125 lines
3.3 KiB
NASM
125 lines
3.3 KiB
NASM
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; Copyright (c) Mix Software 1988
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;
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; Setjmp - stores the current state to allow a
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; global branch to be taken later.
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;
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; Declared in C as:
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; struct JMP_BUF {
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; int frame;
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; long pc;
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; int stacktop;
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; char save[22];
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; };
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; int setjmp();
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;
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; Example of use in C:
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;
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; { JMP_BUF sjbuf;
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; if (setjmp(&sjbuf)) {
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; /* code that is jumped to */
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; }
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; else {
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; /* code to execute after setting the jump */
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; } }
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;
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;
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FRAME EQU 0 ; Frame pointer in jmp_buf
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PC EQU 2 ; Program counter in jmp_buf
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STACKTOP EQU 6 ; Stack top in jmp_buf
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SAVESIZE EQU 8 ; Size of parameter area
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SAVE EQU 10 ; Save stack area in jmp_buf
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MAXDATA EQU 22 ; Limit on top of stack data
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IDT setjmp
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DEF setjmp
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IF UPPER
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DEF SETJMP
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ENDIF
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setjmp equ $
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SETJMP MOV BX,SP ; Point to return address
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MOV DI,[BX][%PARM1-2] ; address of jmp_buf
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MOV [DI][%FRAME],BP
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MOV AX,[BX]
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MOV [DI][%PC],AX ; First word of pc
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MOV AX,[BX][%2]
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MOV [DI][%PC+2],AX ; Second word of pc
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LEA SI,[BX][%4] ; Top of stack
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MOV [DI][%STACKTOP],SI
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MOV CX,BP
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SUB CX,SI ; Top of stack area
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MOV [DI][%SAVESIZE],CX
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CMP CX,MAXDATA
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JBE SAVESTK
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MOV CX,MAXDATA
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SAVESTK ADD DI,%SAVE
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MOV AX,DS
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MOV ES,AX
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JCXZ DONE
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CLD
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REP
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MOVSB
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DONE XOR AX,AX ; return 0
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RETSEG
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END
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;
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; Longjmp - transfers to the location previously
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; set by a call to setjmp. The stack is
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; also restored to its former state.
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;
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; Declared in C as:
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; struct JMP_BUF {
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; int frame;
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; long pc;
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; int stacktop;
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; int save[22];
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; }
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; int longjmp();
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;
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; Example of use in C:
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;
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; longjmp(&sjbuf,result);
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;
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;
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;
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;
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FRAME EQU 0 ; Frame pointer in jmp_buf
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PC EQU 2 ; Program counter in jmp_buf
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STACKTOP EQU 6 ; Stack top in jmp_buf
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SAVESIZE EQU 8 ; Size of saved stack
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SAVE EQU 10 ; Save stack area in jmp_buf
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MAXDATA EQU 22 ; Limit on top of stack data
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IDT longjmp
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DEF longjmp
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IF UPPER
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DEF LONGJMP
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ENDIF
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longjmp equ $
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LONGJMP MOV BX,SP ; parameter pointer
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MOV SI,[BX][%PARM1-2] ; Address of sjbuf
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CMP SP,[SI][%STACKTOP]
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JA NOFRAME
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MOV AX,[BX][%PARM2-2] ; result
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MOV DI,[SI][%STACKTOP]
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MOV CX,DS
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MOV ES,CX
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MOV CX,[SI][%SAVESIZE]
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CMP CX,MAXDATA
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JA TOOBIG
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PUSH SI
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ADD SI,%SAVE
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JCXZ MOVED
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CLD
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REP
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MOVSB
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MOVED POP SI
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MOV BP,[SI][%FRAME]
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MOV SP,[SI][%STACKTOP]
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PUSH [SI][%PC+2]
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PUSH [SI][%PC]
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RETSEG ; AX has result
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NOFRAME MOV AX,-1
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RETSEG
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TOOBIG MOV AX,-2
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RETSEG
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END
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