mirror of
https://github.com/cuberite/libdeflate.git
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f2c3a5b4e9
* Bring in common headers and program code from xpack project * Move program code to programs/ * Move library code to lib/ * GNU89 and MSVC2010 compatibility * Other changes
79 lines
1.9 KiB
C
79 lines
1.9 KiB
C
/*
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* gzip_compress.c - compress with a gzip wrapper
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*
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* Written in 2014-2016 by Eric Biggers <ebiggers3@gmail.com>
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*
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* To the extent possible under law, the author(s) have dedicated all copyright
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* and related and neighboring rights to this software to the public domain
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* worldwide. This software is distributed without any warranty.
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*
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* You should have received a copy of the CC0 Public Domain Dedication along
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* with this software. If not, see
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* <http://creativecommons.org/publicdomain/zero/1.0/>.
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*/
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#include "crc32.h"
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#include "deflate_compress.h"
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#include "gzip_constants.h"
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#include "unaligned.h"
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#include "libdeflate.h"
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LIBEXPORT size_t
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gzip_compress(struct deflate_compressor *c, const void *in, size_t in_size,
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void *out, size_t out_nbytes_avail)
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{
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u8 *out_next = out;
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unsigned compression_level;
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u8 xfl;
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size_t deflate_size;
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if (out_nbytes_avail <= GZIP_MIN_OVERHEAD)
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return 0;
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/* ID1 */
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*out_next++ = GZIP_ID1;
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/* ID2 */
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*out_next++ = GZIP_ID2;
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/* CM */
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*out_next++ = GZIP_CM_DEFLATE;
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/* FLG */
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*out_next++ = 0;
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/* MTIME */
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put_unaligned_le32(GZIP_MTIME_UNAVAILABLE, out_next);
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out_next += 4;
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/* XFL */
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xfl = 0;
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compression_level = deflate_get_compression_level(c);
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if (compression_level < 2)
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xfl |= GZIP_XFL_FASTEST_COMRESSION;
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else if (compression_level >= 8)
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xfl |= GZIP_XFL_SLOWEST_COMRESSION;
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*out_next++ = xfl;
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/* OS */
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*out_next++ = GZIP_OS_UNKNOWN; /* OS */
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/* Compressed data */
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deflate_size = deflate_compress(c, in, in_size, out_next,
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out_nbytes_avail - GZIP_MIN_OVERHEAD);
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if (deflate_size == 0)
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return 0;
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out_next += deflate_size;
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/* CRC32 */
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put_unaligned_le32(crc32_gzip(in, in_size), out_next);
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out_next += 4;
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/* ISIZE */
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put_unaligned_le32((u32)in_size, out_next);
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out_next += 4;
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return out_next - (u8 *)out;
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}
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LIBEXPORT size_t
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gzip_compress_bound(struct deflate_compressor *c, size_t in_nbytes)
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{
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return GZIP_MIN_OVERHEAD + deflate_compress_bound(c, in_nbytes);
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}
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