zlib使用教程

1. 下載zlib
   http://www.zlib.net/
   
2. 編譯zlib庫
   打開sln: zlib-1.2.11\contrib\vstudio\vc12\zlibvc.sln
   
   生成庫位置：
   zlib-1.2.11\contrib\vstudio\vc12\x86\ZlibDllRelease
   
3. 調用zlib庫
   添加lib依賴庫位置：zlibwapi.lib的文件位置
   
   添加zlibwapi.lib 在附加依賴庫中 鍵入zlibwapi.lib
   
   添加include位置：
   
   需要兩個頭文件：
   zconf.h
   zlib.h
   將其copy到一個文件夾中，然後附加到目錄即可
4. 一個例子
   一個例子：

  char text[] = "zlib compress and uncompress test\[email protected]\n2012-11-05\n";
  char de_text[1024];
  uLong tlen = strlen(text) + 1;  /* 需要把字符串的結束符'\0'也一併處理 */
  char* buf = NULL;
  uLong blen;

  /* 計算緩衝區大小，併爲其分配內存 */
  blen = compressBound(tlen); /* 壓縮後的長度是不會超過blen的 */
  if ((buf = (char*)malloc(sizeof(char) * blen)) == NULL)
  {
    printf("no enough memory!\n");
    return -1;
  }

  /* 壓縮 */
  if (compress((Bytef *)buf, &blen, (Bytef *)text, tlen) != Z_OK)
  {
    printf("compress failed!\n");
    return -1;
  }

  /* 解壓縮 */
  if (uncompress((Bytef *)de_text, &tlen, (Bytef *)buf, blen) != Z_OK)
  {
    printf("uncompress failed!\n");
    return -1;
  }

  /* 打印結果，並釋放內存 */
  printf("%s", de_text);
  if (buf != NULL)
  {
    free(buf);
    buf = NULL;
  }

  return 0;

編譯
一般會出現下面的錯誤

加入宏定義 :ZLIB_WINAPI

注意：
compress 與uncompress這兩個簡單接口中的類型轉換
編碼長度和解碼長度儘可能保證在256以下，不然容易出錯

官網上的測試代碼有些許問題，將其更爲256

#include <stdio.h>
#include <stdlib.h>
#include <windows.h>

#include "zlib.h"


void MyDoMinus64(LARGE_INTEGER *R,LARGE_INTEGER A,LARGE_INTEGER B)
{
    R->HighPart = A.HighPart - B.HighPart;
    if (A.LowPart >= B.LowPart)
        R->LowPart = A.LowPart - B.LowPart;
    else
    {
        R->LowPart = A.LowPart - B.LowPart;
        R->HighPart --;
    }
}

#ifdef _M_X64
// see http://msdn2.microsoft.com/library/twchhe95(en-us,vs.80).aspx for __rdtsc
unsigned __int64 __rdtsc(void);
void BeginCountRdtsc(LARGE_INTEGER * pbeginTime64)
{
 //   printf("rdtsc = %I64x\n",__rdtsc());
   pbeginTime64->QuadPart=__rdtsc();
}

LARGE_INTEGER GetResRdtsc(LARGE_INTEGER beginTime64,BOOL fComputeTimeQueryPerf)
{
    LARGE_INTEGER LIres;
    unsigned _int64 res=__rdtsc()-((unsigned _int64)(beginTime64.QuadPart));
    LIres.QuadPart=res;
   // printf("rdtsc = %I64x\n",__rdtsc());
    return LIres;
}
#else
#ifdef _M_IX86
void myGetRDTSC32(LARGE_INTEGER * pbeginTime64)
{
    DWORD dwEdx,dwEax;
    _asm
    {
        rdtsc
        mov dwEax,eax
        mov dwEdx,edx
    }
    pbeginTime64->LowPart=dwEax;
    pbeginTime64->HighPart=dwEdx;
}

void BeginCountRdtsc(LARGE_INTEGER * pbeginTime64)
{
    myGetRDTSC32(pbeginTime64);
}

LARGE_INTEGER GetResRdtsc(LARGE_INTEGER beginTime64,BOOL fComputeTimeQueryPerf)
{
    LARGE_INTEGER LIres,endTime64;
    myGetRDTSC32(&endTime64);

