURE ( VAR ADDRESS, CARDINAL ) passing along p and the size of the object p is defined as pointing The Compiler 18 to. DISPOSE(p) Invokes the procedure DEALLOCATE, which must conform to the type: PROCEDURE ( VAR ADDRESS, CARDINAL ) passing along p and the size of the object p is defined as pointing to. The procedures ALLOCATE and DISPOSE must, therefore, be defined in the module using NEW and/or DISPOSE, or imported from some other module, like Storage. 4.6.2.2 LONG and SHORT PROCEDURE LONG( INTEGER ) :LONGINT; PROCEDURE LONG( CARDINAL ) :LONGCARD; PROCEDURE SHORT( LONGINT ) :INTEGER; PROCEDURE SHORT( LONGCARD ) :CARDINAL; LONG takes an INTEGER (CARDINAL) and converts it into a LONGINT (LONGCARD). SHORT takes a LONGINT (LONGCARD) and converts it into an INTEGER (CARDINAL). 4.7 Objects exported by the pseudo module SYSTEM 4.7.0.1 TYPE BYTE Takes 1 byte of storage. Only assignment is defined for this type. If the formal parameter of a procedure is of type BYTE, the corresponding actual parameter may be of any type that takes 1 byte of storage. If the formal parameter of a procedure is of type ARRAY OF BYTE, the corresponding actual parameter may be of any type. 4.7.0.2 TYPE WORD Takes 1 word (2 bytes) of storage. Only assignment is defined for this type. If the formal parameter of a procedure is of type WORD, the corresponding actual parameter may be of any type that takes 1 word of storage. The Compiler 19 If the formal parameter of a procedure is of type ARRAY OF WORD, the corresponding actual parameter may be of any type. Care should be taken in this case, as the size of the parameter passed is rounded up to an even size. 4.7.0.3 TYPE ADDRESS The type ADDRESS is compatible with all pointer types. ADDRESS itself is defined as a POINTER TO WORD. In this implementation, the type ADDRESS is not compatible with any arithmetic type. This is due to the fact that the Intel 8086 series processors use segmented addresses. It would not be hard to implement automatic conversions between LONGCARD and ADDRESS but it is felt that this would be contrary to the spirit of the language, whereby the compiler is not expected to perform any "magic" tricks. Instead, two functions are provided for that purpose: FLAT and PTR. 4.7.0.4 SEG and OFS These are field definitions for POINTER types. If you import these you may access the segment or offset portions of a pointer variable using regular field selection syntax. Example pointer.SEG :segment portion of pointer 4.7.0.5 PROCEDURE ADR ADR( designator ) Returns the address of designator (type ADDRESS). 4.7.0.6 PROCEDURE FLAT FLAT( ADDRESS ) returns a LONGCARD "flat" address. 4.7.0.7 PROCEDURE PTR PTR( LONGCARD ) returns an ADDRESS corresponding to the "flat" address represented by the LONGCARD. 4.7.0.8 PROCEDURE SEGMENT SEGMENT( designator ) returns the segment portion of the address of 'designator'. Example: DX := SEGMENT( buffer ); would assign to DX the segment value of ADR(buffer). 4.7.0.9 PROCEDURE OFFSET OFFSET( designator ) returns the offset portion of the address of The Compiler 20 'designator'. 4.7.0.10 PROCEDURE NEWPROCESS NEWPROCESS(p:PROC; a:ADDRESS; n:CARDINAL; VAR p1:ADDRESS) creates a new process whose entry point is p and workspace is at a for n bytes. p1 is the new process pointer. This process is not activated until a TRANSFER to p1 is done. The starting priority of the new process is the current processor priority at the time NEWPROCESS is invoked (please refer to the section on Module Priorities). 4.7.0.11 PROCEDURE TRANSFER TRANSFER( VAR p1, p2 :ADDRESS) suspends the current process, assigning it to p1 and resumes p2. The current process' value is assigned to p1 only after p2 has been identified; it is, therefore, okay for p1 and p2 to be the same. The process is resumed at the same priority level that it was running at, at the time of suspension. 4.7.0.12 PROCEDURE IOTRANSFER IOTRANSFER( VAR p1, p2 :ADDRESS; intVector :CARDINAL ) issues a TRANSFER from p1 to p2 (just the way TRANSFER does it) after installing the current process for reactivation when an interrupt comes in through interrupt vector intVector. When the interrupt occurs, the interrupt vector is reloaded with its previous value. A TRANSFER is done to the I/O process (the one that issued the IOTRANSFER) such that p2 now contains the value of the process that was running when the interrupt occured. 