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75 lines
2.6 KiB
C
75 lines
2.6 KiB
C
/* compress.c -- compress a memory buffer
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* Copyright (C) 1995-2005, 2014 Jean-loup Gailly, Mark Adler.
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* For conditions of distribution and use, see copyright notice in zlib.h
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*/
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/* @(#) $Id$ */
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#define ZLIB_INTERNAL
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#include "zlib.h"
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/* ===========================================================================
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Compresses the source buffer into the destination buffer. The level
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parameter has the same meaning as in deflateInit. sourceLen is the byte
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length of the source buffer. Upon entry, destLen is the total size of the
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destination buffer, which must be at least 0.1% larger than sourceLen plus
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12 bytes. Upon exit, destLen is the actual size of the compressed buffer.
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compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
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memory, Z_BUF_ERROR if there was not enough room in the output buffer,
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Z_STREAM_ERROR if the level parameter is invalid.
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*/
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int ZEXPORT compress2(unsigned char *dest, size_t *destLen, const unsigned char *source,
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size_t sourceLen, int level) {
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z_stream stream;
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int err;
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const unsigned int max = (unsigned int)0 - 1;
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size_t left;
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left = *destLen;
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*destLen = 0;
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stream.zalloc = (alloc_func)0;
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stream.zfree = (free_func)0;
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stream.opaque = NULL;
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err = deflateInit(&stream, level);
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if (err != Z_OK)
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return err;
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stream.next_out = dest;
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stream.avail_out = 0;
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stream.next_in = (const unsigned char *)source;
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stream.avail_in = 0;
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do {
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if (stream.avail_out == 0) {
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stream.avail_out = left > (unsigned long)max ? max : (unsigned int)left;
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left -= stream.avail_out;
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}
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if (stream.avail_in == 0) {
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stream.avail_in = sourceLen > (unsigned long)max ? max : (unsigned int)sourceLen;
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sourceLen -= stream.avail_in;
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}
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err = deflate(&stream, sourceLen ? Z_NO_FLUSH : Z_FINISH);
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} while (err == Z_OK);
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*destLen = stream.total_out;
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deflateEnd(&stream);
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return err == Z_STREAM_END ? Z_OK : err;
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}
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/* ===========================================================================
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*/
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int ZEXPORT compress(unsigned char *dest, size_t *destLen, const unsigned char *source, size_t sourceLen) {
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return compress2(dest, destLen, source, sourceLen, Z_DEFAULT_COMPRESSION);
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}
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/* ===========================================================================
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If the default memLevel or windowBits for deflateInit() is changed, then
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this function needs to be updated.
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*/
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size_t ZEXPORT compressBound(size_t sourceLen) {
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return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + (sourceLen >> 25) + 13;
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}
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