Root/
Source at commit 1158 created 13 years 16 days ago. By azimutz, Match nvidia.c with the one on my branch (Chazi) adding dev id's from issue 99 and Asus G74SX (0DF4, 1251). | |
---|---|
1 | /* adler32.c -- compute the Adler-32 checksum of a data stream␊ |
2 | * Copyright (C) 1995-2007 Mark Adler␊ |
3 | * For conditions of distribution and use, see copyright notice in zlib.h␊ |
4 | */␊ |
5 | ␊ |
6 | /* @(#) $Id$ */␊ |
7 | ␊ |
8 | #include "zutil.h"␊ |
9 | ␊ |
10 | #define local static␊ |
11 | ␊ |
12 | local uLong adler32_combine_(uLong adler1, uLong adler2, z_off64_t len2);␊ |
13 | ␊ |
14 | #define BASE 65521UL /* largest prime smaller than 65536 */␊ |
15 | #define NMAX 5552␊ |
16 | /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */␊ |
17 | ␊ |
18 | #define DO1(buf,i) {adler += (buf)[i]; sum2 += adler;}␊ |
19 | #define DO2(buf,i) DO1(buf,i); DO1(buf,i+1);␊ |
20 | #define DO4(buf,i) DO2(buf,i); DO2(buf,i+2);␊ |
21 | #define DO8(buf,i) DO4(buf,i); DO4(buf,i+4);␊ |
22 | #define DO16(buf) DO8(buf,0); DO8(buf,8);␊ |
23 | ␊ |
24 | /* use NO_DIVIDE if your processor does not do division in hardware */␊ |
25 | #ifdef NO_DIVIDE␊ |
26 | # define MOD(a) \␊ |
27 | do { \␊ |
28 | if (a >= (BASE << 16)) a -= (BASE << 16); \␊ |
29 | if (a >= (BASE << 15)) a -= (BASE << 15); \␊ |
30 | if (a >= (BASE << 14)) a -= (BASE << 14); \␊ |
31 | if (a >= (BASE << 13)) a -= (BASE << 13); \␊ |
32 | if (a >= (BASE << 12)) a -= (BASE << 12); \␊ |
33 | if (a >= (BASE << 11)) a -= (BASE << 11); \␊ |
34 | if (a >= (BASE << 10)) a -= (BASE << 10); \␊ |
35 | if (a >= (BASE << 9)) a -= (BASE << 9); \␊ |
36 | if (a >= (BASE << 8)) a -= (BASE << 8); \␊ |
37 | if (a >= (BASE << 7)) a -= (BASE << 7); \␊ |
38 | if (a >= (BASE << 6)) a -= (BASE << 6); \␊ |
39 | if (a >= (BASE << 5)) a -= (BASE << 5); \␊ |
40 | if (a >= (BASE << 4)) a -= (BASE << 4); \␊ |
41 | if (a >= (BASE << 3)) a -= (BASE << 3); \␊ |
42 | if (a >= (BASE << 2)) a -= (BASE << 2); \␊ |
43 | if (a >= (BASE << 1)) a -= (BASE << 1); \␊ |
44 | if (a >= BASE) a -= BASE; \␊ |
45 | } while (0)␊ |
46 | # define MOD4(a) \␊ |
47 | do { \␊ |
48 | if (a >= (BASE << 4)) a -= (BASE << 4); \␊ |
49 | if (a >= (BASE << 3)) a -= (BASE << 3); \␊ |
50 | if (a >= (BASE << 2)) a -= (BASE << 2); \␊ |
51 | if (a >= (BASE << 1)) a -= (BASE << 1); \␊ |
52 | if (a >= BASE) a -= BASE; \␊ |
53 | } while (0)␊ |
54 | #else␊ |
55 | # define MOD(a) a %= BASE␊ |
56 | # define MOD4(a) a %= BASE␊ |
57 | #endif␊ |
58 | ␊ |
59 | /* ========================================================================= */␊ |
60 | uLong ZEXPORT adler32(adler, buf, len)␊ |
61 | uLong adler;␊ |
62 | const Bytef *buf;␊ |
63 | uInt len;␊ |
64 | {␊ |
65 | unsigned long sum2;␊ |
66 | unsigned n;␊ |
67 | ␊ |
68 | /* split Adler-32 into component sums */␊ |
69 | sum2 = (adler >> 16) & 0xffff;␊ |
70 | adler &= 0xffff;␊ |
71 | ␊ |
72 | /* in case user likes doing a byte at a time, keep it fast */␊ |
