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65c02 Cross Assembler for Amiga ================================= Supervisor Software 1989 Jukka Marin Version 2.352 Freely distributable as long as all the files are kept together and the copyright notice is not changed. Asm65 is a macro assembler running under AmigaDOS. It was completely written in assembly language to make the executable small (and because I *love* machine language!). I suggest that you would read through this manual. I know that all the topics are not explained exactly where they should be. I'll improve this document sometimes... Command line parameters ========================= Command line syntax is as follows: Asm65 <sourcefile> [-opt] where <sourcefile> is a standard AmigaDOS filename WITHOUT the .asm extension. Asm65 will automatically add the extensions needed to generate the source and list file names. [-opt] may contain one or more of the following options: -l produce a list file (uses name <filename>.lst) -h destination file in hex dump -s dump symbol values after assembling -c enable 65c02 extended addressing modes and instructions Example: Asm65 test -s-l will assemble a file called 'test.asm' in current directory and produce an binary file 'test' as well as a list file 'test.lst' with a symbol table. Source line syntax ==================== The source lines should follow the following format: [label] [mnemonic [operands]] [;comment] The label, if present, must start at the column 1. The first character of a symbol must be i) an alphabetic character (a...z, A...Z) OR ii) an underscore (_) OR iii) a period (.). The rest of the characters can be any of these characters or also numeric (0...9). The symbol names are case-sensitive, so 'test' is different from 'TEST' and 'Test'. The line may or may not contain a mnemonic and its operands. Comments are also optional. The comments must begin with a ';'. Mnemonics may *never* start at column 1. They must always be preceded by at least one blank (a space character or a tabulator). An example listing follows: zpl equ 251 ; free ZP storage on a C-64 zph equ 252 chrout equ $ffd2 ; used to output a char on a C-64 text macro jmp text\@z ; causes a jump over the text db \1 db 13,0 text\@z endm sjmp macro ; short jump ifne @MODE&1 bra \1 ; on a 65c02 bra will be used endc ifeq @MODE&1 jmp \1 ; on a 6502 jmp will be used endc endm * equ $c000 ; sets the destination address ldx #<string ; set the string address ldy #>string stx zpl sty zph ldy #0 ; reset index loop lda (zpl),y ; get a char beq exit ; NULL -> exit jsr chrout ; print it iny bne loop inc zph ; incr. high byte of addr sjmp loop ; get next char exit rts string text 'This is a test!' Symbols ========= The symbols can be defined in three ways: i) using a symbol as a label ii) by the SET directive iii) by the EQU directive If a symbol is defined using the SET directive it may be re-defined using another SET. Labels and EQUated symbols may not be re-defined. * is a special symbol: It must be EQUated to the start address of the compiled code before any code producing lines. That is to tell the assembler where the compiled code will be located in the 6502 address space. Later, the 'asterisk' symbol contains the start address of each line (ie. jmp * will produce an endless loop because it causes a jump to the start of line which in this case is the JMP instruction). All symbols that will be used to address the page zero must be defined *before* they are used. Otherwise the assembler will take the symbols as absolute ones during the first pass until it reads the definition statement. During the second pass the assembler knows that the symbol is a page zero value and a phasing difference will occur. It is recommended to define *all* page zero symbols at the beginning of the source code to avoid any problems. If you use the -s option during assembly the symbol table will be listed after the assembly is completed. The symbol table contains the following fields: symbol_name value type usage Symbol name fields contain the symbol names in alphabetical order. Value is the symbol value in hexadecimal. Type indicates the way in which the symbol was defined: S means it was SET, E that it was EQUated, and Z means that the value is a page zero address. The assembler creates page zero references always when it is possible to use page zero addressing instead of absolute addressing. If the page zero addressing mode is not available the absolute addressing will be used instead. Numbers ========= The assembler accepts numbers in decimal (default), hexadecimal (preceded by '$'), octal (preceded by '&'), in quinary (preceded by '^') and in binary (preceded by '%'). An ASCII character can also be used but it must be enclosed in single quotes (eg. 