mirror of
https://github.com/cuberite/libdeflate.git
synced 2025-08-04 10:16:44 -04:00
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
71 lines
1.9 KiB
C
71 lines
1.9 KiB
C
/*
|
|
* zlib_compress.c - compress with a zlib wrapper
|
|
*
|
|
* Written in 2014-2016 by Eric Biggers <ebiggers3@gmail.com>
|
|
*
|
|
* To the extent possible under law, the author(s) have dedicated all copyright
|
|
* and related and neighboring rights to this software to the public domain
|
|
* worldwide. This software is distributed without any warranty.
|
|
*
|
|
* You should have received a copy of the CC0 Public Domain Dedication along
|
|
* with this software. If not, see
|
|
* <http://creativecommons.org/publicdomain/zero/1.0/>.
|
|
*/
|
|
|
|
#include "adler32.h"
|
|
#include "deflate_compress.h"
|
|
#include "unaligned.h"
|
|
#include "zlib_constants.h"
|
|
|
|
#include "libdeflate.h"
|
|
|
|
LIBEXPORT size_t
|
|
zlib_compress(struct deflate_compressor *c, const void *in, size_t in_size,
|
|
void *out, size_t out_nbytes_avail)
|
|
{
|
|
u8 *out_next = out;
|
|
u16 hdr;
|
|
unsigned compression_level;
|
|
unsigned level_hint;
|
|
size_t deflate_size;
|
|
|
|
if (out_nbytes_avail <= ZLIB_MIN_OVERHEAD)
|
|
return 0;
|
|
|
|
/* 2 byte header: CMF and FLG */
|
|
hdr = (ZLIB_CM_DEFLATE << 8) | (ZLIB_CINFO_32K_WINDOW << 12);
|
|
compression_level = deflate_get_compression_level(c);
|
|
if (compression_level < 2)
|
|
level_hint = ZLIB_FASTEST_COMPRESSION;
|
|
else if (compression_level < 6)
|
|
level_hint = ZLIB_FAST_COMPRESSION;
|
|
else if (compression_level < 8)
|
|
level_hint = ZLIB_DEFAULT_COMPRESSION;
|
|
else
|
|
level_hint = ZLIB_SLOWEST_COMPRESSION;
|
|
hdr |= level_hint << 6;
|
|
hdr |= 31 - (hdr % 31);
|
|
|
|
put_unaligned_be16(hdr, out_next);
|
|
out_next += 2;
|
|
|
|
/* Compressed data */
|
|
deflate_size = deflate_compress(c, in, in_size, out_next,
|
|
out_nbytes_avail - ZLIB_MIN_OVERHEAD);
|
|
if (deflate_size == 0)
|
|
return 0;
|
|
out_next += deflate_size;
|
|
|
|
/* ADLER32 */
|
|
put_unaligned_be32(adler32(in, in_size), out_next);
|
|
out_next += 4;
|
|
|
|
return out_next - (u8 *)out;
|
|
}
|
|
|
|
LIBEXPORT size_t
|
|
zlib_compress_bound(struct deflate_compressor *c, size_t in_nbytes)
|
|
{
|
|
return ZLIB_MIN_OVERHEAD + deflate_compress_bound(c, in_nbytes);
|
|
}
|