73 | if (len == 1) {␊ |
74 | adler += buf[0];␊ |
75 | if (adler >= BASE)␊ |
76 | adler -= BASE;␊ |
77 | sum2 += adler;␊ |
78 | if (sum2 >= BASE)␊ |
79 | sum2 -= BASE;␊ |
80 | return adler | (sum2 << 16);␊ |
81 | }␊ |
82 | ␊ |
83 | /* initial Adler-32 value (deferred check for len == 1 speed) */␊ |
84 | if (buf == Z_NULL)␊ |
85 | return 1L;␊ |
86 | ␊ |
87 | /* in case short lengths are provided, keep it somewhat fast */␊ |
88 | if (len < 16) {␊ |
89 | while (len--) {␊ |
90 | adler += *buf++;␊ |
91 | sum2 += adler;␊ |
92 | }␊ |
93 | if (adler >= BASE)␊ |
94 | adler -= BASE;␊ |
95 | MOD4(sum2); /* only added so many BASE's */␊ |
96 | return adler | (sum2 << 16);␊ |
97 | }␊ |
98 | ␊ |
99 | /* do length NMAX blocks -- requires just one modulo operation */␊ |
100 | while (len >= NMAX) {␊ |
101 | len -= NMAX;␊ |
102 | n = NMAX / 16; /* NMAX is divisible by 16 */␊ |
103 | do {␊ |
104 | DO16(buf); /* 16 sums unrolled */␊ |
105 | buf += 16;␊ |
106 | } while (--n);␊ |
107 | MOD(adler);␊ |
108 | MOD(sum2);␊ |
109 | }␊ |
110 | ␊ |
111 | /* do remaining bytes (less than NMAX, still just one modulo) */␊ |
112 | if (len) { /* avoid modulos if none remaining */␊ |
113 | while (len >= 16) {␊ |
114 | len -= 16;␊ |
115 | DO16(buf);␊ |
116 | buf += 16;␊ |
117 | }␊ |
118 | while (len--) {␊ |
119 | adler += *buf++;␊ |
120 | sum2 += adler;␊ |
121 | }␊ |
122 | MOD(adler);␊ |
123 | MOD(sum2);␊ |
124 | }␊ |
125 | ␊ |
126 | /* return recombined sums */␊ |
127 | return adler | (sum2 << 16);␊ |
128 | }␊ |
129 | ␊ |
130 | /* ========================================================================= */␊ |
131 | local uLong adler32_combine_(adler1, adler2, len2)␊ |
132 | uLong adler1;␊ |
133 | uLong adler2;␊ |
134 | z_off64_t len2;␊ |
135 | {␊ |
136 | unsigned long sum1;␊ |
137 | unsigned long sum2;␊ |
138 | unsigned rem;␊ |
139 | ␊ |
140 | /* the derivation of this formula is left as an exercise for the reader */␊ |
141 | rem = (unsigned)(len2 % BASE);␊ |
142 | sum1 = adler1 & 0xffff;␊ |
143 | sum2 = rem * sum1;␊ |
144 | MOD(sum2);␊ |
145 | sum1 += (adler2 & 0xffff) + BASE - 1;␊ |
146 | sum2 += ((adler1 >> 16) & 0xffff) + ((adler2 >> 16) & 0xffff) + BASE - rem;␊ |
147 | if (sum1 >= BASE) sum1 -= BASE;␊ |
148 | if (sum1 >= BASE) sum1 -= BASE;␊ |
149 | if (sum2 >= (BASE << 1)) sum2 -= (BASE << 1);␊ |
150 | if (sum2 >= BASE) sum2 -= BASE;␊ |
151 | return sum1 | (sum2 << 16);␊ |
152 | }␊ |
153 | ␊ |
154 | /* ========================================================================= */␊ |
155 | uLong ZEXPORT adler32_combine(adler1, adler2, len2)␊ |
156 | uLong adler1;␊ |
157 | uLong adler2;␊ |
158 | z_off_t len2;␊ |
159 | {␊ |
160 | return adler32_combine_(adler1, adler2, len2);␊ |
161 | }␊ |
162 | ␊ |
163 | uLong ZEXPORT adler32_combine64(adler1, adler2, len2)␊ |
164 | uLong adler1;␊ |
165 | uLong adler2;␊ |
166 | z_off64_t len2;␊ |
167 | {␊ |
168 | return adler32_combine_(adler1, adler2, len2);␊ |
169 | }␊ |
170 |