'A' = 65 = $41 = %1000001 = &101). Expression evaluation ======================= All expressions are evaluated from left to right BUT the *, /, and \ operators have higher priority than the others and will be handled before addition and subtraction, for example. The expressions enclosed in [] will be evaluated first. The assembler knows the following operators: oper. operation example + addition symbol+5 - subtraction 78-43 * multiplication 10*length / division buffer/8 \ modulo operation length\4 & logical AND address&7 ! logical OR bit!1 ^ logical Exclusive OR bit^1 < logical shift left bit<5 > logical shift right number>2 - negation (2's compelment) -332 ~ logical NOT (1's complement) ~10 < get low byte only <address > get high byte only >address @MODE gets the current MODE value @MODE $ a hex number $ffd2 & an octal number &777 ^ a quinary number ^0123 % a binary number %10111010101 '' ASCII code conversion 'J' With < and > you can separate the high and low bytes of an absolute address. For example: pointerlow equ 251 pointerhigh equ 252 ... ldx #<TABLE ldy #>TABLE stx pointerlow sty pointerhigh ldy #0 loop lda (pointerlow),y adc temp ... TABLE db 0,5,2,7,3,8,4,9,-1 The system variable @MODE contains some information about the options used when starting the assembler. Currently only the lowest five bits of the variable are used: bit# meaning 0 if '1' the assembler operates in 65c02 mode (otherwise in 6502 mode) 1 if '1' the assembler is producing a hex object file (not binary) 2 if '1' the assembler will produce a symbol table after assembly 3 if '1' the assembler is producing a list file 4 if '1' the assembler is compiling an include file This way you can make 'intelligent' macros that will utilize the extra addressing modes and instructions of the 65c02 when the compiler is operating in 65c02 mode. Otherwise you could write your own code to achieve the same function using only 6502 instructions. You can check the @MODE variable with the conditional assembly direc- tives: sjmp macro ;short jump ifne @MODE&1 bra \1 ; on a 65c02 bra will be used endc ifeq @MODE&1 jmp \1 ; on a 6502 jmp will be used endc endm Conditional assembly ====================== (and other directives) The Asm65 cross assembler supports conditional assembly. The conditional blocks may be nested; maximum nesting level is currently set to 16. The conditional assembly directives are listed below: dir. operation example IFEQ assemble if expression = 0 IFEQ version-5 IFNE assemble if expression <> 0 IFNE debug IFGT assemble if expression > 0 IFGT version-4 IFLT assemble if expression < 0 IFLT test IFGE assemble if expression >= 0 IFLE assemble if expression =< 0 IFD assemble if symbol defined IFD debug IFND assemble if symbol not defined IFND debug IFC assemble if strings identical IFC '\1','test' IFNC assemble if strings not ident. IFNC '\1','' IFI assemble if the second string contains the first string IFNI assemble if the second string does not contain the first string ENDC end of conditional assembly block FAIL cause assembly to fail PAGE inserts a page break into the list file With IFI and IFNI you can test if a macro parameter contains a specific character, for example. Macros ======== Any macros must be defined before they are used in the program code. The macro definitions may not be nested but it is allowed to call another macro from within a macro. The maximum macro nesting level is currently set to 8. The first four parameters are passed to the macro while the rest are discarded. You can handle the parameters within a macro by using a backslash followed with the parameter number (eg. \3 is the third parameter of the macro). If no parameter is given to the macro the parameters will be NULL (ie. ''). You can use the conditional assembly directives to analyse the macro parameters (you can check if the parameter is empty with IFC '\1','' or see whether it contains a known string with IFI 'reg','\2'). The macro definition is done as follows: text macro ; create a macro called 'text' db \1 ; stores the first param. into memory db 13,0 ; adds CR and NULL to the end of string endm ; ends the macro definition NOTE: No label is allowed on the ENDM line. The macro can be called later using the macro name as a directive: ... text 'Test string for a macro!' text 'Another line of text.' ... If a macro parameter like 10,13,34 is needed it must be enclosed in < and > characters. Otherwise each individual number will be taken as a separate macro parameter. ... text <'This',32,'is only',32,'a single parameter!'> ... Within macros you may use special labels whose names start with '\@' to generate unique label names. The '\@' will be converted into a four character hexadecimal number (0001...ffff). This number is incremented each time a symbol with '\@' is defined. Example: test macro jmp test\@ db \1 test\@ ; Note: the ENDM line may NOT endm ; contain a label. Storage allocation: ===================== To allocate storage for variables you can use the define directive: counter db 4 ; allocates one byte and sets it to 4. jumpaddr dw routine ; allocates two bytes and store the ; value of 'routine' into memory (low ; byte first). hugevalue dl $654312 ; allocates four bytes and writes the ; number into them (the least significant ; byte is stored at the lowest address) Other examples: text db 'This is a string!',13,'Another line.',13,0 adrtable dw load,save,help,quit Including other files ======================= You can include additional header files using the INCLUDE directive. The syntax is INCLUDE 'filename' where filename is a standard AmigaDOS