整理的VC6编译出来表达式语句一些常见的反汇编笔记。

整数

赋值

5:        int a = 1;
0040102E   mov         dword ptr [ebp-4],1
6:        int b = 2;
00401035   mov         dword ptr [ebp-8],2
7:        int c = 5;
0040103C   mov         dword ptr [ebp-0Ch],5
8:        int d = -5;
00401043   mov         dword ptr [ebp-10h],0FFFFFFFBh   # 负数是以补码形式保存在计算机的

加法

10:       int add = a + b;
0040104A   mov         eax,dword ptr [ebp-4]
0040104D   add         eax,dword ptr [ebp-8]
00401050   mov         dword ptr [ebp-14h],eax

减法

11:       int sub = a - b;
00401053   mov         ecx,dword ptr [ebp-4]
00401056   sub         ecx,dword ptr [ebp-8]
00401059   mov         dword ptr [ebp-18h],ecx

乘法

12:       int mul = c * b;
0040105C   mov         edx,dword ptr [ebp-0Ch]
0040105F   imul        edx,dword ptr [ebp-8]
00401063   mov         dword ptr [ebp-1Ch],edx

除法

13:       int div = c / b;
00401066   mov         eax,dword ptr [ebp-0Ch]
00401069   cdq
0040106A   idiv        eax,dword ptr [ebp-8]
0040106D   mov         dword ptr [ebp-20h],eax  # eax保存商值

求余

14:       int rem = c % b;
00401070   mov         eax,dword ptr [ebp-0Ch]
00401073   cdq
00401074   idiv        eax,dword ptr [ebp-8]
00401077   mov         dword ptr [ebp-24h],edx  # edx 保存余数

浮点数

赋值

16:       float aF = 1.1;
0040107A   mov         dword ptr [ebp-28h],3F8CCCCDh
17:       float bF = 2.2;
00401081   mov         dword ptr [ebp-2Ch],400CCCCDh
18:       float cF = 5.5;
00401088   mov         dword ptr [ebp-30h],40B00000h
19:       float dF = -5.5;
0040108F   mov         dword ptr [ebp-34h],0C0B00000h

加法

21:       float fadd = aF + bF;
00401096   fld         dword ptr [ebp-28h]
00401099   fadd        dword ptr [ebp-2Ch]
0040109C   fstp        dword ptr [ebp-38h]

减法

22:       float fsub = aF - bF;
0040109F   fld         dword ptr [ebp-28h]
004010A2   fsub        dword ptr [ebp-2Ch]
004010A5   fstp        dword ptr [ebp-3Ch]

乘法

23:       float fmul = cF * bF;
004010A8   fld         dword ptr [ebp-30h]
004010AB   fmul        dword ptr [ebp-2Ch]
004010AE   fstp        dword ptr [ebp-40h]

除法

24:       float fdiv = cF / bF;
004010B1   fld         dword ptr [ebp-30h]
004010B4   fdiv        dword ptr [ebp-2Ch]
004010B7   fstp        dword ptr [ebp-44h]

布尔（C++）

赋值

5:        bool b = false;
00401178   mov         byte ptr [ebp-4],0	# 本质是int变量，0为假，非零为真

! (非)

6:        bool temp = !b;
0040117C   mov         eax,dword ptr [ebp-4]
0040117F   and         eax,0FFh
00401184   neg         eax
00401186   sbb         eax,eax
00401188   inc         eax
00401189   mov         byte ptr [ebp-8],al

自增

i++

26:       int i = 1;
004010BA   mov         dword ptr [ebp-48h],1
27:       int temp = i++;
004010C1   mov         eax,dword ptr [ebp-48h]
004010C4   mov         dword ptr [ebp-4Ch],eax  # 先赋值
004010C7   mov         ecx,dword ptr [ebp-48h]
004010CA   add         ecx,1                    # 再自增
004010CD   mov         dword ptr [ebp-48h],ecx

++i

28:       temp = ++i;
004010D0   mov         edx,dword ptr [ebp-48h]
004010D3   add         edx,1                    # 先自增
004010D6   mov         dword ptr [ebp-48h],edx
004010D9   mov         eax,dword ptr [ebp-48h]
004010DC   mov         dword ptr [ebp-4Ch],eax  # 再赋值

三目运算符

? :

