将近半个小时，把一小段简短的汇编代码写成了C语言代码

我自己看，感觉好像一句一句翻译的，写得很是生硬，不如书上写的灵活

0040137E    8B7424 04       MOV ESI,DWORD PTR SS:[ESP+4]
00401382    56              PUSH ESI
00401383    8A06            MOV AL,BYTE PTR DS:[ESI]
00401385    84C0            TEST AL,AL
00401387    74 13           JE SHORT serial.0040139C
00401389    3C 41           CMP AL,41
0040138B    72 1F           JB SHORT serial.004013AC
0040138D    3C 5A           CMP AL,5A
0040138F    73 03           JNB SHORT serial.00401394
00401391    46              INC ESI
00401392  ^ EB EF           JMP SHORT serial.00401383
00401394    E8 39000000     CALL serial.004013D2
00401399    46              INC ESI
0040139A  ^ EB E7           JMP SHORT serial.00401383
0040139C    5E              POP ESI
0040139D    E8 20000000     CALL serial.004013C2
004013A2    81F7 78560000   XOR EDI,5678
004013A8    8BC7            MOV EAX,EDI
004013AA    EB 15           JMP SHORT serial.004013C1
004013AC    5E              POP ESI
004013AD    6A 30           PUSH 30
004013AF    68 60214000     PUSH serial.00402160
004013B4    68 69214000     PUSH serial.00402169
004013B9    FF75 08         PUSH DWORD PTR SS:[EBP+8]
004013BC    E8 79000000     CALL <JMP.&USER32.MessageBoxA>
004013C1    C3              RETN
004013C2    33FF            XOR EDI,EDI
004013C4    33DB            XOR EBX,EBX
004013C6    8A1E            MOV BL,BYTE PTR DS:[ESI]
004013C8    84DB            TEST BL,BL
004013CA    74 05           JE SHORT serial.004013D1
004013CC    03FB            ADD EDI,EBX
004013CE    46              INC ESI
004013CF  ^ EB F5           JMP SHORT serial.004013C6
004013D1    C3              RETN
004013D2    2C 20           SUB AL,20
004013D4    8806            MOV BYTE PTR DS:[ESI],AL
004013D6    C3              RETN

int fun(char *str)
{
 char *temp = str;
 int j = 0;
 int i;
 for( i = 0 ; ; i++ )
 {
  if( temp == '\0' )
  {
   break;
  }
  if( temp < 0x41 )
  {
   //return MessageBoxA(handle , "重试" , "出错" , 30);
  }
  if( temp > 0x5A )
  {
   temp -= 0x20;
  }
 }
 for( i = 0 ; ; i++ )
 {
  if( temp == '\0' )
  {
   break;
  }
  j += (int)temp;
 }
 j = j ^ 0x5678;
 return j;
}