4.7.0.13 ASSEMBLER An 8086 inline assembler is provided. Once ASSEMBLER is imported from SYSTEM, you can enter inline assembler code by bracketing it with the keywords ASM and END. Assembler input is free form. Comments are entered as in regular Modula-2. Example loop: CMP BYTE [SI], 0 (*end of string?*) MOV BYTE [DI], [SI] INC SI INC DI (*increment pointers*) JMP loop The assembler accepts all the 8086/8088 opcode mnemonics. Address The Compiler 21 operands can be coded in just about any form acceptable to other assemblers, except that the only operator supported if '+'. Operand type overrides are: WORD, BYTE, FAR, NEAR and are not to be followed by the keyword POINTER or PTR. Example label: MOV AX, ES:[BX,DI+5] MOV AX, ES:5[DI+BX] MOV WORD [5], 1 CALL NEAR [DI] TEST BYTE i+2, 1 All the mnemonics and register names must be entered in upper case. In case you need to use a Modula-2 name that conflicts with one of the assembler reserved symbols, you may precede it with a '@'. Example MOV @AX, AX would generate a move from register AX to variable AX. All modula-2 variables can generaly be accessed in assembler. Record field names are not accessible from assembler. The assembler will not automatically do anything for you. For example: if you specify a VAR parameter as an operand to an instruction, you are naming the address of the pointer to the actual parameter. Example PROCEDURE p( VAR done :BOOLEAN ); ... ASM LES DI, done MOV BYTE ES:[DI], TRUE END; is the correct way of storing TRUE in done. The following types of constants may be accessed in assembler: INTEGER, CARDINAL, BOOLEAN, CHAR and enumeration constants. All labels declared inside an ASM section are local to that section of code. But labels names cannot match some name known in the scope of the current procedure. Labels can only be referenced in jump instructions. All jumps are optimized by the compiler. There is, therefore, no need (or capability) to specify the size of a jump. In particular, the compiler will turn a conditional jump out of range into a reverse conditional jump over a far jump to the original destination. Remember, this is a Modula-2 compiler, not an assembler! The inline assembler capability is provided for use in exceptional situations only. 4.8 The generated object code The Compiler 22 4.8.1 Data type representation CHAR 1 byte INTEGER 2 bytes 2's complement CARDINAL 2 bytes LONGCARD 4 bytes LONGINT 4 bytes 2's complement BOOLEAN 1 byte (1=TRUE, 0=FALSE) REAL 4 bytes Intel 8087 format. BITSET 1 word. 0 is low order bit, 15 is high order bit. Enumerations 1 byte SETs 1 to 8 words (sets of up to 256 elements) POINTERs 4 bytes in Intel 8086/88 format PROCEDUREs 4 bytes POINTER to procedure entry point Addresses are represented in the default Intel 8086 format: 1 word byte offset 1 word segment Numeric values are likewise represented the way the Intel 8086 processor family likes them: low order byte first, high order byte last. 4.8.2 The runtime memory map Currently, the compiler generates code using the "large" or "huge" memory model only. In the "huge" memory model, each module has its own data and code segments. In the "large" memory model, each module has its own code segment. The entire program has one data segment. The linker binds all the code segments first, and then all the data segments. The stack is allocated above the data segments. All the The Compiler 23 remainning memory is available for the heap. When a program is loaded for execution, here is what the memory looks like: From low to high addresses: 0 ---------------------------------------------- I Interrupt vectors I I DOS I PSP I Program segment prefix I PSP+100h I Program Code segments I I Program Data segment(s) I StackSeg I Stack I HeapTop I Heap I I ... I I DOS Command (resident portion) I MemTop ---------------------------------------------- Label names on the left are the ones exported by System. This system uses interrupt vector 192 (0C0H) at location 0000:0300. Interrupt 192 is issued by a program when a runtime error occurs, when HALT is invoked or when a coroutine other than the main one terminates via a return. The first word (offset 0) in every code segment contains the data segment value for that particular module (for the program, in the case of the "large" memory model. 4.8.3 Procedure calling conventions Procedure parameters are pushed into the stack 1st argument first. Control is then transferred to the procedure through a FAR call. It is the called procedure's responsibility to remove its parameters from the stack before returning. 