1/* adler32.c -- compute the Adler-32 checksum of a data stream
| 1/* adler32.c -- compute the Adler-32 checksum of a data stream
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2 * Copyright (C) 1995-2002 Mark Adler 3 * For conditions of distribution and use, see copyright notice in zlib.h
| 2 * Copyright (C) 1995-2003 Mark Adler 3 * For conditions of distribution and use, see copyright notice in zlib.h
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4 */ 5 6/* @(#) $Id$ */ 7
| 4 */ 5 6/* @(#) $Id$ */ 7
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| 8#define ZLIB_INTERNAL
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8#include "zlib.h" 9
| 9#include "zlib.h" 10
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10#define BASE 65521L /* largest prime smaller than 65536 */
| 11#define BASE 65521UL /* largest prime smaller than 65536 */
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11#define NMAX 5552 12/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */ 13 14#define DO1(buf,i) {s1 += buf[i]; s2 += s1;} 15#define DO2(buf,i) DO1(buf,i); DO1(buf,i+1); 16#define DO4(buf,i) DO2(buf,i); DO2(buf,i+2); 17#define DO8(buf,i) DO4(buf,i); DO4(buf,i+4); 18#define DO16(buf) DO8(buf,0); DO8(buf,8); 19
| 12#define NMAX 5552 13/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */ 14 15#define DO1(buf,i) {s1 += buf[i]; s2 += s1;} 16#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 DO8(buf,i) DO4(buf,i); DO4(buf,i+4); 19#define DO16(buf) DO8(buf,0); DO8(buf,8); 20
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| 21#ifdef NO_DIVIDE 22# define MOD(a) \ 23 do { \ 24 if (a >= (BASE << 16)) a -= (BASE << 16); \ 25 if (a >= (BASE << 15)) a -= (BASE << 15); \ 26 if (a >= (BASE << 14)) a -= (BASE << 14); \ 27 if (a >= (BASE << 13)) a -= (BASE << 13); \ 28 if (a >= (BASE << 12)) a -= (BASE << 12); \ 29 if (a >= (BASE << 11)) a -= (BASE << 11); \ 30 if (a >= (BASE << 10)) a -= (BASE << 10); \ 31 if (a >= (BASE << 9)) a -= (BASE << 9); \ 32 if (a >= (BASE << 8)) a -= (BASE << 8); \ 33 if (a >= (BASE << 7)) a -= (BASE << 7); \ 34 if (a >= (BASE << 6)) a -= (BASE << 6); \ 35 if (a >= (BASE << 5)) a -= (BASE << 5); \ 36 if (a >= (BASE << 4)) a -= (BASE << 4); \ 37 if (a >= (BASE << 3)) a -= (BASE << 3); \ 38 if (a >= (BASE << 2)) a -= (BASE << 2); \ 39 if (a >= (BASE << 1)) a -= (BASE << 1); \ 40 if (a >= BASE) a -= BASE; \ 41 } while (0) 42#else 43# define MOD(a) a %= BASE 44#endif 45
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20/* ========================================================================= */ 21uLong ZEXPORT adler32(adler, buf, len) 22 uLong adler; 23 const Bytef *buf; 24 uInt len; 25{ 26 unsigned long s1 = adler & 0xffff; 27 unsigned long s2 = (adler >> 16) & 0xffff; 28 int k; 29 30 if (buf == Z_NULL) return 1L; 31 32 while (len > 0) {
| 46/* ========================================================================= */ 47uLong ZEXPORT adler32(adler, buf, len) 48 uLong adler; 49 const Bytef *buf; 50 uInt len; 51{ 52 unsigned long s1 = adler & 0xffff; 53 unsigned long s2 = (adler >> 16) & 0xffff; 54 int k; 55 56 if (buf == Z_NULL) return 1L; 57 58 while (len > 0) {
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33 k = len < NMAX ? len : NMAX;
| 59 k = len < NMAX ? (int)len : NMAX;
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34 len -= k; 35 while (k >= 16) { 36 DO16(buf);
| 60 len -= k; 61 while (k >= 16) { 62 DO16(buf);
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37 buf += 16;
| 63 buf += 16;
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38 k -= 16; 39 } 40 if (k != 0) do { 41 s1 += *buf++;
| 64 k -= 16; 65 } 66 if (k != 0) do { 67 s1 += *buf++;
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42 s2 += s1;
| 68 s2 += s1;
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43 } while (--k);
| 69 } while (--k);
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44 s1 %= BASE; 45 s2 %= BASE;
| 70 MOD(s1); 71 MOD(s2);
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46 } 47 return (s2 << 16) | s1; 48}
| 72 } 73 return (s2 << 16) | s1; 74}
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