    LIres.LowPart=LIres.HighPart=0;
    MyDoMinus64(&LIres,endTime64,beginTime64);
    return LIres;
}
#else
void myGetRDTSC32(LARGE_INTEGER * pbeginTime64)
{
}

void BeginCountRdtsc(LARGE_INTEGER * pbeginTime64)
{
}

LARGE_INTEGER GetResRdtsc(LARGE_INTEGER beginTime64,BOOL fComputeTimeQueryPerf)
{
    LARGE_INTEGER lr;
    lr.QuadPart=0;
    return lr;
}
#endif
#endif

void BeginCountPerfCounter(LARGE_INTEGER * pbeginTime64,BOOL fComputeTimeQueryPerf)
{
    if ((!fComputeTimeQueryPerf) || (!QueryPerformanceCounter(pbeginTime64)))
    {
        pbeginTime64->LowPart = GetTickCount();
        pbeginTime64->HighPart = 0;
    }
}

DWORD GetMsecSincePerfCounter(LARGE_INTEGER beginTime64,BOOL fComputeTimeQueryPerf)
{
    LARGE_INTEGER endTime64,ticksPerSecond,ticks;
    DWORDLONG ticksShifted,tickSecShifted;
    DWORD dwLog=16+0;
    DWORD dwRet;
    if ((!fComputeTimeQueryPerf) || (!QueryPerformanceCounter(&endTime64)))
        dwRet = (GetTickCount() - beginTime64.LowPart)*1;
    else
    {
        MyDoMinus64(&ticks,endTime64,beginTime64);
        QueryPerformanceFrequency(&ticksPerSecond);


        {
            ticksShifted = Int64ShrlMod32(*(DWORDLONG*)&ticks,dwLog);
            tickSecShifted = Int64ShrlMod32(*(DWORDLONG*)&ticksPerSecond,dwLog);

        }

        dwRet = (DWORD)((((DWORD)ticksShifted)*1000)/(DWORD)(tickSecShifted));
        dwRet *=1;
    }
    return dwRet;
}

int ReadFileMemory(const char* filename,long* plFileSize,unsigned char** pFilePtr)
{
    FILE* stream;
    unsigned char* ptr;
    int retVal=1;
    stream=fopen(filename, "rb");
    if (stream==NULL)
        return 0;

    fseek(stream,0,SEEK_END);

    *plFileSize=ftell(stream);
    fseek(stream,0,SEEK_SET);
    ptr=malloc((*plFileSize)+1);
    if (ptr==NULL)
        retVal=0;
    else
    {
        if (fread(ptr, 1, *plFileSize,stream) != (*plFileSize))
            retVal=0;
    }
    fclose(stream);
    *pFilePtr=ptr;
    return retVal;
}

int main(int argc, char *argv[])
{
    int BlockSizeCompress=256;
    int BlockSizeUncompress = 256;//0x8000; 注意需爲256
    int cprLevel=Z_DEFAULT_COMPRESSION ;
    long lFileSize;
    unsigned char* FilePtr;
    long lBufferSizeCpr;
    long lBufferSizeUncpr;
    long lCompressedSize=0;
    unsigned char* CprPtr;
    unsigned char* UncprPtr;
    long lSizeCpr,lSizeUncpr;
    DWORD dwGetTick,dwMsecQP;
    LARGE_INTEGER li_qp,li_rdtsc,dwResRdtsc;

    if (argc<=1)
    {
        printf("run TestZlib <File> [BlockSizeCompress] [BlockSizeUncompress] [compres. level]\n");
        return 0;
    }

    if (ReadFileMemory(argv[1],&lFileSize,&FilePtr)==0)
    {
        printf("error reading %s\n",argv[1]);
        return 1;
    }
    else printf("file %s read, %u bytes\n",argv[1],lFileSize);

    if (argc>=3)
        BlockSizeCompress=atol(argv[2]);

    if (argc>=4)
        BlockSizeUncompress=atol(argv[3]);

    if (argc>=5)
        cprLevel=(int)atol(argv[4]);

    lBufferSizeCpr = lFileSize + (lFileSize/0x10) + 0x200;
    lBufferSizeUncpr = lBufferSizeCpr;

    CprPtr=(unsigned char*)malloc(lBufferSizeCpr + BlockSizeCompress);