4.8.3.1 Parameter passing (all except open array parameters) If the formal parameter of a procedure is a value parameter, the actual parameter is copied into the stack. If the formal parameter is a variable parameter (VAR), the address of the actual parameter is pushed into the stack (first the segment portion of the address and then the offset part). 4.8.3.2 Parameter passing (open array parameters) If the formal parameter is an open array, the address and HIGH value The Compiler 24 of the corresponding formal parameter are pushed into the stack (HIGH value first, and then the address, as above). If the open array parameter is a value parameter, the value of the actual parameter is copied into the stack on procedure entry. 4.8.3.3 Returning values from a function procedure One byte results are returned in AL, two byte results are returned in AX, and four byte results are returned in DX:AX (DX has the high order part of the result). 4.9 Module priorities Eight module priority levels are supported in this implementation, from 0 (highest priority) to 7. Priorities are implemented by masking off, on the 8259 interrupt controller, all the interrupts at or below the current priority level. Because the PC usually runs with several of the interrupt levels disabled, it is not easy to decide what the interrupt mask for the value for "no priority" should be for your particular application. The implementation of NEWPROCESS, therefore, assumes that you have enabled all the interrupts that your program will be capable of processing before you create your processes. The value in the interrupt mask register of the 8259 at the time of process creation will determine the initial priority level of this process, once it gets started. Because of this, invoking NEWPROCESS from inside a priority module is usually not what you want to do! Execution priorities are changed when entering/exitting procedures in modules that have a priority specification, and during the execution of some form of a TRANSFER. We highly recommend that you study the communications program provided, paying particular attention to the module Kernel, for an example of how to use priorities with this system. NOTE: The compiler does not restrict the priority level specified (any number will do). You must, therefore, exercise care in defining a module's priority level. On the other hand, it is easy to add additional priority levels by simply modifying the runtime module M2Procs. The Compiler 25 4.10 Memory models In general, you may compile the same code under either the LARGE or the HUGE memory model. The only factor to consider is when using inline assembler. Under the HUGE memory model, the compiler generates code to reload DS after any invocation of an imported procedure or a VARiable procedure. Under the LARGE memory model, this is not necessary as a single data segment is defined. If you write some inline assembler code that modifies DS, please restore it, even if the next thing you do is a RETurn; this way, your routine will work regardless of whether you use the LARGE or the HUGE memory model. Under the HUGE memory model, access to external variables is done through an indirect pointer, whereas in the LARGE memory model the external variable resides in the programs ONLY data segment and is, therefore directly accessible. The Text Editor 26 Chapter 5 The Text Editor The text editor included in this package has all the features that you have come to expect from a basic program editor: the ability to insert, delete, move, find and replace text; support for concurrent editing of multiple files (as many as will fit in memory) in separate windows (as many as will fit on the screen) with the ability to copy or move text from window to window. Although you may load the same file in two different windows, the editor will not be aware of the fact and will treat the two copies as two different files. The only preset limitation in the editor is that it cannot handle files bigger than 64k. This decision was justified by the fact that Modula-2 programs are supposed to be modular. File load/save speed was the overriding factor here. All the text editor keys are defined by the user through the use of the EDCONFIG program. When the editor starts, it expects to find the file M2ED.CFG in the current PATH. M2ED.CFG will also tell the editor what display colors (attributes) to use for the Status line, for Normal text and for Marked text blocks. Finally, M2ED.CFG also contains the default settings for the TAB size value, as well as whether or not the editor will expand the tabs inserted into