pngcrush  1.8.13
About: Pngcrush is an optimizer for PNG (Portable Network Graphics) files.
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compress.c
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1 /* compress.c -- compress a memory buffer
2  * Copyright (C) 1995-2005, 2014, 2016 Jean-loup Gailly, Mark Adler
3  * For conditions of distribution and use, see copyright notice in zlib.h
4  */
5 
6 /* @(#) $Id$ */
7 
8 #define ZLIB_INTERNAL
9 #include "zlib.h"
10 
11 /* ===========================================================================
12  Compresses the source buffer into the destination buffer. The level
13  parameter has the same meaning as in deflateInit. sourceLen is the byte
14  length of the source buffer. Upon entry, destLen is the total size of the
15  destination buffer, which must be at least 0.1% larger than sourceLen plus
16  12 bytes. Upon exit, destLen is the actual size of the compressed buffer.
17 
18  compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
19  memory, Z_BUF_ERROR if there was not enough room in the output buffer,
20  Z_STREAM_ERROR if the level parameter is invalid.
21 */
22 int ZEXPORT compress2 (dest, destLen, source, sourceLen, level)
23  Bytef *dest;
24  uLongf *destLen;
25  const Bytef *source;
26  uLong sourceLen;
27  int level;
28 {
29  z_stream stream;
30  int err;
31  const uInt max = (uInt)-1;
32  uLong left;
33 
34  left = *destLen;
35  *destLen = 0;
36 
37  stream.zalloc = (alloc_func)0;
38  stream.zfree = (free_func)0;
39  stream.opaque = (voidpf)0;
40 
41  err = deflateInit(&stream, level);
42  if (err != Z_OK) return err;
43 
44  stream.next_out = dest;
45  stream.avail_out = 0;
46  stream.next_in = (z_const Bytef *)source;
47  stream.avail_in = 0;
48 
49  do {
50  if (stream.avail_out == 0) {
51  stream.avail_out = left > (uLong)max ? max : (uInt)left;
52  left -= stream.avail_out;
53  }
54  if (stream.avail_in == 0) {
55  stream.avail_in = sourceLen > (uLong)max ? max : (uInt)sourceLen;
56  sourceLen -= stream.avail_in;
57  }
58  err = deflate(&stream, sourceLen ? Z_NO_FLUSH : Z_FINISH);
59  } while (err == Z_OK);
60 
61  *destLen = stream.total_out;
62  deflateEnd(&stream);
63  return err == Z_STREAM_END ? Z_OK : err;
64 }
65 
66 /* ===========================================================================
67  */
68 int ZEXPORT compress (dest, destLen, source, sourceLen)
69  Bytef *dest;
70  uLongf *destLen;
71  const Bytef *source;
72  uLong sourceLen;
73 {
74  return compress2(dest, destLen, source, sourceLen, Z_DEFAULT_COMPRESSION);
75 }
76 
77 /* ===========================================================================
78  If the default memLevel or windowBits for deflateInit() is changed, then
79  this function needs to be updated.
80  */
82  uLong sourceLen;
83 {
84  return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
85  (sourceLen >> 25) + 13;
86 }
z_stream_s::next_in
Bytef * next_in
Definition: zlib.h:87
uLong
unsigned long uLong
Definition: zconf.h:394
deflateEnd
int deflateEnd(z_streamp strm)
Definition: deflate.c:1076
z_stream_s::zfree
free_func zfree
Definition: zlib.h:99
z_stream_s::avail_in
uInt avail_in
Definition: zlib.h:88
Z_FINISH
#define Z_FINISH
Definition: zlib.h:172
uLongf
uLong uLongf
Definition: zconf.h:405
z_stream_s::avail_out
uInt avail_out
Definition: zlib.h:92
z_const
#define z_const
Definition: zconf.h:237
Z_NO_FLUSH
#define Z_NO_FLUSH
Definition: zlib.h:168
Z_OK
#define Z_OK
Definition: zlib.h:177
voidpf
Byte * voidpf
Definition: zconf.h:413
z_stream_s::zalloc
alloc_func zalloc
Definition: zlib.h:98
Z_STREAM_END
#define Z_STREAM_END
Definition: zlib.h:178
z_stream_s
Definition: zlib.h:86
compress2
int compress2(Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen, int level)
Definition: compress.c:22
z_stream_s::next_out
Bytef * next_out
Definition: zlib.h:91
compressBound
uLong compressBound(uLong sourceLen)
Definition: compress.c:81
alloc_func
voidpf(* alloc_func)()
Definition: zlib.h:81
ZEXPORT
#define ZEXPORT
Definition: zconf.h:380
Z_DEFAULT_COMPRESSION
#define Z_DEFAULT_COMPRESSION
Definition: zlib.h:193
compress
int compress(Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen)
Definition: compress.c:68
uInt
unsigned int uInt
Definition: zconf.h:393
Bytef
Byte Bytef
Definition: zconf.h:400
deflate
int deflate(z_streamp strm, int flush)
Definition: deflate.c:763
deflateInit
#define deflateInit(strm, level)
Definition: zlib.h:1805
z_stream_s::opaque
voidpf opaque
Definition: zlib.h:100
z_stream_s::total_out
uLong total_out
Definition: zlib.h:93
zlib.h
free_func
void(* free_func)()
Definition: zlib.h:82