作者：风影残烛
在还原代码的过程中。目前程序是采用VS2005(以上版本)写的。
我使用的是vc6.0，结果。在运算的时候。发现编译器对
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// FpuTlxTest.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include <string.h>#include <math.h>#include <stdlib.h>void
KeyFun(char* pComputerName){ char
szKey[16] = {0}; int
iNum_ebx = 0; int
iNum_ecx = 0; int
iNum_var30 = 0; int
dwCptNameLen = strlen(pComputerName); if
(dwCptNameLen != 0) { int
i = 1; int
iTempMod; if
(dwCptNameLen >= i) { double
dblNum = 0.0; char* pTial = &pComputerName[dwCptNameLen - 1]; int
iNum = 2; iNum = 2 - (int)pComputerName; for
(; i <= dwCptNameLen; i++, pTial--) { int
iCharacter = (int)pComputerName[i-1]; double
dblTemp = sqrt((double)iCharacter) * i + 1.0; iCharacter = iCharacter * i * i; iTempMod = (int)(dblTemp * (double)iCharacter + dblNum) % 100000; iCharacter = iTempMod; dblNum = (double)iCharacter; iCharacter = (int)*pTial; dblTemp = pow(sqrt((double)iCharacter), 2) * dblNum; iCharacter = iNum + (int)&pComputerName[i-1]; int
iTemp = (int)(dblTemp * (double)iCharacter) % 100000; iNum_ebx = iNum_ebx + iTemp + 1; iCharacter = iNum_ebx * iTempMod; iTemp = iCharacter; iCharacter = iNum_var30 - (iNum_var30 / 100000 * 100000); iNum_var30 = (int)(sqrt((double)iTemp) + (double)iCharacter); // 这里会有浮点溢出的情况 } iNum_ecx = iNum_var30; } int
iSaveNum = iTempMod + 0x1f; iSaveNum &= 0x8000007F; if
( iSaveNum < 0) { iSaveNum--; iSaveNum |= 0xFFFFFF80; iSaveNum++; } szKey[0] = (char)iSaveNum; iSaveNum = iTempMod + 0x20; iSaveNum &= 0x8000007F; if
(iSaveNum < 0) { iSaveNum--; iSaveNum |= 0xFFFFFF80; iSaveNum++; } szKey[1] = (char)iSaveNum; iSaveNum = iTempMod + 0x27; iSaveNum &= 0x8000007F; if
(iSaveNum < 0) { iSaveNum--; iSaveNum |= 0xFFFFFF80; iSaveNum++; } szKey[2] = (char)iSaveNum; iSaveNum = iTempMod + 0x3a; iSaveNum &= 0x8000007F; if
(iSaveNum < 0) { iSaveNum--; iSaveNum |= 0xFFFFFF80; iSaveNum++; } szKey[3] = (char)iSaveNum; iSaveNum = iTempMod + 0x5f; iSaveNum &= 0x8000007F; if
(iSaveNum < 0) { iSaveNum--; iSaveNum |= 0xFFFFFF80; iSaveNum++; } szKey[4] = (char)iSaveNum; iSaveNum = iNum_ebx + 0x9c; iSaveNum &= 0x8000007F; if
(iSaveNum < 0) { iSaveNum--; iSaveNum |= 0xFFFFFF80; iSaveNum++; } szKey[5] = (char)iSaveNum; iSaveNum = iNum_ebx + 0xf7; iSaveNum &= 0x8000007F; if
(iSaveNum < 0) { iSaveNum--; iSaveNum |= 0xFFFFFF80; iSaveNum++; } szKey[6] = (char)iSaveNum; iSaveNum = iNum_ebx + 0x176; iSaveNum &= 0x8000007F; if
(iSaveNum < 0) { iSaveNum--; iSaveNum |= 0xFFFFFF80; iSaveNum++; } szKey[7] = (char)iSaveNum; iSaveNum = iNum_ebx + 0x21f; iSaveNum &= 0x8000007F; if
(iSaveNum < 0) { iSaveNum--; iSaveNum |= 0xFFFFFF80; iSaveNum++; } szKey[8] = (char)iSaveNum; iSaveNum = iNum_ebx + 0x2f8; iSaveNum &= 0x8000007F; if
(iSaveNum < 0) { iSaveNum--; iSaveNum |= 0xFFFFFF80; iSaveNum++; } szKey[9] = (char)iSaveNum; iSaveNum = iNum_ecx + 0x407; iSaveNum &= 0x8000007F; if
(iSaveNum < 0) { iSaveNum--; iSaveNum |= 0xFFFFFF80; iSaveNum++; } szKey[10] = (char)iSaveNum; iSaveNum = iNum_ecx + 0x552; iSaveNum &= 0x8000007F; if
(iSaveNum < 0) { iSaveNum--; iSaveNum |= 0xFFFFFF80; iSaveNum++; } szKey[11] = (char)iSaveNum; iSaveNum = iNum_ecx + 0x6df; iSaveNum &= 0x8000007F; if
(iSaveNum < 0) { iSaveNum--; iSaveNum |= 0xFFFFFF80; iSaveNum++; } szKey[12] = (char)iSaveNum; iSaveNum = iNum_ecx + 0x8b4; iSaveNum &= 0x8000007F; if
(iSaveNum < 0) { iSaveNum--; iSaveNum |= 0xFFFFFF80; iSaveNum++; } szKey[13] = (char)iSaveNum; iNum_ecx += 0xad7; iNum_ecx &= 0x8000007F; if
(iNum_ecx < 0) { iNum_ecx--; iNum_ecx |= 0xFFFFFF80; iNum_ecx++; } szKey[14] = (char)iNum_ecx; szKey[15] = ‘\0‘; int
j = 0; int
k = 0; while
(k < 0x69) { char
ch = szKey[j]; if
(ch >= ‘0‘
&& ch <= ‘9‘) { k = k + 7; j++; } else
if (ch >= ‘A‘
&& ch <= ‘Z‘) { k = k + 7; j++; } else
if (ch >= ‘a‘
&& ch <= ‘z‘) { k = k + 7; j++; } else { int
iTemp = ch + k + 0x1f; iTemp = iTemp & 0x8000007F; if
(iTemp < 0) { iTemp--; iTemp |= 0xFFFFFF80; iTemp++; } szKey[j] = (char)iTemp; } } } printf("%s\r\n", szKey);}int
_tmain(int
argc, _TCHAR* argv[]){ KeyFun("TEN-OLOIZ"); system("pause"); return
0;} |
代码中标注的地方 。采用不同的对待方式。导致结果不一样。
vc6.0中测试：如果溢出。则放到edx、eax返回为__int64。然而代码中的为int，所以只取低32字节。
vs2005中测试：如果溢出。则正确返回。
区别在于取整库函数的是实现不一样。有兴趣的朋友可以自己跟进去看。
VC和VS系列(2005)编译器对双精度浮点溢出的处理,布布扣,bubuko.com
原文：http://www.cnblogs.com/ziolo/p/3662167.html