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Text File | 1986-11-18 | 13.7 KB | 528 lines

.xlist ;------------------------------------------------------------------------ ;This file contains macros for use with Microsoft's MASM v4.00. ; ;Written by John Friend ;Compuserve ID, 73317,2204 ;Released to the public domain on November 18, 1986 for any use or purpose. ; ;Syntax for using these macros is as follows: ; ;IF STATEMENT: ;------------- ; ;_IF <param1> condition <param2> ; ; <your code for if the condition is satisfied> ; ;_ENDIF ; ; ;IF THEN ELSE STATEMENT: ;----------------------- ; ;_IFELSE <param1> condition <param2> ; ; <your code for if the condition is satisfied> ; ;_ELSE ; ; <your code for if the condition is not satisfied> ; ;_ENDIF ; ; ;WHILE STATEMENT: ;---------------- ; ;_WHILE <param1> condition <param2> ; ; <your code for if the condition is satisfied> ; ;_ENDWHILE ; ; ; ;FOR STATEMENT: ;-------------- ; ;_FOR <param1> eq <startvalue> to <endvalue> step <stepvalue> ; ; <your code for the for loop> ; ;_ENDFOR ; ; ;The macros allow you to create IF, WHILE, and FOR statements in ;assembly language. They work on the principle that any one of the ;above statements can be generated with a combination of cmp and jump ;instructions. ; ;There are a number of tricks used to get these macros to work: ; ;1) A way to generate the appropriate labels is needed. Each label has ; to be unique in order to not get assembler conflicts. This is done ; by keeping a counter of what label number we are on (varcntr) and ; the next time we need a label, we convert varcntr to ascii and insert ; it in the label string. Since varcntr is incremented each time we ; create a new label, we never get two identical labels. ; ;2) IF, WHILE, and FOR statements can be simulated with the inverse ; comparison from what is found in the statement declaration. For example, ; the statement: ; ; IF (ax > 0) then ; begin ; <body of code> ; end ; ; This statement can be simulated with the inverse comparison and a jump ; as follows: ; ; If (ax <= 0) then jump around <body of code> ; <body of code> ; ; In assembly language: ; ; cmp ax,0 ; jbe SKIP_BODY_OF_CODE ; <body of code> ;SKIP_BODY_OF_CODE: ; ; The trick is how to generate the inverse comparison in an assembly macro. ; This is done by comparing the comparison string to a number of pre-defined ; ones using the IFIDN macro command and then substituting the inverse one. ; See the macro OPP_JMP. ; ;3) We want to be able to nest the statements. In order to do this we need ; some kind of a stack where we can push a label name each time we create ; an IF statement and pop the label name each time an ENDIF is ; encountered. This is done using the NAMEPUSH and NAMEPOP. ; ; ;LIMITATIONS: ; ;1) Bodies of code between an _IF statement and an _ENDIF are limited to ; 128 bytes because short jumps are used. This could be increased either ; by using long jumps or creating a separate set of macros with long ; jumps (perhaps preceded with an L). ;2) Statements may only be nested 9 deep. This is the size of the NAMEPUSH ; stack and could be made as large as desired. ;3) Param1 and Param2 may not both be variables. This is because 8088 ; assembly cannot compare two variables directly. The macros could be ; rewritten to move one parameter into a register first and then do the ; compare, but that would cost some code size. I tried to use the .TYPE ; function to discern whether a passed parameter was a constant, a variable ; or a register, but it does not seem to work as specified in the manual ; and there appears to be no way in a macro to tell whether a parameter is ; a variable or not (I could be wrong, but I couldn't find a way). ; ; ;------------------------------------------------------------------------ varcntr = 0 ;init the variable counter ;these 9 variables are used as a stack so we can have nested ;statements savednum1 = 0 ;init the stack variables savednum2 = 0 savednum3 = 0 savednum4 = 0 savednum5 = 0 savednum6 = 0 savednum7 = 0 savednum8 = 0 savednum9 = 0 usesigns equ 0 ;use signed comparisons nosigns equ 1 ;use unsigned comparisons signflag = nosigns ;init to no signs ;to generate signed comparisons, set signflag = usesigns ;------------------------------------------------------------------------ ;Format for the while macro is as follows: ; ;Comparison operators