还原自己写的冒泡排序
发布日期：2021-06-30 22:10:23
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分类：技术文章
本文共 8261 字，大约阅读时间需要 27 分钟。
试验
自己的源码
// hw.cpp : Defines the entry point for the console application.//#include "stdafx.h"#include#include #include #include #include #define ARY_SIZE 9void fnSortBubble(int* pAry, int nLenAry) { int i = 0; int j = 0; int iTmp = 0; for (i = 0; i < (nLenAry - 1); i++) { for (j = 0; j < (nLenAry - 1 - i); j++) { if (pAry[j] > pAry[j + 1]) { iTmp = pAry[j]; pAry[j] = pAry[j + 1]; pAry[j + 1] = iTmp; } } }}int main(int argc, char* argv[]){ int i = 0; int iAry[ARY_SIZE]; int iLenAry = sizeof(iAry) / sizeof(iAry[0]); for (i = 0; i < iLenAry; i++) { iAry[i] = rand(); } fnSortBubble(iAry, iLenAry); for (i = 0; i < iLenAry; i++) { printf("iAry[%-2d] = %d\r\n", i, iAry[i]); } /** run result iAry[0 ] = 41 iAry[1 ] = 6334 iAry[2 ] = 11478 iAry[3 ] = 15724 iAry[4 ] = 18467 iAry[5 ] = 19169 iAry[6 ] = 26500 iAry[7 ] = 26962 iAry[8 ] = 29358 请按任意键继续. . . */ system("pause"); return 0;}
IDA笔记
.text:00401000 ; =============== S U B R O U T I N E =======================================.text:00401000.text:00401000.text:00401000 ; int __cdecl fnSort(int iAryAddr, int iAryElementCnt).text:00401000 fnSort proc near ; CODE XREF: _main+22p.text:00401000.text:00401000 iAryAddr = dword ptr 4.text:00401000 iAryElementCnt = dword ptr 8.text:00401000.text:00401000 iLoopCnt = eax.text:00401000 mov iLoopCnt, [esp+iAryElementCnt].text:00401004 dec iLoopCnt ; eax = 元素个数 - 1.text:00401005 test iLoopCnt, iLoopCnt.text:00401007 jle short L_END_SORT ; 一个元素不用排序.text:00401009 push ebx.text:0040100A 精干的算法，寄存器变量的使用是非常简洁的.text:0040100A mov ebx, [esp+4+iAryAddr].text:0040100E push ebp.text:0040100F push esi.text:00401010 iLoopCntForLoop1 = edi.text:00401010 push iLoopCntForLoop1 ; save.text:00401011 mov iLoopCntForLoop1, iLoopCnt.text:00401013 _iLoopCnt = ebp.text:00401013 mov _iLoopCnt, iLoopCnt.text:00401015.text:00401015 L_LOOP1: ; CODE XREF: fnSort+33j.text:00401015 pAry = ebx.text:00401015 test iLoopCntForLoop1, iLoopCntForLoop1.text:00401017 jle short L_LOOP1_NEXT.text:00401019 pAryCur = eax.text:00401019 mov pAryCur, pAry.text:0040101B iLoopCntForLoop2 = esi.text:0040101B mov iLoopCntForLoop2, iLoopCntForLoop1.text:0040101D.text:0040101D L_LOOP2: ; CODE XREF: fnSort+2Fj.text:0040101D mov ecx, [pAryCur] ; 临时寄存器变量搞了2个: ecx, edx.text:0040101F mov edx, [pAryCur+4].text:00401022 cmp ecx, edx.text:00401024 jle short L_NOT_NEED_SORT ; i++.text:00401026 mov [pAryCur], edx ; if (pAry[i + 0] > pAry[i + 1]) { 交换数据 }.text:00401028 mov [pAryCur+4], ecx.text:0040102B.text:0040102B L_NOT_NEED_SORT: ; CODE XREF: fnSort+24j.text:0040102B add pAryCur, 4 ; i++.text:0040102E dec iLoopCntForLoop2.text:0040102F jnz short L_LOOP2 ; 临时寄存器变量搞了2个: ecx, edx.text:00401031.text:00401031 L_LOOP1_NEXT: ; CODE XREF: fnSort+17j.text:00401031 dec iLoopCntForLoop1.text:00401032 dec _iLoopCnt.text:00401033 jnz short L_LOOP1.text:00401035 pop edi ; restore.text:00401036 pop esi.text:00401037 pop ebp.text:00401038 pop ebx.text:00401039.text:00401039 L_END_SORT: ; CODE XREF: fnSort+7j.text:00401039 retn.text:00401039 fnSort endp.text:00401039.text:00401039 ; ---------------------------------------------------------------------------.text:0040103A align 10h.text:00401040.text:00401040 ; =============== S U B R O U T I N E =======================================.text:00401040.text:00401040.text:00401040 ; int __cdecl main(int argc, const char **argv, const char **envp).text:00401040 _main proc near ; CODE XREF: start+AFp.text:00401040.text:00401040 iAry_9 = byte ptr -24h.text:00401040 argc = dword ptr 4.text:00401040 argv = dword ptr 8.text:00401040 envp = dword ptr 0Ch.text:00401040.text:00401040 sub esp, 24h.text:00401043 push esi.text:00401044 push edi.text:00401045 pAry = esi.text:00401045 lea pAry, [esp+2Ch+iAry_9] ; 数组首地址.text:00401049 mov edi, 9 ; 数组元素个数 = 9.text:0040104E.text:0040104E L_INIT_ARY: ; CODE XREF: _main+19j.text:0040104E call _rand.text:00401053 mov [pAry], eax.text:00401055 add pAry, 4.text:00401058 dec edi.text:00401059 jnz short L_INIT_ARY ; 数组初始化.text:00401059 ; ;.text:0040105B lea eax, [esp+2Ch+iAry_9].text:0040105F push 9 ; iAryElementCnt.text:00401061 push eax ; iAryAddr.text:00401062 call fnSort ; 排序.text:00401067 add esp, 8.text:0040106A xor esi, esi.text:0040106C lea edi, [esp+2Ch+iAry_9] ; 数组首地址.text:00401070.text:00401070 L_LOOP_PRINT_ARY: ; CODE XREF: _main+48j.text:00401070 mov ecx, [edi].text:00401072 push ecx.text:00401073 push esi.text:00401074 push offset Format ; "iAry[%-2d] = %d\r\n".text:00401079 call _printf.text:0040107E add esp, 0Ch.text:00401081 inc esi.text:00401082 add edi, 4.text:00401085 cmp esi, 9.text:00401088 jl short L_LOOP_PRINT_ARY ; 循环打印数组.text:00401088 ; ;.text:0040108A push offset aPause ; "pause".text:0040108F call _my_system.text:00401094 add esp, 4.text:00401097 xor eax, eax.text:00401099 pop edi.text:0040109A pop esi.text:0040109B add esp, 24h.text:0040109E retn.text:0040109E _main endp.text:0040109E.text:0040109E ; --------------------------------------------------------------------------- 还原后的代码
// hw.cpp : Defines the entry point for the console application.//#include "stdafx.h"#include#include int __cdecl fnSort(int iAryAddr, int iAryElementCnt) { int iLoopCnt = iAryElementCnt; int iLoopCntCpy = iLoopCnt; int* pAry = (int*)iAryAddr; int* pAryCur = NULL; int iTmp = 0; if (--iLoopCnt <= 0) { return 0; // 一个元素不用排序 } // 最大的数经过一轮后，换到最后面去了. while (iLoopCnt > 0) { pAryCur = pAry; iLoopCntCpy = iLoopCnt; do { if (*pAryCur > *(pAryCur + 1)) { iTmp = *pAryCur; *pAryCur = *(pAryCur + 1); *(pAryCur + 1) = iTmp; } pAryCur++; } while (--iLoopCntCpy != 0); if (0 == --iLoopCnt) { break; } } return 0;}int main(int argc, char* argv[]){ int iAry_9[9]; int i = 0; // L_INIT_ARY for (i = 0; i < 9; i++) { iAry_9[i] = rand(); } fnSort((int)&iAry_9[0], 9); // L_LOOP_PRINT_ARY for (i = 0; i < 9; i++) { printf("iAry[%-2d] = %d\r\n", i, iAry_9[i]); } system("pause"); return 0;}
总结
编译器做的优化挺有意思，交换2个变量时，用了2个寄存器保存src和dst.而不是搞一个中间变量.
暂时只能做到等价还原, 在C语言层面，无法还原出原来的for循环，只能做成do-while或while。转载地址：https://lostspeed.blog.csdn.net/article/details/52506911 如侵犯您的版权，请留言回复原文章的地址，我们会给您删除此文章，给您带来不便请您谅解！
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很好
[***.229.124.182]2024年04月06日 14时28分16秒
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