compress.cpp

DES,MD5,ZLIB算法源代码

#include "stdafx.h"
#include "zlib.h"

/* ===========================================================================
     Compresses the source buffer into the destination buffer. The level
   parameter has the same meaning as in deflateInit.  sourceLen is the byte
   length of the source buffer. Upon entry, destLen is the total size of the
   destination buffer, which must be at least 0.1% larger than sourceLen plus
   12 bytes. Upon exit, destLen is the actual size of the compressed buffer.

     compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
   memory, Z_BUF_ERROR if there was not enough room in the output buffer,
   Z_STREAM_ERROR if the level parameter is invalid.
*/
int compress2(BYTE *dest,  
			  unsigned long *destLen,  
			  const BYTE *source,
			  unsigned long sourceLen,
			  int level)
{
    z_stream stream;
    int err;

    stream.next_in = (BYTE*)source;
    stream.avail_in = (unsigned int)sourceLen;
    stream.next_out = dest;
    stream.avail_out = (unsigned int)*destLen;
    if ((unsigned long)stream.avail_out != *destLen) return Z_BUF_ERROR;

    stream.zalloc = (alloc_func)0;
    stream.zfree = (free_func)0;
    stream.opaque = (void *)0;

    err = deflateInit(&stream, level);
    if (err != Z_OK) return err;

    err = deflate(&stream, Z_FINISH);
    if (err != Z_STREAM_END) {
        deflateEnd(&stream);
        return err == Z_OK ? Z_BUF_ERROR : err;
    }
    *destLen = stream.total_out;

    err = deflateEnd(&stream);
    return err;
}

/* ===========================================================================
 */
ARITHDLL_API int WINAPI compress (BYTE *dest,
    unsigned long *destLen,
    const BYTE *source,
    unsigned long sourceLen)
{
    return compress2(dest, destLen, source, sourceLen, Z_DEFAULT_COMPRESSION);
}

/*===========================================================================
     Decompresses the source buffer into the destination buffer.  sourceLen is
   the byte length of the source buffer. Upon entry, destLen is the total
   size of the destination buffer, which must be large enough to hold the
   entire uncompressed data. (The size of the uncompressed data must have
   been saved previously by the compressor and transmitted to the decompressor
   by some mechanism outside the scope of this compression library.)
   Upon exit, destLen is the actual size of the compressed buffer.
     This function can be used to decompress a whole file at once if the
   input file is mmap'ed.

     unzipcompress returns Z_OK if success, Z_MEM_ERROR if there was not
   enough memory, Z_BUF_ERROR if there was not enough room in the output
   buffer, or Z_DATA_ERROR if the input data was corrupted.
*/
ARITHDLL_API int WINAPI uncompress (BYTE *dest, unsigned long *destLen,
            const BYTE *source, unsigned long sourceLen)
{
    z_stream stream;
    int err;

    stream.next_in = (BYTE*)source;
    stream.avail_in = (unsigned int)sourceLen;
    /* Check for source > 64K on 16-bit machine: */
    if ((unsigned long)stream.avail_in != sourceLen) return Z_BUF_ERROR;

    stream.next_out = dest;
    stream.avail_out = (unsigned int)*destLen;
    if ((unsigned long)stream.avail_out != *destLen) return Z_BUF_ERROR;

    stream.zalloc = (alloc_func)0;
    stream.zfree = (free_func)0;

    err = inflateInit(&stream);
    if (err != Z_OK) return err;

    err = inflate(&stream, Z_FINISH);
    if (err != Z_STREAM_END)
    {
        inflateEnd(&stream);
        return err == Z_OK ? Z_BUF_ERROR : err;
    }
    *destLen = stream.total_out;
    err = inflateEnd(&stream);
    return err;
}