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comparison zlib/adler32.c @ 111:04ced10e8804

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gcc 7
author kono
date Fri, 27 Oct 2017 22:46:09 +0900
parents ae3a4bfb450b
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68:561a7518be6b 111:04ced10e8804
1 /* adler32.c -- compute the Adler-32 checksum of a data stream 1 /* adler32.c -- compute the Adler-32 checksum of a data stream
2 * Copyright (C) 1995-2004 Mark Adler 2 * Copyright (C) 1995-2011, 2016 Mark Adler
3 * For conditions of distribution and use, see copyright notice in zlib.h 3 * For conditions of distribution and use, see copyright notice in zlib.h
4 */ 4 */
5 5
6 /* @(#) $Id: adler32.c,v 1.1.1.2 2002/03/11 21:53:23 tromey Exp $ */ 6 /* @(#) $Id: adler32.c,v 1.1.1.2 2002/03/11 21:53:23 tromey Exp $ */
7 7
8 #define ZLIB_INTERNAL 8 #include "zutil.h"
9 #include "zlib.h"
10 9
11 #define BASE 65521UL /* largest prime smaller than 65536 */ 10 local uLong adler32_combine_ OF((uLong adler1, uLong adler2, z_off64_t len2));
11
12 #define BASE 65521U /* largest prime smaller than 65536 */
12 #define NMAX 5552 13 #define NMAX 5552
13 /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */ 14 /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
14 15
15 #define DO1(buf,i) {adler += (buf)[i]; sum2 += adler;} 16 #define DO1(buf,i) {adler += (buf)[i]; sum2 += adler;}
16 #define DO2(buf,i) DO1(buf,i); DO1(buf,i+1); 17 #define DO2(buf,i) DO1(buf,i); DO1(buf,i+1);
17 #define DO4(buf,i) DO2(buf,i); DO2(buf,i+2); 18 #define DO4(buf,i) DO2(buf,i); DO2(buf,i+2);
18 #define DO8(buf,i) DO4(buf,i); DO4(buf,i+4); 19 #define DO8(buf,i) DO4(buf,i); DO4(buf,i+4);
19 #define DO16(buf) DO8(buf,0); DO8(buf,8); 20 #define DO16(buf) DO8(buf,0); DO8(buf,8);
20 21
21 /* use NO_DIVIDE if your processor does not do division in hardware */ 22 /* use NO_DIVIDE if your processor does not do division in hardware --
23 try it both ways to see which is faster */
22 #ifdef NO_DIVIDE 24 #ifdef NO_DIVIDE
25 /* note that this assumes BASE is 65521, where 65536 % 65521 == 15
26 (thank you to John Reiser for pointing this out) */
27 # define CHOP(a) \
28 do { \
29 unsigned long tmp = a >> 16; \
30 a &= 0xffffUL; \
31 a += (tmp << 4) - tmp; \
32 } while (0)
33 # define MOD28(a) \
34 do { \
35 CHOP(a); \
36 if (a >= BASE) a -= BASE; \
37 } while (0)
23 # define MOD(a) \ 38 # define MOD(a) \
24 do { \ 39 do { \
25 if (a >= (BASE << 16)) a -= (BASE << 16); \ 40 CHOP(a); \
26 if (a >= (BASE << 15)) a -= (BASE << 15); \ 41 MOD28(a); \
27 if (a >= (BASE << 14)) a -= (BASE << 14); \
28 if (a >= (BASE << 13)) a -= (BASE << 13); \
29 if (a >= (BASE << 12)) a -= (BASE << 12); \
30 if (a >= (BASE << 11)) a -= (BASE << 11); \
31 if (a >= (BASE << 10)) a -= (BASE << 10); \
32 if (a >= (BASE << 9)) a -= (BASE << 9); \
33 if (a >= (BASE << 8)) a -= (BASE << 8); \
34 if (a >= (BASE << 7)) a -= (BASE << 7); \
35 if (a >= (BASE << 6)) a -= (BASE << 6); \
36 if (a >= (BASE << 5)) a -= (BASE << 5); \
37 if (a >= (BASE << 4)) a -= (BASE << 4); \
38 if (a >= (BASE << 3)) a -= (BASE << 3); \
39 if (a >= (BASE << 2)) a -= (BASE << 2); \
40 if (a >= (BASE << 1)) a -= (BASE << 1); \
41 if (a >= BASE) a -= BASE; \
42 } while (0) 42 } while (0)
43 # define MOD4(a) \ 43 # define MOD63(a) \
44 do { \ 44 do { /* this assumes a is not negative */ \
45 if (a >= (BASE << 4)) a -= (BASE << 4); \ 45 z_off64_t tmp = a >> 32; \
46 if (a >= (BASE << 3)) a -= (BASE << 3); \ 46 a &= 0xffffffffL; \
47 if (a >= (BASE << 2)) a -= (BASE << 2); \ 47 a += (tmp << 8) - (tmp << 5) + tmp; \
48 if (a >= (BASE << 1)) a -= (BASE << 1); \ 48 tmp = a >> 16; \
49 a &= 0xffffL; \
50 a += (tmp << 4) - tmp; \
51 tmp = a >> 16; \
52 a &= 0xffffL; \
53 a += (tmp << 4) - tmp; \
49 if (a >= BASE) a -= BASE; \ 54 if (a >= BASE) a -= BASE; \
