ASM+C : 어셈블리와 C언어 결합
컴파일
ml /c /coff /Zi strsch.asm
cl /c main_strsch.c
cl main_strsch.obj strsch.obj
내용
- 입력받은 단어중 해당단어의 위치를 찾는 함수를 어셈블리로 만든다
<main_strsch.c>
#include <stdio.h>
extern int strsch (char *, char*);
int main ()
{
char src[80];
char key[80];
int iRet;
printf (" String to search?");
scanf ("%s", src);
printf (" Key to search for?");
scanf ("%s", key);
iRet = strsch (src,key);
if (0 == iRet)
{
printf (" The key does not appear in the string.\n");
}
else
{
printf (" The key appears at position [%d] in the string\n", iRet);
}
return 0;
}
|
<strsch.asm>
; 2013.10.14
.386
.MODEL FLAT
;INCLUDE io.h
PUBLIC _strsch
.STACK 4096
.DATA
trgtLength DWORD ?
keyLength DWORD ?
lastPosn DWORD ?
.CODE
_strsch PROC NEAR32
;entry code
PUSH EBP
MOV EBP, ESP
mov eax, [ebp+8] ; find length of string
push eax ; length parameter
call strlen
mov trgtLength, eax ; save length of ebp+8
mov eax, [ebp+12] ; find length of string
push eax
call strlen
mov keyLength, eax ; save length of ebp+12
; calculate last position of ebp+8 to check
mov eax,trgtLength
sub eax,keyLength
inc eax ; trgtLength - ebp+12Length + 1
mov lastPosn, eax
cld ; left to right comparison
mov eax,1 ; starting position
whilePosn: cmp eax,lastPosn ; position <= last_posn?
jnle endWhilePosn ; exit if past last position
mov esi,[ebp+8] ; address of ebp+8 string
add esi,eax ; add position
dec esi ; address of position to check
mov edi,[ebp+12] ; address of ebp+12
mov ecx,keyLength ; number of positions to check
repe cmpsb ; check
jz found ; exit on success
inc eax ; increment position
jmp whilePosn ; repeat
endWhilePosn:
mov eax,0
found:
; exit code
MOV ESP, EBP
POP EBP
RET
_strsch ENDP
strlen PROC NEAR32
; find length of string whose address is passed on stack
; length returned in EAX
push ebp ; establish stack frame
mov ebp, esp
pushf ; save flags
push ebx ; and EBX
sub eax, eax ; length := 0
mov ebx, [ebp+8] ; address of string
whileChar: cmp BYTE PTR [ebx], 0 ; null byte?
je endWhileChar ; exit if so
inc eax ; increment length
inc ebx ; point at next character
jmp whileChar ; repeat
endWhileChar:
pop ebx ; restore registers and flags
popf
pop ebp
ret 4 ; return, discarding parameter
strlen ENDP
END
|
