| Geant4 Cross Reference |
1 /* adler32.c -- compute the Adler-32 checksum 1 /* adler32.c -- compute the Adler-32 checksum of a data stream
2 * Copyright (C) 1995-2011, 2016 Mark Adler 2 * Copyright (C) 1995-2011, 2016 Mark Adler
3 * For conditions of distribution and use, see 3 * For conditions of distribution and use, see copyright notice in zlib.h
4 */ 4 */
5 5
6 /* @(#) $Id$ */ <<
7 6
8 #include "zutil.h" 7 #include "zutil.h"
9 8
10 local uLong adler32_combine_ OF((uLong adler1, 9 local uLong adler32_combine_ OF((uLong adler1, uLong adler2, z_off64_t len2));
11 10
12 #define BASE 65521U /* largest prime small 11 #define BASE 65521U /* largest prime smaller than 65536 */
13 #define NMAX 5552 12 #define NMAX 5552
14 /* NMAX is the largest n such that 255n(n+1)/2 13 /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
15 14
16 #define DO1(buf,i) {adler += (buf)[i]; sum2 + 15 #define DO1(buf,i) {adler += (buf)[i]; sum2 += adler;}
17 #define DO2(buf,i) DO1(buf,i); DO1(buf,i+1); 16 #define DO2(buf,i) DO1(buf,i); DO1(buf,i+1);
18 #define DO4(buf,i) DO2(buf,i); DO2(buf,i+2); 17 #define DO4(buf,i) DO2(buf,i); DO2(buf,i+2);
19 #define DO8(buf,i) DO4(buf,i); DO4(buf,i+4); 18 #define DO8(buf,i) DO4(buf,i); DO4(buf,i+4);
20 #define DO16(buf) DO8(buf,0); DO8(buf,8); 19 #define DO16(buf) DO8(buf,0); DO8(buf,8);
21 20
22 /* use NO_DIVIDE if your processor does not do 21 /* use NO_DIVIDE if your processor does not do division in hardware --
23 try it both ways to see which is faster */ 22 try it both ways to see which is faster */
24 #ifdef NO_DIVIDE 23 #ifdef NO_DIVIDE
25 /* note that this assumes BASE is 65521, where 24 /* note that this assumes BASE is 65521, where 65536 % 65521 == 15
26 (thank you to John Reiser for pointing this 25 (thank you to John Reiser for pointing this out) */
27 # define CHOP(a) \ 26 # define CHOP(a) \
28 do { \ 27 do { \
29 unsigned long tmp = a >> 16; \ 28 unsigned long tmp = a >> 16; \
30 a &= 0xffffUL; \ 29 a &= 0xffffUL; \
31 a += (tmp << 4) - tmp; \ 30 a += (tmp << 4) - tmp; \
32 } while (0) 31 } while (0)
33 # define MOD28(a) \ 32 # define MOD28(a) \
34 do { \ 33 do { \
35 CHOP(a); \ 34 CHOP(a); \
36 if (a >= BASE) a -= BASE; \ 35 if (a >= BASE) a -= BASE; \
37 } while (0) 36 } while (0)
38 # define MOD(a) \ 37 # define MOD(a) \
39 do { \ 38 do { \
40 CHOP(a); \ 39 CHOP(a); \
41 MOD28(a); \ 40 MOD28(a); \
42 } while (0) 41 } while (0)
43 # define MOD63(a) \ 42 # define MOD63(a) \
44 do { /* this assumes a is not negative */ 43 do { /* this assumes a is not negative */ \
45 z_off64_t tmp = a >> 32; \ 44 z_off64_t tmp = a >> 32; \
46 a &= 0xffffffffL; \ 45 a &= 0xffffffffL; \
47 a += (tmp << 8) - (tmp << 5) + tmp; \ 46 a += (tmp << 8) - (tmp << 5) + tmp; \
48 tmp = a >> 16; \ 47 tmp = a >> 16; \
49 a &= 0xffffL; \ 48 a &= 0xffffL; \
50 a += (tmp << 4) - tmp; \ 49 a += (tmp << 4) - tmp; \
51 tmp = a >> 16; \ 50 tmp = a >> 16; \
52 a &= 0xffffL; \ 51 a &= 0xffffL; \
53 a += (tmp << 4) - tmp; \ 52 a += (tmp << 4) - tmp; \
54 if (a >= BASE) a -= BASE; \ 53 if (a >= BASE) a -= BASE; \
55 } while (0) 54 } while (0)
56 #else 55 #else
