Add core option: PSX cpu clock (dynarec)
[pcsx_rearmed.git] / deps / adler32.c
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7795edd6
JAS
1/* adler32.c -- compute the Adler-32 checksum of a data stream
2 * Copyright (C) 1995-2003 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 <stdint.h>
10#include <stddef.h>
11#include "zutil.h"
12
13#define BASE 65521UL /* largest prime smaller than 65536 */
14#define NMAX 5552
15/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
16
17#define DO1(buf,i) {s1 += buf[i]; s2 += s1;}
18#define DO2(buf,i) DO1(buf,i); DO1(buf,i+1);
19#define DO4(buf,i) DO2(buf,i); DO2(buf,i+2);
20#define DO8(buf,i) DO4(buf,i); DO4(buf,i+4);
21#define DO16(buf) DO8(buf,0); DO8(buf,8);
22
23#ifdef NO_DIVIDE
24# define MOD(a) \
25 do { \
26 if (a >= (BASE << 16)) a -= (BASE << 16); \
27 if (a >= (BASE << 15)) a -= (BASE << 15); \
28 if (a >= (BASE << 14)) a -= (BASE << 14); \
29 if (a >= (BASE << 13)) a -= (BASE << 13); \
30 if (a >= (BASE << 12)) a -= (BASE << 12); \
31 if (a >= (BASE << 11)) a -= (BASE << 11); \
32 if (a >= (BASE << 10)) a -= (BASE << 10); \
33 if (a >= (BASE << 9)) a -= (BASE << 9); \
34 if (a >= (BASE << 8)) a -= (BASE << 8); \
35 if (a >= (BASE << 7)) a -= (BASE << 7); \
36 if (a >= (BASE << 6)) a -= (BASE << 6); \
37 if (a >= (BASE << 5)) a -= (BASE << 5); \
38 if (a >= (BASE << 4)) a -= (BASE << 4); \
39 if (a >= (BASE << 3)) a -= (BASE << 3); \
40 if (a >= (BASE << 2)) a -= (BASE << 2); \
41 if (a >= (BASE << 1)) a -= (BASE << 1); \
42 if (a >= BASE) a -= BASE; \
43 } while (0)
44#else
45# define MOD(a) a %= BASE
46#endif
47
48/* ========================================================================= */
49uLong adler32(uLong adler, const Bytef *buf, uInt len)
50{
51 uint32_t s1 = adler & 0xffff;
52 uint32_t s2 = (adler >> 16) & 0xffff;
53 int k;
54
55 if (buf == NULL)
56 return 1L;
57
58 while (len > 0) {
59 k = len < NMAX ? (int)len : NMAX;
60 len -= k;
61 while (k >= 16) {
62 DO16(buf);
63 buf += 16;
64 k -= 16;
65 }
66 if (k != 0) do {
67 s1 += *buf++;
68 s2 += s1;
69 } while (--k);
70 MOD(s1);
71 MOD(s2);
72 }
73 return (s2 << 16) | s1;
74}
75