    BeginCountPerfCounter(&li_qp,TRUE);
    dwGetTick=GetTickCount();
    BeginCountRdtsc(&li_rdtsc);
    {
        z_stream zcpr;
        int ret=Z_OK;
        long lOrigToDo = lFileSize;
        long lOrigDone = 0;
        int step=0;
        memset(&zcpr,0,sizeof(z_stream));
        deflateInit(&zcpr,cprLevel);

        zcpr.next_in = FilePtr;
        zcpr.next_out = CprPtr;


        do
        {
            long all_read_before = zcpr.total_in;
            zcpr.avail_in = min(lOrigToDo,BlockSizeCompress);
            zcpr.avail_out = BlockSizeCompress;
            ret=deflate(&zcpr,(zcpr.avail_in==lOrigToDo) ? Z_FINISH : Z_SYNC_FLUSH);
            lOrigDone += (zcpr.total_in-all_read_before);
            lOrigToDo -= (zcpr.total_in-all_read_before);
            step++;
        } while (ret==Z_OK);

        lSizeCpr=zcpr.total_out;
        deflateEnd(&zcpr);
        dwGetTick=GetTickCount()-dwGetTick;
        dwMsecQP=GetMsecSincePerfCounter(li_qp,TRUE);
        dwResRdtsc=GetResRdtsc(li_rdtsc,TRUE);
        printf("total compress size = %u, in %u step\n",lSizeCpr,step);
        printf("time = %u msec = %f sec\n",dwGetTick,dwGetTick/(double)1000.);
        printf("defcpr time QP = %u msec = %f sec\n",dwMsecQP,dwMsecQP/(double)1000.);
        printf("defcpr result rdtsc = %I64x\n\n",dwResRdtsc.QuadPart);
    }

    CprPtr=(unsigned char*)realloc(CprPtr,lSizeCpr);
    UncprPtr=(unsigned char*)malloc(lBufferSizeUncpr + BlockSizeUncompress);

    BeginCountPerfCounter(&li_qp,TRUE);
    dwGetTick=GetTickCount();
    BeginCountRdtsc(&li_rdtsc);
    {
        z_stream zcpr;
        int ret=Z_OK;
        long lOrigToDo = lSizeCpr;
        long lOrigDone = 0;
        int step=0;
        memset(&zcpr,0,sizeof(z_stream));
        inflateInit(&zcpr);

        zcpr.next_in = CprPtr;
        zcpr.next_out = UncprPtr;


        do
        {
            long all_read_before = zcpr.total_in;
            zcpr.avail_in = min(lOrigToDo,BlockSizeUncompress);
            zcpr.avail_out = BlockSizeUncompress;
            ret=inflate(&zcpr,Z_SYNC_FLUSH);
            lOrigDone += (zcpr.total_in-all_read_before);
            lOrigToDo -= (zcpr.total_in-all_read_before);
            step++;
        } while (ret==Z_OK);

        lSizeUncpr=zcpr.total_out;
        inflateEnd(&zcpr);
        dwGetTick=GetTickCount()-dwGetTick;
        dwMsecQP=GetMsecSincePerfCounter(li_qp,TRUE);
        dwResRdtsc=GetResRdtsc(li_rdtsc,TRUE);
        printf("total uncompress size = %u, in %u step\n",lSizeUncpr,step);
        printf("time = %u msec = %f sec\n",dwGetTick,dwGetTick/(double)1000.);
        printf("uncpr  time QP = %u msec = %f sec\n",dwMsecQP,dwMsecQP/(double)1000.);
        printf("uncpr  result rdtsc = %I64x\n\n",dwResRdtsc.QuadPart);
    }

    if (lSizeUncpr==lFileSize)
    {
        if (memcmp(FilePtr,UncprPtr,lFileSize)==0)
            printf("compare ok\n");

    }

    return 0;
}

這裏，zlib只是把一段內存壓縮，壓縮後放的另一段內存上，這離壓縮文件甚至文件夾的目標還很遠

zlib介紹
zlib是提供數據壓縮用的函式庫，由Jean-loup Gailly與Mark Adler所開發，初版0.9版在1995年5月1日發表。zlib使用DEFLATE算法，最初是爲libpng函式庫所寫的，後來普遍爲許多軟件所使用。此函式庫爲自由軟件，使用zlib授權
參考資料
CSDN博客(http://blog.csdn.net/JasonDing1354/article/details/42676685)
http://blog.csdn.net/gubenpeiyuan/article/details/8734290