50 } while (0) 55 } while (0)
51 #else 56 #else
52 # define MOD(a) a %= BASE 57 # define MOD(a) a %= BASE
53 # define MOD4(a) a %= BASE 58 # define MOD28(a) a %= BASE
59 # define MOD63(a) a %= BASE
54 #endif 60 #endif
55 61
56 /* ========================================================================= */ 62 /* ========================================================================= */
57 uLong ZEXPORT adler32(adler, buf, len) 63 uLong ZEXPORT adler32_z(adler, buf, len)
58 uLong adler; 64 uLong adler;
59 const Bytef *buf; 65 const Bytef *buf;
60 uInt len; 66 z_size_t len;
61 { 67 {
62 unsigned long sum2; 68 unsigned long sum2;
63 unsigned n; 69 unsigned n;
64 70
65 /* split Adler-32 into component sums */ 71 /* split Adler-32 into component sums */
87 adler += *buf++; 93 adler += *buf++;
88 sum2 += adler; 94 sum2 += adler;
89 } 95 }
90 if (adler >= BASE) 96 if (adler >= BASE)
91 adler -= BASE; 97 adler -= BASE;
92 MOD4(sum2); /* only added so many BASE's */ 98 MOD28(sum2); /* only added so many BASE's */
93 return adler | (sum2 << 16); 99 return adler | (sum2 << 16);
94 } 100 }
95 101
96 /* do length NMAX blocks -- requires just one modulo operation */ 102 /* do length NMAX blocks -- requires just one modulo operation */
97 while (len >= NMAX) { 103 while (len >= NMAX) {
123 /* return recombined sums */ 129 /* return recombined sums */
124 return adler | (sum2 << 16); 130 return adler | (sum2 << 16);
125 } 131 }
126 132
127 /* ========================================================================= */ 133 /* ========================================================================= */
134 uLong ZEXPORT adler32(adler, buf, len)
135 uLong adler;
136 const Bytef *buf;
137 uInt len;
138 {
139 return adler32_z(adler, buf, len);
140 }
141
142 /* ========================================================================= */
143 local uLong adler32_combine_(adler1, adler2, len2)
144 uLong adler1;
145 uLong adler2;
146 z_off64_t len2;
147 {
148 unsigned long sum1;
149 unsigned long sum2;
150 unsigned rem;
151
152 /* for negative len, return invalid adler32 as a clue for debugging */
153 if (len2 < 0)
154 return 0xffffffffUL;
155
156 /* the derivation of this formula is left as an exercise for the reader */
157 MOD63(len2); /* assumes len2 >= 0 */
158 rem = (unsigned)len2;
159 sum1 = adler1 & 0xffff;
160 sum2 = rem * sum1;
161 MOD(sum2);
162 sum1 += (adler2 & 0xffff) + BASE - 1;
163 sum2 += ((adler1 >> 16) & 0xffff) + ((adler2 >> 16) & 0xffff) + BASE - rem;
164 if (sum1 >= BASE) sum1 -= BASE;
165 if (sum1 >= BASE) sum1 -= BASE;
166 if (sum2 >= ((unsigned long)BASE << 1)) sum2 -= ((unsigned long)BASE << 1);
167 if (sum2 >= BASE) sum2 -= BASE;
168 return sum1 | (sum2 << 16);
169 }
170
171 /* ========================================================================= */
128 uLong ZEXPORT adler32_combine(adler1, adler2, len2) 172 uLong ZEXPORT adler32_combine(adler1, adler2, len2)
129 uLong adler1; 173 uLong adler1;
130 uLong adler2; 174 uLong adler2;
131 z_off_t len2; 175 z_off_t len2;
132 { 176 {
133 unsigned long sum1; 177 return adler32_combine_(adler1, adler2, len2);
134 unsigned long sum2; 178 }
135 unsigned rem;
136 179
137 /* the derivation of this formula is left as an exercise for the reader */ 180 uLong ZEXPORT adler32_combine64(adler1, adler2, len2)
138 rem = (unsigned)(len2 % BASE); 181 uLong adler1;
139 sum1 = adler1 & 0xffff; 182 uLong adler2;
140 sum2 = rem * sum1; 183 z_off64_t len2;
141 MOD(sum2); 184 {
142 sum1 += (adler2 & 0xffff) + BASE - 1; 185 return adler32_combine_(adler1, adler2, len2);
143 sum2 += ((adler1 >> 16) & 0xffff) + ((adler2 >> 16) & 0xffff) + BASE - rem;
144 if (sum1 > BASE) sum1 -= BASE;
145 if (sum1 > BASE) sum1 -= BASE;
146 if (sum2 > (BASE << 1)) sum2 -= (BASE << 1);
147 if (sum2 > BASE) sum2 -= BASE;
148 return sum1 | (sum2 << 16);
149 } 186 }