Libav
adler32.c
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1 /*
2  * Compute the Adler-32 checksum of a data stream.
3  * This is a modified version based on adler32.c from the zlib library.
4  *
5  * Copyright (C) 1995 Mark Adler
6  *
7  * This software is provided 'as-is', without any express or implied
8  * warranty. In no event will the authors be held liable for any damages
9  * arising from the use of this software.
10  *
11  * Permission is granted to anyone to use this software for any purpose,
12  * including commercial applications, and to alter it and redistribute it
13  * freely, subject to the following restrictions:
14  *
15  * 1. The origin of this software must not be misrepresented; you must not
16  * claim that you wrote the original software. If you use this software
17  * in a product, an acknowledgment in the product documentation would be
18  * appreciated but is not required.
19  * 2. Altered source versions must be plainly marked as such, and must not be
20  * misrepresented as being the original software.
21  * 3. This notice may not be removed or altered from any source distribution.
22  */
23 
33 #include "config.h"
34 #include "adler32.h"
35 
36 #define BASE 65521L /* largest prime smaller than 65536 */
37 
38 #define DO1(buf) { s1 += *buf++; s2 += s1; }
39 #define DO4(buf) DO1(buf); DO1(buf); DO1(buf); DO1(buf);
40 #define DO16(buf) DO4(buf); DO4(buf); DO4(buf); DO4(buf);
41 
42 unsigned long av_adler32_update(unsigned long adler, const uint8_t * buf,
43  unsigned int len)
44 {
45  unsigned long s1 = adler & 0xffff;
46  unsigned long s2 = adler >> 16;
47 
48  while (len > 0) {
49 #if CONFIG_SMALL
50  while (len > 4 && s2 < (1U << 31)) {
51  DO4(buf);
52  len -= 4;
53  }
54 #else
55  while (len > 16 && s2 < (1U << 31)) {
56  DO16(buf);
57  len -= 16;
58  }
59 #endif
60  DO1(buf); len--;
61  s1 %= BASE;
62  s2 %= BASE;
63  }
64  return (s2 << 16) | s1;
65 }
66 
67 #ifdef TEST
68 #include <string.h>
69 #include "log.h"
70 #include "timer.h"
71 #define LEN 7001
72 
73 static volatile int checksum;
74 
75 int main(int argc, char **argv)
76 {
77  int i;
78  char data[LEN];
79 
81 
82  for (i = 0; i < LEN; i++)
83  data[i] = ((i * i) >> 3) + 123 * i;
84 
85  if (argc > 1 && !strcmp(argv[1], "-t")) {
86  for (i = 0; i < 1000; i++) {
88  checksum = av_adler32_update(1, data, LEN);
89  STOP_TIMER("adler");
90  }
91  } else {
92  checksum = av_adler32_update(1, data, LEN);
93  }
94 
95  av_log(NULL, AV_LOG_DEBUG, "%X (expected 50E6E508)\n", checksum);
96  return checksum == 0x50e6e508 ? 0 : 1;
97 }
98 #endif
#define DO16(buf)
Definition: adler32.c:40
void av_log_set_level(int level)
Set the log level.
Definition: log.c:190
#define BASE
Definition: adler32.c:36
Public header for libavutil Adler32 hasher.
void av_log(void *avcl, int level, const char *fmt,...) av_printf_format(3
Send the specified message to the log if the level is less than or equal to the current av_log_level...
uint8_t
#define DO4(buf)
Definition: adler32.c:39
unsigned long av_adler32_update(unsigned long adler, const uint8_t *buf, unsigned int len)
Calculate the Adler32 checksum of a buffer.
Definition: adler32.c:42
const char data[16]
Definition: mxf.c:70
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:144
int main(int argc, char **argv)
Definition: avconv.c:2608
NULL
Definition: eval.c:55
#define START_TIMER
Definition: timer.h:84
#define DO1(buf)
Definition: adler32.c:38
#define STOP_TIMER(id)
Definition: timer.h:85
Definition: vf_drawbox.c:37
int len