Ok.
I need to read a block of memory from another program every time this
program reachs a certain location in its code. I dont have its source
code so my idea is to write a isr (60h) and change the location i want
to be warned to cd 60. Here is the piece of the program=B4s code
disassemled. THE location is 071a:0d3c:
071A:00000D37 50 PUSH AX
071A:00000D38 51 PUSH CX
071A:00000D39 52 PUSH DX
071A:00000D3A 56 PUSH SI
071A:00000D3B 57 PUSH DI
071A:00000D3C 33 DB XOR BX,BX <<<<LOCATION
071A:00000D3E B9 F0 03 MOV CX,03F0 Change
it to CD 60
071A:00000D41 BA 83 07 MOV DX,0783
071A:00000D44 B3 03 MOV BL,03
071A:00000D46 E8 E7 00 CALL (+00E7)
071A:00000D49 8A 1C MOV BL,[SI]
071A:00000D4B E8 E2 00 CALL (+00E2)
;071A:00000E30
071A:00000D4E 02 FB ADD BH,BL
071A:00000D50 46 INC SI
071A:00000D51 E2 EE LOOP (-12)
;071A:00000D41
071A:00000D53 5F POP DI
071A:00000D54 5E POP SI
071A:00000D55 5A POP DX
071A:00000D56 59 POP CX
071A:00000D57 58 POP AX
071A:00000D58 C3 RET
071A:00000E30 50 PUSH AX
071A:00000E31 53 PUSH BX
071A:00000E32 51 PUSH CX
071A:00000E33 52 PUSH DX
071A:00000E34 E8 C5 FF CALL (-003B)
;071A:00000DFC
071A:00000E37 E8 9F FF CALL (-0061)
;071A:00000DD9
071A:00000E3A BA 80 07 MOV DX,0780
071A:00000E3D EC IN AL,DX
071A:00000E3E A8 08 TEST AL,08
071A:00000E40 74 F5 JZ (-0B)
;071A:00000E37
071A:00000E42 A8 02 TEST AL,02
071A:00000E44 75 F1 JNZ (-0F)
;071A:00000E37
071A:00000E46 BA 83 07 MOV DX,0783
071A:00000E49 8A C3 MOV AL,BL
071A:00000E4B EE OUT DX,AL
071A:00000E4C 5A POP DX
071A:00000E4D 59 POP CX
071A:00000E4E 5B POP BX
071A:00000E4F 58 POP AX
071A:00000E50 C3 RET
Analysing this piece I see that SI points data in the buffer. At that
location, SI is already set to the correct address. My question is what
do i have to do to have that address in my isr? I tried this:
void interrupt int60(void)
{
void *pt;
unsigned ids, isi;
asm{
mov ax, word ptr[bp+6];
mov ids, ax
mov ax, word ptr[bp+4];
mov isi, ax;
}
pt =3D MK_FP(ids, isi);
......
asm mov word ptr[bp+14], 0x61; //To satisfy bx value in the main
program
}
I know those stack locations are correct because I disassembled my isr
code and saw the pushes and pops.
My knowledge in 8086 assembly is limited, and probably im wrong about
the registers Im using. If someone could help me I=B4d appreciate very
much.
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