the text spaces. Note: Tabs present in a file will not be expanded to spaces by the editor. To get you started, we provide a M2ED.CFG file with the following definitions: Cursor left : Left Cursor right : Right Cursor up : Up Cursor down : Down Previous word : ^Left Next word : ^Righ Page up : PgUp Page down : PgDn Cursor to beginning of line : Home Cursor to end of line : End Cursor to top of window : ^Home Cursor to bottom of window : ^End To beginning of file : ^PgUp To end of file : ^PgDn The Text Editor 27 Current line to top of window : AltT Toggle insert/overtype : Ins Delete character under cursor : Del Delete previous character : ^H Delete Current Line : ^Y Delete to EOL : AltY Delete Word : ^D New file : AltN Read file : AltR Write block : AltW Save file : AltS Open window : ^O Close Window : ^C Next window : F2 Previous window : aF2 Split screen : ^S Mark beginning of block : F7 Mark end of block : F8 Goto beginning of block : AltB Goto end of block : AltE Clear block marks : AltH Copy block : AltC Delete block : AltD Move block : AltM Search forward : F5 Search backwards : aF5 Replace forward : F6 Replace backwards : aF6 Global replace : ^F6 Repeat last search/replace : F1 Goto next error : ^E Goto previous error : ^P Goto line : AltG Set options : AltO Redraw the screen : ^L Quit : AltQ The Linker 28 Chapter 6 The Linker The linker is invoked by the command line M2LINK myprog [/s n] [/h n] [/o] [/p] [/l] [/swap [path]] where 'myprog' is the main module of the program you are creating. The options are thus: /s n n is the size of the stack to allocate (default is 4096). /h n n is the amount of space to reserve for the heap (in paragraphs). The default is all the free memory. /o invokes the optimizer. The optimizer prevents the output, to the object file, of all the procedures that are part of included modules but are not referenced. This will make your final EXE files smaller. /p tells the linker to include the profiler (M2Prof.M2O). For further information, see the chapter on "Utilities". /l tells the linker to process the line number information in the .M2O files and include it in the .DBG file. This option is disabled if the optimizer is invoked. /k tells the linker to ignore module keys, i.e. to not check for module version compatibility. This option should be used with extreme care. /swap [path] tells the linker to use a swap file. Code segments will be kept in this swap file instead of in main memory during the link process. This allows you to link larger programs. The linker creates two files: the .EXE file is your executable program, the .DBG file is a file containning symbol information for use by other utilities (see Map file generator, Profiler). If the /swap directive is used, a swap file is created. You may select the path (drive:directory) where the swap file is to be created. Example: The Linker 29 M2LINK myprog /swap D: 6.1 Module keys The module header record and the import records written out by the compiler to the object file are stamped with the date of the .DEF file that was processed - this becomes the module key. The linker will assure that these module keys in the module header of the imported module and in the import record match; If they do not match, both modules were not compiled using the same definition module. Because of the use of module keys, it is imperative that the date of the distributed .DEF files not be modified unless you intend to recompile the implementation modules. Other utilities 30 Chapter 7 Other utilities 7.1 Editor configurator This program lets you define the keystrokes to be used to invoke all the editor commands, the screen attributes (colors) to use, and the default editor options. Invokation: EDCONFIG EdConfig presents you with a menu from which you may elect to modify the default editor options, the display attributes, or configure the editor commands. If you are creating a new configuration file, you must configure the editor commands. If you chose to configure the editor commands, you will be prompted for a log file (default M2ED.HLP), a text file in which all of your command choices will be saved. You may print this file to create a quick reference card. EDCONFIG will then prompt you for the key sequence to be used for each editor command. For each command, EDCONFIG will also give you the option of defining an alternate key sequence. When you select Quit, the program will prompt you for an output file, the default being 'M2ED.CFG'. 