filename with an optional path. The maximum nesting level of nested include files is currently set to 8. The MODE directive ==================== You can set or change several assembler parameters using the MODE directive. The syntax is MODE <let>[<let>[<let>...]] A lower case character turns an option OFF and an upper case character turns the option ON. The options currently supported are listed below: C 65c02 mode L start/stop writing to list file S produce the symbol table H produce a hex object file (NOTE: No .hex extension is added to the filename when using the MODE H directive instead of the -h option on the command line) You may, for example, prevent the included files to be written into the list file using the command 'MODE l' at the first line of the include file and the command 'MODE L' on the last line. If the list file was not enabled using the -l option on the command line the 'MODE L' command will have no effect. The output file formats ========================= The binary object file When no -h option or MODE H command is used the assembler will produce a pure binary object file which can be executed by the 65(c)02 as it is. No extra bytes are added to the compiled data. The hex object file If the option -h is used the compiler will replace all bytes of the object code with two ASCII hex characters (ie. 00...FF). There will be no spaces or line feeds between the hex numbers (the file will only contain one string). At the end of the file a CTRL+Z character is added. The list file When the option -l is used on the command line the compiler will write a list file on the disk. The list file is divided into pages by FF (12) characters. A title and a page number will be written at the top of each page. The rows of the list file contain several fields: line# addr bytes symbol mnem operands comments ===== ==== ===== ====== ==== ======== ======== 65c02 Cross Assembler v2.34 (c) J. & T. Marin 1988 -- Page # 1 -- 00001 00002 =00fb zpl equ 251 ; free ZP storage on a C-64 00003 =00fc zph equ 252 00004 =ffd2 chrout equ $ffd2 ; used to output a char on a C-64 00005 00006 text macro 00007 jmp text\@z ; causes a jump over the text 00008 db \1 00009 db 13,0 00010 text\@z 00011 endm 00012 00013 00014 sjmp macro ; short jump 00015 ifne @MODE&1 00016 bra \1 ; on a 65c02 bra will be used 00017 endc 00018 ifeq @MODE&1 00019 jmp \1 ; on a 6502 jmp will be used 00020 endc 00021 endm 00022 00023 00024 00025 =c000 * equ $c000 ; sets the destination address 00026 00027 c000 a2 19 ldx #<string ; set the string address 00028 c002 a0 c0 ldy #>string 00029 c004 86 fb stx zpl 00030 c006 84 fc sty zph 00031 c008 a0 00 ldy #0 ; reset index 00032 c00a b1 fb loop lda (zpl),y ; get a char 00033 c00c f0 0a beq exit ; NULL -> exit 00034 c00e 20 d2 ff jsr chrout ; print it 00035 c011 c8 iny 00036 c012 d0 f6 bne loop 00037 c014 e6 fc inc zph ; incr. high byte of addr 00038M sjmp loop ; get next char 00038M TRUE ifne @MODE&1 00038M c016 80 f2 bra loop ; on a 65c02 bra will be used 00038M endc 00038M FALSE ifeq @MODE&1 00038M jmp loop ; on a 6502 jmp will be used 00038M endc 00039 00040 c018 60 exit rts 00041 00042M string text 'This is a test!' 00042M c019 4c 2d c0 jmp text0002z ; causes a jump over the text 00042M c01c 54 68 69 db 'This is a test!' 00042M c02b 0d 00 db 13,0 00042M text0002z 00043 00044 65c02 Cross Assembler v2.34 (c) J. & T. Marin 1988 -- Page # 2 -- symbol_name value type usage symbol_name value type usage chrout ffd2 e 1 exit c018 1 loop c00a 2 string c019 2 text0002z c02d 1 zph 00fc ze 2 zpl 00fb ze 2 The leftmost field shows the source line number. If the line is generated by macro expansion an 'M' will be added to the line number. Lines derived from included files are marked with 'I'. The next field contains the destination address in hexadecimal, or the value SET or EQUated to a symbol. If SET was used the value is preceded with a '>' and if EQU was used by a '='. If the line contained a conditional assembly directive the address field will be replaced with 'TRUE' or 'FALSE' depending on the result on the condition test. The third field contains the first three object bytes generated from this line. The fourth field contains the symbol name, fifth the mnemonic and sixth the operands. The last field contains the comments. The columns of the fields depend on the number of tabulators being used in the source file. ------------------------------------------------------------------------- Known bugs: - lda #-1-8 causes an error message although it shouldn't. - Strange line numbers in some error messages (in errors with macros and include files). ------------------------------------------------------------------------- Send all flames/thanks/bug_reports/whatever to: MAIL: Jukka Marin Ruskeisentie 24 70900 Toivala FINLAND E-MAIL: jmarin@finkuo.bitnet If you like this program I would appreciate a small donation from you. You know, it takes some time to write a macro assembler... The source code is now included with the executables. To compile the source you need special macro libraries, however. I know the source is *terrible* and not suitable to be used as an example of assembly language programming. Thanks! -jm