30:       temp = a > b ? a : b;
004107AF   mov         ecx,dword ptr [ebp-4]
004107B2   cmp         ecx,dword ptr [ebp-8]
004107B5   jle         main+0DFh (004107bf)
004107B7   mov         edx,dword ptr [ebp-4]
004107BA   mov         dword ptr [ebp-50h],edx
004107BD   jmp         main+0E5h (004107c5)
004107BF   mov         eax,dword ptr [ebp-8]
004107C2   mov         dword ptr [ebp-50h],eax
004107C5   mov         ecx,dword ptr [ebp-50h]
004107C8   mov         dword ptr [ebp-4Ch],ecx

位运算符

& (与)

32:       temp = a & b;
004107CB   mov         edx,dword ptr [ebp-4]
004107CE   and         edx,dword ptr [ebp-8]
004107D1   mov         dword ptr [ebp-4Ch],edx

| (或)

33:       temp = a | b;
004107D4   mov         eax,dword ptr [ebp-4]
004107D7   or          eax,dword ptr [ebp-8]
004107DA   mov         dword ptr [ebp-4Ch],eax

<< (左移)

39:       temp = a << 2;
00410C8D   mov         ecx,dword ptr [ebp-4]
00410C90   shl         ecx,2
00410C93   mov         dword ptr [ebp-4Ch],ecx

>> (右移)

40:       temp = d >> 2;
00410C96   mov         edx,dword ptr [ebp-10h]
00410C99   sar         edx,2
00410C9C   mov         dword ptr [ebp-4Ch],edx

! (非)

34:       temp = !a;
004107DD   xor         ecx,ecx
004107DF   cmp         dword ptr [ebp-4],0
004107E3   sete        cl
004107E6   mov         dword ptr [ebp-4Ch],ecx

^ (异或)

41:       temp = a ^ b;
00410C9F   mov         eax,dword ptr [ebp-4]
00410CA2   xor         eax,dword ptr [ebp-8]
00410CA5   mov         dword ptr [ebp-4Ch],eax

~ (取反)

42:       temp = ~a;
00410CA8   mov         ecx,dword ptr [ebp-4]
00410CAB   not         ecx
00410CAD   mov         dword ptr [ebp-4Ch],ecx

逻辑运算符

&& (逻辑与)

36:       temp = a && b;
004107E9   cmp         dword ptr [ebp-4],0
004107ED   je          main+11Eh (004107fe)
004107EF   cmp         dword ptr [ebp-8],0
004107F3   je          main+11Eh (004107fe)
004107F5   mov         dword ptr [ebp-54h],1
004107FC   jmp         main+125h (00410805)
004107FE   mov         dword ptr [ebp-54h],0
00410805   mov         edx,dword ptr [ebp-54h]
00410808   mov         dword ptr [ebp-4Ch],edx

|| (逻辑或)

37:       temp = a || b;
0041080B   cmp         dword ptr [ebp-4],0
0041080F   jne         main+140h (00410820)
00410811   cmp         dword ptr [ebp-8],0
00410815   jne         main+140h (00410820)
00410817   mov         dword ptr [ebp-58h],0
0041081E   jmp         main+147h (00410827)
00410820   mov         dword ptr [ebp-58h],1
00410827   mov         eax,dword ptr [ebp-58h]
0041082A   mov         dword ptr [ebp-4Ch],eax

其它重要关键字

用一个变量去初始化 static 变量（C++）

5:        static int n = i;
00410B58   xor         eax,eax
00410B5A   mov         al,[`fun'::`2'::$S1 (0042c230)]          # 静态变量(0042c234)前面有个 (0042c230) 标记位用于标记该静态变量是否已经初始化过。 
00410B5F   and         eax,1
00410B62   test        eax,eax                                      
00410B64   jne         fun+3Eh (00410b7e)                       # 判断标记位为1，跳过初始化
00410B66   mov         cl,byte ptr [`fun'::`2'::$S1 (0042c230)]
00410B6C   or          cl,1
00410B6F   mov         byte ptr [`fun'::`2'::$S1 (0042c230)],cl # 设置标记位为1，执行初始化
00410B75   mov         edx,dword ptr [ebp+8]
00410B78   mov         dword ptr [`fun'::`2'::$S1+4 (0042c234)],edx

const

C语言

13:       const constInt = 10;
0040D464   mov         dword ptr [ebp-2Ch],0Ah
14:       temp = constInt;
0040D46B   mov         eax,dword ptr [ebp-2Ch]      # const 在C语言里本质还是一个变量
0040D46E   mov         dword ptr [ebp-24h],eax

C++

35:       const int constInt = 6;
00410C50   mov         dword ptr [ebp-50h],6
36:       temp = constInt;
00410C57   mov         dword ptr [ebp-4Ch],6        # const 在C++语言里已经变成了一个常量