7.2 Map file generator Invokation: DBG2MAP program_name Other utilities 31 Reads the .DBG file created by M2LINK and creates a DOS LINK compatible .MAP file. 7.3 Make and the Makefile generator These utilities eliminate the burden, on the user's part, of having to figure out which modules are affected and, therefore, need to be recompiled as a result of any changes to particular definition modules. GENMAKE creates the .MAK file, the file with all the dependencies (this is the hard part) whereas MAKE (built into the compiler) will insure that these dependencies are observed when updating the object files. GENMAKE Invokation: GENMAKE main_module_name generates the .MAK file containning all the module dependencies for the named program. It does this by reading all the IMPORT statements in the main module and, recursively, generating the dependency lists for all those modules (but only the ones that can be found in the current directory!). GENMAKE will indeed read all the .MOD and .DEF files involved. MAKE invocation: see "Running the Compiler". MAKE will invoke the compiler as needed to assure that all the dependencies in the make file are observed. MAKE is dumb in that it will just run through the makefile sequentially. It was GENMAKE's responsibility to see that the dependencies are listed in a proper sequence. Please keep this in mind if you should edit a makefile! 7.4 The execution profiler When you link your program with the /p option, the module M2Prof is included in the output generated. When you execute the program, the profiler will ask you for the name of the .DBG file to use and give you an option of profiling your entire program (generating an execution profile by module), a particular module (generating an execution profile by procedure in that module) or a particular procedure (generating an execution Other utilities 32 profile by line in the procedure). Upon program termination, the profiler outputs the list of all the modules/procedures/lines profiled, ranked by execution time, to a file of your choice. This profiler is not that versatile, but it is useful nevertheless. It proved instrumental in pinpointing some obvious areas for improvement in the compiler (Oh, we did not tell you, did we? This compiler was written in the language it compiles -- Modula-2 -- and this system was used as our primary development tool since very early in the development process). The Library Modules 33 Chapter 8 The Library Modules For complete information on what each library module provides, as well as its proper usage, please refer to the .DEF files. In addition, the source code of all the library modules is available to all the registered users (see the order form in the back of this document for details). 8.1 Release 1.1 libraries In this release, several library modules were "extended". We have not created any source level incompatibility with the old library modules, that we are aware of. But you will have to recompile all your programs, as they will not link with the new library modules. Because of the implementation of module priorities, the new M2PROCS runtime support module has additional routines and different interfaces for the old ones. Shareware 34 Chapter 9 Shareware This software package is distributed as Shareware. Shareware distribution gives users a chance to try this software before buying it. Besides, by using this distribution method, we eliminate the high cost of publishing and advertising (our users do it for us) and can, therefore, provide the same product for less. If you try this program and continue to use it, you are expected to register it. This software can be freely distributed, as long as no money is charged for it, all the files are included, unmodified, and with their modification dates preserved. If you are going to place this software on a bulletin board (we thank you for it), please upload it in a library format (we suggest ARC) that will preserve this package's integrity. This software cannot be distributed as a part of, or in conjunction with, another product. This software cannot be used in a commercial environment without the payment of a $25 (as of this writing) license fee per copy. Our success will depend not only on the quality of this software but on the willingness of every individual user to "support" its developers. If you use this product, please send in the registration form in the back of this document, along with your registration fee. For $35 (as of this writing) we will send you the latest version of this software and all the