are as follows: ;We can't acutally use the arithmetic symbols (<,>,=,etc) because ;they are treated specially by the assembler not as the literal chars. ; ;gt > ;lt < ;eq = ;gte >= ;lte <= ;ne <> ; ;For example, this statement: ; ;_WHILE ax gt [loopcnt] END_LOOP ; ; <body of while loop> ; ;_ENDWHILE ; ; ;Would generate this code: ; ; cmp ax,[loopcnt] ; jbe END_LOOP ; ; <Body of while loop> ; ;END_LOOP: ; ; ;------------------------------------------------------------------------ _WHILE macro param1,condition,param2 def_label <top_label>,%varcntr ;;define the top label cmp param1,param2 ;;do the comparison opp_jmp <condition>,<bot_label>,%varcntr ;;make the condition jump namepush ;;push varcntr onto the stack ENDM ;------------------------------------------------------------------------ _WHILE2 macro param1,condition,param2 ;;used for comparing two variables def_label <top_label>,%varcntr ;;define the top label mov dx,param2 cmp param1,dx opp_jmp <condition>,<bot_label>,%varcntr ;;make the condition jump namepush ;;push varcntr onto the stack ENDM ;------------------------------------------------------------------------ _ENDWHILE macro gen_jmp2 <top_label>,%savednum1 ;;jump back to the top of the loop def_label <bot_label>,%savednum1 ;;make bottom loop label namepop ;;pop the stack down ENDM ;------------------------------------------------------------------------ DEF_LABEL macro first_text,num ;;make a label with passed text and number &first_text&num label near ENDM ;------------------------------------------------------------------------ ;OPP_JUMP is a macro to generate the opposite comparison of the passed ;condition and generate a jump to a label made from the passed text and ;the ascii characters of the passed number. ; ;There are two types of comparison, either signed comparisons or unsigned ;comparisons depending upon the value of the signflag. Unsigned comparisons ;use comparisons like jbe,jae,ja,jb. Signed comparisons use comparisons like ;jg,jl,jge,jle. ; ;Passed: condition (gt,lt,gte,lte,eq,ne) ; text (for lable) ; number (to be converted to ascii and put in the label) ;------------------------------------------------------------------------ OPP_JMP macro jmp_condition,first_text,num1 ;do an opposite jump to the requested label IF signflag eq nosigns ;;if we should do unsigned comparisons ifidn <jmp_condition>,<gt> jbe &first_text&num1 ;;inverse condition to stop loop else ifidn <jmp_condition>,<eq> jnz &first_text&num1 ;;inverse condition to stop loop else ifidn <jmp_condition>,<lt> jae &first_text&num1 ;;inverse condition to stop loop else ifidn <jmp_condition>,<gte> jb &first_text&num1 ;;inverse condition to stop loop else ifidn <jmp_condition>,<lte> ja &first_text&num1 ;;inverse condition to stop loop else ifidn <jmp_condition>,<ne> jz &first_text&num1 ;;inverse condition to stop loop else if1 %out ERROR - unsupported while condition &jmp_condition .ERR ;;force error endif endif endif endif endif endif endif ELSE ;;else, if we should do signed comparisons ifidn <jmp_condition>,<gt> jle &first_text&num1 ;;inverse condition to stop loop else ifidn <jmp_condition>,<eq> jnz &first_text&num1 ;;inverse condition to stop loop else ifidn <jmp_condition>,<lt> jge &first_text&num1 ;;inverse condition to stop loop else ifidn <jmp_condition>,<gte> jl &first_text&num1 ;;inverse condition to stop loop else ifidn <jmp_condition>,<lte> jg &first_text&num1 ;;inverse condition to stop loop else ifidn <jmp_condition>,<ne> jz &first_text&num1 ;;inverse condition to stop loop else if1 %out ERROR - unsupported while condition &jmp_condition .ERR ;;force error endif endif endif endif endif endif endif ENDIF ENDM ;------------------------------------------------------------------------ GEN_JMP2 macro first_text,num1 jmp &first_text&num1 ENDM ;------------------------------------------------------------------------ ;push the label number onto a stack to allow nesting. NAMEPUSH macro IF savednum9 ne 0 ;;if stack overflows %out ERROR - NAMEPUSH macro overflow. ;;show error msg %out Nesting too deep. .err ;;stop assembly ENDIF savednum9 = savednum8 savednum8 = savednum7 savednum7 = savednum6 savednum6 = savednum5 savednum5 = savednum4 savednum4 = savednum3 savednum3 = savednum2 savednum2 = savednum1 savednum1 = varcntr varcntr = varcntr + 1 ;;inc the counter forever ENDM ;------------------------------------------------------------------------ ;pop a label number off the stack NAMEPOP macro savednum1 = savednum2 savednum2 = savednum3 savednum3 = savednum4 savednum4 = savednum5 savednum5 = savednum6 savednum6 = savednum7 savednum7 = savednum8 savednum8 = savednum9 ENDM ;------------------------------------------------------------------------ _IF macro param1,condition,param2 cmp param1,param2 opp_jmp <condition>,<endif_label>,%varcntr namepush ENDM ;------------------------------------------------------------------------ _IF2 macro param1,condition,param2 ;used for comparing two variables mov dx,param2 cmp param1,dx opp_jmp <condition>,<endif_label>,%varcntr namepush ENDM ;------------------------------------------------------------------------ _ENDIF macro def_label <endif_label>,%savednum1 namepop ;;pop the variable name counter ENDM ;------------------------------------------------------------------------ _IFELSE macro param1,condition,param2 ;if-then-else construct cmp param1,param2 opp_jmp <condition>,<else_label>,%varcntr namepush ENDM ;------------------------------------------------------------------------ _ELSE macro gen_jmp2 <endif_label>,%savednum1 ;first end the above condition by jumping around the else def_label <else_label>,%savednum1 ;now make the label for jumping to the else condition ENDM ;------------------------------------------------------------------------ _ENDIFELSE macro _endif ;same as an endif ENDM ;------------------------------------------------------------------------ _FOR macro loopvar,eq_text,loopvar_init,to_text,loopvar_end,step_text,stepvalue Local AROUND_INC ;;_FOR ax eq 0 to 5 step 1 IF2 IFDIF <&eq_text>,<eq> %out ERROR in _FOR declaration (eq not correct) %out Example: "_FOR ax eq 0 to 5 step 1" %out .err ENDIF IFDIF <&to_text>,<to> %out ERROR in _FOR declaration (to not correct) %out Example: "_FOR ax eq 0 to 5 step 1" %out .err ENDIF IFDIF <&step_text>,<step> %out ERROR in _FOR declaration (step not correct) %out Example: "_FOR ax eq 0 to 5 step 1" %out .err ENDIF ENDIF mov [loopvar],loopvar_init ;;initialize the loop variable jmp short AROUND_INC ;;skip over the increment the first time def_label <top_for>,%varcntr ;;set label at the top of the loop add [loopvar],stepvalue ;;add the step value cmp [loopvar],loopvar_end ;;do the loop comparison opp_jmp <ne>,<bot_for>,%varcntr ;;don't jump if loopvar <> loopvar_end namepush AROUND_INC: ENDM _ENDFOR macro gen_jmp2 <top_for>,%savednum1 ;;jump back to the top of the loop def_label <bot_for>,%savednum1 ;;set label for the end of the loop namepop ;;pop the variable name counter ENDM ;------------------------------------------------------------------------ ;The following macros are for doing long jumps as efficiently as possible. ;They all consist of the regular short jump on condition syntax preceded ;by an "l". For example. These are real handy to fix those assembly errors ;that report "jump out of range". Just put an "l" in front of the ;condition and the macro does all the work. ; ;For example: ; ;ljc label1 ;jump long to label1 if carry set ;ljnz label2 ;jump long to label2 if zero not set ; ;------------------------------------------------------------------------ ljc macro label local short_label jnc short_label ;;use to opposite condition to jump short jmp label short_label: endm ljnc macro label local short_label jc short_label jmp label short_label: endm ljz macro label local short_label jnz short_label ;;use to opposite condition to jump short jmp label short_label: endm ljnz macro label local short_label jz short_label ;;use to opposite condition to jump short jmp label short_label: endm lja macro label local short_label jbe short_label ;;use to opposite condition to jump short jmp label short_label: endm ljb macro label local short_label jae short_label ;;use to opposite condition to jump short jmp label short_label: endm ljae macro label local short_label jb short_label ;;use to opposite condition to jump short jmp label short_label: endm ljbe macro label local short_label ja short_label ;;use to opposite condition to jump short jmp label short_label: endm ljs macro label local short_label jns short_label ;;use to opposite condition to jump short jmp label short_label: endm ljns macro label local short_label js short_label ;;use to opposite condition to jump short jmp label short_label: endm .list