反汇编--C语言(循环)

int func(int a,int b)
{
 int c=a+b;
 int i;
 for(i=0;i<50;i++){
  c=c+i;
 }
 return c;
}
void main(){
 int sum;
 sum=func(2,5);
 return 0;
}

1:
2: int func(int a,int b)
3: {
//初始工作,和前面一致。
00401020 push ebp
00401021 mov ebp,esp
00401023 sub esp,48h
00401026 push ebx
00401027 push esi
00401028 push edi
00401029 lea edi,[ebp-48h]
0040102C mov ecx,12h
00401031 mov eax,0CCCCCCCCh
00401036 rep stos dword ptr [edi]
//这里进行加法运行 变量a、b、c都从堆栈中取出
4: int c=a+b;
00401038 mov eax,dword ptr [ebp+8]
0040103B add eax,dword ptr [ebp+0Ch]
0040103E mov dword ptr [ebp-4],eax
5: int i;
6: for(i=0;i<50;i++){
//将局部变量 i 置0   i从堆栈中取出
00401041 mov dword ptr [ebp-8],0
//跳转到00401053 处执行 比较i的值
00401048 jmp func+33h (00401053)
//这里用ecx寄存器装载变量i的值 进行累加
0040104A mov ecx,dword ptr [ebp-8]
0040104D add ecx,1
00401050 mov dword ptr [ebp-8],ecx
//这里用 i 和 50(32h) 比较
00401053 cmp dword ptr [ebp-8],32h
//大于或者等于则跳转到00401064处 
00401057 jge func+44h (00401064)
//进行加法运算 局部变量c的值从栈中取出
7: c=c+i;
00401059 mov edx,dword ptr [ebp-4]
0040105C add edx,dword ptr [ebp-8]
0040105F mov dword ptr [ebp-4],edx
8: }
//无条件跳转到0040104a处进行循环累加
00401062 jmp func+2Ah (0040104a)
9: return c;
//循环结束,将变量c的值赋给eax, eax保存返回值
00401064 mov eax,dword ptr [ebp-4]
10: }
//恢复各个寄存器的值
00401067 pop edi
00401068 pop esi
00401069 pop ebx
0040106A mov esp,ebp
0040106C pop ebp
//返回
0040106D ret

//主函数调用相同
11:
12: void main(){
00401070 push ebp
00401071 mov ebp,esp
00401073 sub esp,44h
00401076 push ebx
00401077 push esi
00401078 push edi
00401079 lea edi,[ebp-44h]
0040107C mov ecx,11h
00401081 mov eax,0CCCCCCCCh
00401086 rep stos dword ptr [edi]
13: int sum;
14: sum=func(2,5);
00401088 push 5
0040108A push 2
0040108C call @ILT+5(_func) (0040100a)
00401091 add esp,8
00401094 mov dword ptr [ebp-4],eax
15: return 0;
16: }
00401097 pop edi
00401098 pop esi
00401099 pop ebx
0040109A add esp,44h
0040109D cmp ebp,esp
0040109F call __chkesp (0040d470)
004010A4 mov esp,ebp
004010A6 pop ebp
004010A7 ret

int func(int a,int b)
{
  int c=a+b;
  int i;
  while(c<100){
  c=c+i;
  }
 return c;
}
void main(){
 int sum;
 sum=func(2,5);
 return 0;
}

//前面的基本相同 不做详解
5: while(c<100){
//这里比较变量C和100(64h)的值
00401041 cmp dword ptr [ebp-4],64h
//大于或者等于则跳转到00401052处退出循环
00401045 jge func+32h (00401052)
6: c=c+i;
//加法运算
00401047 mov ecx,dword ptr [ebp-4]
0040104A add ecx,dword ptr [ebp-8]
0040104D mov dword ptr [ebp-4],ecx
7: }
//无条件跳转到00401041处继续进行比较
00401050 jmp func+21h (00401041)
8: return c;
00401052 mov eax,dword ptr [ebp-4]
9: }
00401055 pop edi
00401056 pop esi
00401057 pop ebx
00401058 mov esp,ebp
0040105A pop ebp
0040105B ret

int func(int a,int b)
{
  int c=a+b;
  int i;
 do{
    c=c+i;
}while(c<100);
 return c;
}
void main(){
 int sum;
 sum=func(2,5);
 return 0;
}

//前面的基本相同 不做详解
5: do{
6: c=c+i;
00401041 mov ecx,dword ptr [ebp-4]
00401044 add ecx,dword ptr [ebp-8]
00401047 mov dword ptr [ebp-4],ecx
7: }while(c<100);
//用变量c和100(64h)作比较
0040104A cmp dword ptr [ebp-4],64h
//小于则跳转到00401041处执行循环体内加法
0040104E jl func+21h (00401041)
8: return c;
00401050 mov eax,dword ptr [ebp-4]
9: }
00401053 pop edi
00401054 pop esi
00401055 pop ebx
00401056 mov esp,ebp
00401058 pop ebp
00401059 ret