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Text File | 1985-08-11 | 12.0 KB | 443 lines | [TEXT/Anon]

MAC.68K ENDD ENDD ENDD PURPOSE To terminate a DUP block. FORMAT ENDD dupname ENDD DESCRIPTION A unnamed ENDD will always terminate the current DUP or ECHO block even if the block has a dupname. A named ENDD terminates the current block if its dupname matches the block name. A named ENDD will be ignored if its name does not match the active dupname. ENDM ENDM ENDM PURPOSE To end a macro definition. FORMAT ENDM macroname ENDM DESCRIPTION ENDM terminates a macro definition. Accidently ommitting an ENDM results in the apparent loss of code since the following lines are placed into the macro definition and are not assembled. A named ENDM does not terminate a macro defintion unless the macroname matches the MACRO or MACROL being defined. This allows macro definitions to be placed inside a macro definition. A macro nested in this manner will not be defined until the outer level macro is called. MAC.68K -30- MAC.68K ENTRY ENTRY ENTRY PURPOSE To specify relative symbolic entry points for a module assembly. FORMAT ENTRY symbol,symbol,...symbol DESCRIPTION ENTRY is used with MODULE to provide a list of symbol names and offset values that are placed in the module object file. Any symbol name defined in the module may be used. Since modules are assigned an origin address of $0, the symbol values represent a relative offset from the start ($0) of the module. When the object module is later used in another assembly, these $0 relative values will be biased by the current location address in the calling assembly, and the symbol with its new value will be entered into the symbol table. EXAMPLE ENTRY READCH,WRITECH -31- MAC.68K MAC.68K EQU or = EQU or = EQU or = PURPOSE To define a symbol. FORMAT symbol EQU expression symbol = expression DESCRIPTION EQU assigns a permanent value to the symbol name in the location field. Any symbols used in the expression must have been previously defined. If an error is detected the symbol remains undefined, or retains its current value if a redefinition is attempted. EQU may not be used on a symbol previously established as redefinable with a SET, MAX, MIN, or STRCNT. Also any symbol previously established as permanent may not be redefined with EQU, SET, MAX, MIN, or STRCNT. EXAMPLES RESET EQU 0 SAMPLE2 EQU SAMPLE1+1 reset = 0 MAC.68K -32- MAC.68K ERRxx ERRxx ERRxx PURPOSE To force a source line fatal error flag type P. FORMAT ERR ERRxx expression xx = EQ NE GE GT LE LT DESCRIPTION ERRxx can be used to detect and call attention to program errors at assembly time. For example, a macro expansion might do range checks on parameters and force an assembly error if the macro was called with an invalid parameter. ERRxx checks are done during pass 2 and may contain forward symbol references. ERR unconditionally forces a P type source line error. ERRxx compares the value of the expression in the operation field and produces an error if condition xx is true. For example, ERREQ produces an error when the expression value is zero. EXAMPLES ERREQ PAGESIZE ERRGT P1-5 IFS EQ,$P1$$,1 CHECK FOR A NULL PARAMETER ERR P1 IS A REQUIRED PARAMETER EVEN EVEN EVEN PURPOSE To force the location counter to an even boundary. FORMAT EVEN DESCRIPTION If the current location counter is at an odd address, EVEN adds one to its value to set it to an even address boundary. Note that all CPU instructions, word and long word data operations, and section pseudo ops automatically adjust to even word boundaries. -33- MAC.68K MAC.68K GLOBL GLOBL GLOBL PURPOSE To declare external symbol names. FORMAT GLOBL symbol GLOBL symbol,symbol,... DESCRIPTION GLOBL declares symbols to be external. If the symbol is defined in the current assembly, the symbol is written to the .O file as a defined external symbol and becomes available for use in other routines at LO68 link time. If the symbol is undefined in the current assembly, it is written to the .O file as an undefined external symbol and LO68 searches the other load modules to locate the address of the symbol. The -U invocation option sets all undefined symbols as external references. This is useful for C programs which make many references to library routines, but it can mask legitimate undefined symbol names when used with assembler source files. One can use explicit GLOBL statements and avoid the -U option. EXAMPLE GLOBL DUMPMEM,DUMPREG GLOBL CINCO MAC.68K -34- MAC.68K HERE HERE HERE PURPOSE To assemble a block of code saved by previous DEFER(s). FORMAT HERE defname HERE DESCRIPTION HERE inserts all source lines saved by prior similiarly named DEFERs. A HERE with no source lines in its DEFER buffer has no effect on the assembly. EXAMPLE TABLE MACRO P1,P2,P3 CHAR TABLE 'A',1,PROCA DC.B P1 TABLE 'B',2,PROCB T2 DEFER TABLE 'C',3,PROCC DC P2 VALUE DS 0 DEFER T2 HERE T3 DEFER PADDR DS.L 0 DC.L P3 T3 HERE DEFER ENDM generates CHAR DC.B 'A' DC.B 'B' DC.B 'C' VALUE DS 0 DC 1 DC 2 DC 3 PADDR DS.L 0 DC.L PROCA DC.L PROCB DC.L PROCC -35- MAC.68K MAC.68K IDENT IDENT IDENT PURPOSE To identify start of program text, program name, and program absolute origin. FORMAT IDENT IDENT name IDENT name,origin IDENT name,origin,data,bss DESCRIPTION An IDENT is an optional first card in a MAC.68K input source file. If the name field is present, it identifies the program name and is used as the base file name for the object file. Else the source file name is used as the base file name for the object file. In the Macintosh environment the default (and for now the only practical) load address is 0. There is no fixed load address for the Mac, and every assembly language program should be programmed using relative addressing. The only absolute references should be to the operating systems fixed location variables and constants in low memory ($16A - $B00). The following paragraphs describe features available for CPM/68K usage. MAC.68K uses its own load address as the default absolute load origin address for a .68K object file. For an absolute load address higher than $500, the optional origin field may be used to specify the desired address. Once selected, no code may be origined lower than the load address. When generating .68K object files, MAC.68K by default assigns the data and bss segments to be contiguous with the program segment. To specifically assign origins to these segments, the data and bss fields may be used on the IDENT card. These two fields may contain forward symbol references. EXAMPLES IDENT CONVERT IDENT CONVERT,$4000 IDENT TEST,$1000,$4000,$8000 MAC.68K -36-$4000 IDENT TEST,$1000,$4000,$8000 MAC.68K