compress.c
上传用户:romrleung
上传日期:2022-05-23
资源大小:18897k
文件大小:2k
- /* compress.c -- compress a memory buffer
- * Copyright (C) 1995-2003 Jean-loup Gailly.
- * For conditions of distribution and use, see copyright notice in zlib.h
- */
- /* @(#) $Id$ */
- #define ZLIB_INTERNAL
- #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 ZEXPORT compress2 (dest, destLen, source, sourceLen, level)
- Bytef *dest;
- uLongf *destLen;
- const Bytef *source;
- uLong sourceLen;
- int level;
- {
- z_stream stream;
- int err;
- stream.next_in = (Bytef*)source;
- stream.avail_in = (uInt)sourceLen;
- #ifdef MAXSEG_64K
- /* Check for source > 64K on 16-bit machine: */
- if ((uLong)stream.avail_in != sourceLen) return Z_BUF_ERROR;
- #endif
- stream.next_out = dest;
- stream.avail_out = (uInt)*destLen;
- if ((uLong)stream.avail_out != *destLen) return Z_BUF_ERROR;
- stream.zalloc = (alloc_func)0;
- stream.zfree = (free_func)0;
- stream.opaque = (voidpf)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;
- }
- /* ===========================================================================
- */
- int ZEXPORT compress (dest, destLen, source, sourceLen)
- Bytef *dest;
- uLongf *destLen;
- const Bytef *source;
- uLong sourceLen;
- {
- return compress2(dest, destLen, source, sourceLen, Z_DEFAULT_COMPRESSION);
- }
- /* ===========================================================================
- If the default memLevel or windowBits for deflateInit() is changed, then
- this function needs to be updated.
- */
- uLong ZEXPORT compressBound (sourceLen)
- uLong sourceLen;
- {
- return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + 11;
- }