library and runtime support source code (what a bargain!). This source code is made available to registered users only! Whether or not you use this product, please give complete copies of this software to others (the more the better). You are an integral part of our distribution channel! License terms 35 Chapter 10 License terms Before you register this product and become a licensed user, you are granted a limitted license to evaluate the product to determine whether or not it will fit your needs. Use of this system for any other purpose, before registration and without our written consent, is expressly forbidden. Registered users are given a non-exclusive license to use this software on any machine that they have access to, but not on more than one at a time (the "treat this software like a book" idea). Registered users may modify the source code provided to suit their needs, but this source code (in original or modified form) may not be distributed without the prior written consent of Fitted Software Tools. Registered users may include compiled portions of the library and runtime support code in the programs by them developed, and use or distribute these programs without payment of any additional license fees to Fitted Software Tools. Support 36 Chapter 11 Support Our basic philosophy is very simple: Without happy users, we do not have a business -- or, at least, we will not have one for long! We will do everything in our power to assure that our users get the kind of support that they deserve and we can afford to provide. Above all, we do not want to create false expectations on the part of our users, the reason for this chapter. We will provide our registered users with support either by mail or through our newly installed BBS, at 404/497-0931. We much prefer that you use our BBS to contact us, if at all possible. The advantages of using the BBS are: all users get immediate notification of bugs and fixes; It encourages users to participate in finding resolution to "how to" type questions. We cannot, of course, promise to fix any bug that you may find within a certain period of time. As a matter of fact, we do not even promise to fix any and all bugs that you may find, but we will try... When a fix is not imminent, we will try to give you a workaround procedure, so that you may go on with your work. As we fix bugs, we will make the new versions of the affected programs available for download from the BBS. Should this not be acceptable to you, you may elect to have the fixes mailed to you, for $5 to cover media and handling charges. We will also make all new product updates available for download. In those cases where a reported bug gets fixed only in a later release of the product, the first user reporting the bug has the option of getting that update by mail for the $5 that we charge to ship bug fixes. Registered users have the option of getting software updates by mail instead of downloading them. The current price of such updates is $12. Your input matters to us 37 Chapter 12 Your input matters to us You can bet that this is serious! We know, and you know, that there are many ways in which this system can be improved. It is in our common interest that we agree on just how (what needs changing, what additional capabilities are needed) and when (let's take care of the more important stuff first!). Maybe you like this software so much that you would hate to see us improve it in the wrong direction (ha, ha, ha)... Maybe you find some weaknesses in this product that make it awkward to use. Maybe even (God forbid!) that one or more of those weaknesses make this software unusable for your purposes. Whichever the case may be, we need to know about it, our future is at stake!!! So, please!, fill out the survey form and send it in. Your comments would be appreciated How did you first learn about this product? --------------------------------------------------------- Where did you get this software from? ( ) us ( ) a bulletin board ( ) a friend phone # ___ ___ ____ ( ) a computer club ( ) a shareware software distributor ( ) other ________________________ Systems you intend to use this software on ( ) PC (8088/8086) ( ) AT (80286) ( ) 80386 Typical system's configuration ( ) hard disk ( ) 512k ( ) 640k ( ) extended memory ( ) expanded memory (EMS, EEMS) ( ) EGA adapter ( ) VGA adapter What programming languages do you use regularly? --------------------------------------------------------- What do you like the most about this