57 # define MOD(a) a %= BASE 56 # define MOD(a) a %= BASE
58 # define MOD28(a) a %= BASE 57 # define MOD28(a) a %= BASE
59 # define MOD63(a) a %= BASE 58 # define MOD63(a) a %= BASE
60 #endif 59 #endif
61 60
62 /* =========================================== 61 /* ========================================================================= */
63 uLong ZEXPORT adler32_z(adler, buf, len) 62 uLong ZEXPORT adler32_z(adler, buf, len)
64 uLong adler; 63 uLong adler;
65 const Bytef *buf; 64 const Bytef *buf;
66 z_size_t len; 65 z_size_t len;
67 { 66 {
68 unsigned long sum2; 67 unsigned long sum2;
69 unsigned n; 68 unsigned n;
70 69
71 /* split Adler-32 into component sums */ 70 /* split Adler-32 into component sums */
72 sum2 = (adler >> 16) & 0xffff; 71 sum2 = (adler >> 16) & 0xffff;
73 adler &= 0xffff; 72 adler &= 0xffff;
74 73
75 /* in case user likes doing a byte at a ti 74 /* in case user likes doing a byte at a time, keep it fast */
76 if (len == 1) { 75 if (len == 1) {
77 adler += buf[0]; 76 adler += buf[0];
78 if (adler >= BASE) 77 if (adler >= BASE)
79 adler -= BASE; 78 adler -= BASE;
80 sum2 += adler; 79 sum2 += adler;
81 if (sum2 >= BASE) 80 if (sum2 >= BASE)
82 sum2 -= BASE; 81 sum2 -= BASE;
83 return adler | (sum2 << 16); 82 return adler | (sum2 << 16);
84 } 83 }
85 84
86 /* initial Adler-32 value (deferred check 85 /* initial Adler-32 value (deferred check for len == 1 speed) */
87 if (buf == Z_NULL) 86 if (buf == Z_NULL)
88 return 1L; 87 return 1L;
89 88
90 /* in case short lengths are provided, kee 89 /* in case short lengths are provided, keep it somewhat fast */
91 if (len < 16) { 90 if (len < 16) {
92 while (len--) { 91 while (len--) {
93 adler += *buf++; 92 adler += *buf++;
94 sum2 += adler; 93 sum2 += adler;
95 } 94 }
96 if (adler >= BASE) 95 if (adler >= BASE)
97 adler -= BASE; 96 adler -= BASE;
98 MOD28(sum2); /* only added 97 MOD28(sum2); /* only added so many BASE's */
99 return adler | (sum2 << 16); 98 return adler | (sum2 << 16);
100 } 99 }
101 100
102 /* do length NMAX blocks -- requires just 101 /* do length NMAX blocks -- requires just one modulo operation */
103 while (len >= NMAX) { 102 while (len >= NMAX) {
104 len -= NMAX; 103 len -= NMAX;
105 n = NMAX / 16; /* NMAX is div 104 n = NMAX / 16; /* NMAX is divisible by 16 */
106 do { 105 do {
107 DO16(buf); /* 16 sums unr 106 DO16(buf); /* 16 sums unrolled */
108 buf += 16; 107 buf += 16;
109 } while (--n); 108 } while (--n);
110 MOD(adler); 109 MOD(adler);
111 MOD(sum2); 110 MOD(sum2);
112 } 111 }
113 112
114 /* do remaining bytes (less than NMAX, sti 113 /* do remaining bytes (less than NMAX, still just one modulo) */
115 if (len) { /* avoid modul 114 if (len) { /* avoid modulos if none remaining */
116 while (len >= 16) { 115 while (len >= 16) {
117 len -= 16; 116 len -= 16;
118 DO16(buf); 117 DO16(buf);
119 buf += 16; 118 buf += 16;
120 } 119 }
121 while (len--) { 120 while (len--) {
122 adler += *buf++; 121 adler += *buf++;
123 sum2 += adler; 122 sum2 += adler;
124 } 123 }
125 MOD(adler); 124 MOD(adler);
126 MOD(sum2); 125 MOD(sum2);
127 } 126 }
128 127
129 /* return recombined sums */ 128 /* return recombined sums */
