nasm astrrchr函数 x86

xxx.asm

%define p1 ebp+8

%define p2 ebp+12

%define p3 ebp+16

section .text

  global dllmain

  export astrrchr

dllmain:

  mov eax,1

  ret 12

;------------------------------------------------;

;	扫描字符串以查找字符的最后一次出现。

;------------------------------------------------;

astrrchr:

  push ebp

  mov ebp,esp

  push ebx

  mov ecx,[p1]	; const char *str

  mov eax,[p2]	; int c

  .for:

  mov dl,[ecx]

  test dl,dl

  jz .return

  cmp dl,al

  jne .next

  mov ebx,ecx

  .next:

  inc ecx

  jmp .for

  .return:

  mov eax,ebx

  pop ebx

  mov esp,ebp

  pop ebp

  ret 8

c++:

#include <iostream>

#include <Windows.h>

#include <tchar.h>

#include <string>

typedef int (CALLBACK* astrrchr_t)(const char* str, int c);

astrrchr_t astrrchr;

int main()

{

  HMODULE myDLL = LoadLibraryA("xxx.dll");

  astrrchr = (astrrchr_t)GetProcAddress(myDLL, "astrrchr");

  printf("%s\n", strrchr( "hello world", "o"[0])); // orld

  printf("%s\n", astrrchr("hello world", "o"[0])); // orld

  printf("%s\n", strrchr( "hello world", "l"[0])); // ld

  printf("%s\n", astrrchr("hello world", "l"[0])); // ld

  return 0;

}

巴特西

nasm astrrchr函数 x86

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