system? _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ What do you NOT like about this system? _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ Other comments / suggestions: BUG REPORT We would like to think that our software is bug free, but we have been around a while. Someone once wrote that a bug free program is a program whose bugs have not been uncovered yet. So, if you uncover one of those nasty critters, please provide us with the information below, and whatever else that may help us duplicate the problem. Name_____________________________________________ Company__________________________________________ Address__________________________________________ City, State, Zip_________________________________ Telephone _____________ Version of the software in use: ___________________________ Machine in use (make and model): ___________________________ Memory / Disks / Display type: ___________________________ Operating system used: ___________________________ Other system information that may be pertinent (PATH settings, CONFIG.SYS contents,...) Problem description: ORDER FORM Mail this form to: Fitted Software Tools P.O.Box 956129 Duluth, Ga 30136 to register your copy/copies of the Modula-2 compiler, register/order additional copies, and/or order updates. We distribute the software and documentation on 360k floppies. A printed version of the manual is not available yet. The unauthorized distribution of the library and runtime support source code included in the distribution disks that you receive when you order a registered copy or update is specifically prohibited. This source code is made available to registered users only. If you are ordering multiple copies for your organization (or for you and your friends), we would suggest that you order 1 of the $35 ($39) packages and the rest as $25 ($29) registrations. You may then distribute the number of copies that you ordered from the master that you receive. Name_____________________________________________ Company__________________________________________ Address__________________________________________ City, State, Zip_________________________________ QTY ___ X Registration @ $25.00 (*) _________ ___ X Registration & latest version @ $35.00 (*) _________ ___ X diskette updates @$12.00 _________ 4% Sales tax (GA residents) _________ Total enclosed: _________ If ordering the latest version, please specify how long you are willing to wait for a new, imminent update ____________________ (*) After March 1/1988 the prices are $29 and $39. Table of Contents Chapter 1 Introduction 2 1.1 Hardware requirements 3 1.2 Software requirements 3 1.3 What is new in version 1.1 3 1.4 As version 1.0 becomes history... 4 Chapter 2 Software installation 5 2.1 Theory 5 2.2 Recommended setup for a system with 2 floppy drives 6 2.3 Recommended setup for a hard disk system 7 Chapter 3 A little tour through the system 8 3.1 The tour 8 Chapter 4 The Compiler 11 4.1 Running the compiler 12 4.2 The compilation process 13 4.2.0.1 The input file 13 4.2.0.2 The imported modules 13 4.2.0.3 The output file 14 4.2.0.4 A warning 14 4.3 Compiler directives 14 4.4 Runtime errors 15 4.4.1 Trapping runtime errors in your program 15 4.5 Compiler size limits 16 4.6 The language supported 16 4.6.1 LONGINT and LONGCARD 17 4.6.2 Additional standard procedures 17 4.6.2.1 NEW and DISPOSE 17 4.6.2.2 LONG and SHORT 18 4.7 Objects exported by the pseudo module SYSTEM 18 4.7.0.1 TYPE BYTE 18 4.7.0.2 TYPE WORD 18 4.7.0.3 TYPE ADDRESS 19 4.7.0.4 SEG and OFS 19 4.7.0.5 PROCEDURE ADR 19 4.7.0.6 PROCEDURE FLAT 19 4.7.0.7 PROCEDURE PTR 19 4.7.0.8 PROCEDURE SEGMENT 19 4.7.0.9 PROCEDURE OFFSET 19 4.7.0.10 PROCEDURE NEWPROCESS 20 4.7.0.11 PROCEDURE TRANSFER 20 4.7.0.12 PROCEDURE IOTRANSFER 20 4.7.0.13 ASSEMBLER 20 4.8 The generated object code 21 4.8.1 Data type representation 22 4.8.2 The runtime memory map 22 4.8.3 Procedure calling conventions 23 4.8.3.1 Parameter passing (all except open array parameters) 23 4.8.3.2 Parameter passing (open array parameters) 23 4.8.3.3 Returning values from a function procedure 24 4.9 Module priorities 24 4.10 Memory models 25 Chapter 5 The Text Editor 26 Chapter 6 The Linker 28 6.1 Module keys 29 Chapter 7 Other utilities 30 7.1 Editor configurator 30 7.2 Map file generator 30 7.3 Make and the Makefile generator 31 7.4 The execution profiler 31 Chapter 8 The Library Modules 33 8.1 Release 1.1 libraries 33 Chapter 9 Shareware 34 Chapter 10 License terms 35 Chapter 11 Support 36 Chapter 12 Your input matters to us 37