130 return adler | (sum2 << 16); 129 return adler | (sum2 << 16);
131 } 130 }
132 131
133 /* =========================================== 132 /* ========================================================================= */
134 uLong ZEXPORT adler32(adler, buf, len) 133 uLong ZEXPORT adler32(adler, buf, len)
135 uLong adler; 134 uLong adler;
136 const Bytef *buf; 135 const Bytef *buf;
137 uInt len; 136 uInt len;
138 { 137 {
139 return adler32_z(adler, buf, len); 138 return adler32_z(adler, buf, len);
140 } 139 }
141 140
142 /* =========================================== 141 /* ========================================================================= */
143 local uLong adler32_combine_(adler1, adler2, l 142 local uLong adler32_combine_(adler1, adler2, len2)
144 uLong adler1; 143 uLong adler1;
145 uLong adler2; 144 uLong adler2;
146 z_off64_t len2; 145 z_off64_t len2;
147 { 146 {
148 unsigned long sum1; 147 unsigned long sum1;
149 unsigned long sum2; 148 unsigned long sum2;
150 unsigned rem; 149 unsigned rem;
151 150
152 /* for negative len, return invalid adler3 151 /* for negative len, return invalid adler32 as a clue for debugging */
153 if (len2 < 0) 152 if (len2 < 0)
154 return 0xffffffffUL; 153 return 0xffffffffUL;
155 154
156 /* the derivation of this formula is left 155 /* the derivation of this formula is left as an exercise for the reader */
157 MOD63(len2); /* assumes len 156 MOD63(len2); /* assumes len2 >= 0 */
158 rem = (unsigned)len2; 157 rem = (unsigned)len2;
159 sum1 = adler1 & 0xffff; 158 sum1 = adler1 & 0xffff;
160 sum2 = rem * sum1; 159 sum2 = rem * sum1;
161 MOD(sum2); 160 MOD(sum2);
162 sum1 += (adler2 & 0xffff) + BASE - 1; 161 sum1 += (adler2 & 0xffff) + BASE - 1;
163 sum2 += ((adler1 >> 16) & 0xffff) + ((adle 162 sum2 += ((adler1 >> 16) & 0xffff) + ((adler2 >> 16) & 0xffff) + BASE - rem;
164 if (sum1 >= BASE) sum1 -= BASE; 163 if (sum1 >= BASE) sum1 -= BASE;
165 if (sum1 >= BASE) sum1 -= BASE; 164 if (sum1 >= BASE) sum1 -= BASE;
166 if (sum2 >= ((unsigned long)BASE << 1)) su 165 if (sum2 >= ((unsigned long)BASE << 1)) sum2 -= ((unsigned long)BASE << 1);
167 if (sum2 >= BASE) sum2 -= BASE; 166 if (sum2 >= BASE) sum2 -= BASE;
168 return sum1 | (sum2 << 16); 167 return sum1 | (sum2 << 16);
169 } 168 }
170 169
171 /* =========================================== 170 /* ========================================================================= */
172 uLong ZEXPORT adler32_combine(adler1, adler2, 171 uLong ZEXPORT adler32_combine(adler1, adler2, len2)
173 uLong adler1; 172 uLong adler1;
174 uLong adler2; 173 uLong adler2;
175 z_off_t len2; 174 z_off_t len2;
176 { 175 {
177 return adler32_combine_(adler1, adler2, le 176 return adler32_combine_(adler1, adler2, len2);
178 } 177 }
179 178
180 uLong ZEXPORT adler32_combine64(adler1, adler2 179 uLong ZEXPORT adler32_combine64(adler1, adler2, len2)
181 uLong adler1; 180 uLong adler1;
182 uLong adler2; 181 uLong adler2;
183 z_off64_t len2; 182 z_off64_t len2;
184 { 183 {
185 return adler32_combine_(adler1, adler2, le 184 return adler32_combine_(adler1, adler2, len2);
186 } 185 }
187 186