1ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov/* adler32.c -- compute the Adler-32 checksum of a data stream 2ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov * Copyright (C) 1995-2011 Mark Adler 3ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov * For conditions of distribution and use, see copyright notice in zlib.h 4ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov */ 5ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 6ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov/* @(#) $Id$ */ 7ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 8ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov#include "zutil.h" 9ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 10ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov#define local static 11ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 12ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganovlocal uLong adler32_combine_ OF((uLong adler1, uLong adler2, z_off64_t len2)); 13ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 14ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov#define BASE 65521 /* largest prime smaller than 65536 */ 15ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov#define NMAX 5552 16ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */ 17ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 18ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov#define DO1(buf,i) {adler += (buf)[i]; sum2 += adler;} 19ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov#define DO2(buf,i) DO1(buf,i); DO1(buf,i+1); 20ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov#define DO4(buf,i) DO2(buf,i); DO2(buf,i+2); 21ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov#define DO8(buf,i) DO4(buf,i); DO4(buf,i+4); 22ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov#define DO16(buf) DO8(buf,0); DO8(buf,8); 23ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 24ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov/* use NO_DIVIDE if your processor does not do division in hardware -- 25ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov try it both ways to see which is faster */ 26ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov#ifdef NO_DIVIDE 27ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov/* note that this assumes BASE is 65521, where 65536 % 65521 == 15 28ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov (thank you to John Reiser for pointing this out) */ 29ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov# define CHOP(a) \ 30ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov do { \ 31ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned long tmp = a >> 16; \ 32ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov a &= 0xffffUL; \ 33ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov a += (tmp << 4) - tmp; \ 34ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } while (0) 35ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov# define MOD28(a) \ 36ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov do { \ 37ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov CHOP(a); \ 38ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (a >= BASE) a -= BASE; \ 39ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } while (0) 40ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov# define MOD(a) \ 41ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov do { \ 42ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov CHOP(a); \ 43ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov MOD28(a); \ 44ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } while (0) 45ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov# define MOD63(a) \ 46ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov do { /* this assumes a is not negative */ \ 47ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov z_off64_t tmp = a >> 32; \ 48ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov a &= 0xffffffffL; \ 49ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov a += (tmp << 8) - (tmp << 5) + tmp; \ 50ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov tmp = a >> 16; \ 51ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov a &= 0xffffL; \ 52ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov a += (tmp << 4) - tmp; \ 53ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov tmp = a >> 16; \ 54ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov a &= 0xffffL; \ 55ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov a += (tmp << 4) - tmp; \ 56ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (a >= BASE) a -= BASE; \ 57ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } while (0) 58ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov#else 59ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov# define MOD(a) a %= BASE 60ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov# define MOD28(a) a %= BASE 61ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov# define MOD63(a) a %= BASE 62ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov#endif 63ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 64ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov/* ========================================================================= */ 65ee451cb395940862dad63c85adfe8f2fd55e864cSvet GanovuLong ZEXPORT adler32( 66ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov uLong adler, 67ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov const Bytef *buf, 68ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov uInt len) 69ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov{ 70ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned long sum2; 71ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned n; 72ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 73ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* split Adler-32 into component sums */ 74ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov sum2 = (adler >> 16) & 0xffff; 75ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov adler &= 0xffff; 76ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 77ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* in case user likes doing a byte at a time, keep it fast */ 78ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (len == 1) { 79ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov adler += buf[0]; 80ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (adler >= BASE) 81ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov adler -= BASE; 82ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov sum2 += adler; 83ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (sum2 >= BASE) 84ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov sum2 -= BASE; 85ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov return adler | (sum2 << 16); 86ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 87ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 88ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* initial Adler-32 value (deferred check for len == 1 speed) */ 89ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (buf == Z_NULL) 90ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov return 1L; 91ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 92ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* in case short lengths are provided, keep it somewhat fast */ 93ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (len < 16) { 94ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov while (len--) { 95ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov adler += *buf++; 96ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov sum2 += adler; 97ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 98ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (adler >= BASE) 99ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov adler -= BASE; 100ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov MOD28(sum2); /* only added so many BASE's */ 101ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov return adler | (sum2 << 16); 102ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 103ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 104ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* do length NMAX blocks -- requires just one modulo operation */ 105ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov while (len >= NMAX) { 106ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov len -= NMAX; 107ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov n = NMAX / 16; /* NMAX is divisible by 16 */ 108ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov do { 109ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov DO16(buf); /* 16 sums unrolled */ 110ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov buf += 16; 111ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } while (--n); 112ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov MOD(adler); 113ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov MOD(sum2); 114ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 115ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 116ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* do remaining bytes (less than NMAX, still just one modulo) */ 117ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (len) { /* avoid modulos if none remaining */ 118ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov while (len >= 16) { 119ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov len -= 16; 120ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov DO16(buf); 121ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov buf += 16; 122ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 123ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov while (len--) { 124ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov adler += *buf++; 125ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov sum2 += adler; 126ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 127ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov MOD(adler); 128ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov MOD(sum2); 129ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 130ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 131ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* return recombined sums */ 132ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov return adler | (sum2 << 16); 133ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov} 134ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 135ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov/* ========================================================================= */ 136ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganovlocal uLong adler32_combine_( 137ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov uLong adler1, 138ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov uLong adler2, 139ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov z_off64_t len2) 140ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov{ 141ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned long sum1; 142ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned long sum2; 143ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned rem; 144ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 145ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* for negative len, return invalid adler32 as a clue for debugging */ 146ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (len2 < 0) 147ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov return 0xffffffffUL; 148ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 149ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* the derivation of this formula is left as an exercise for the reader */ 150ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov MOD63(len2); /* assumes len2 >= 0 */ 151ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov rem = (unsigned)len2; 152ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov sum1 = adler1 & 0xffff; 153ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov sum2 = rem * sum1; 154ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov MOD(sum2); 155ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov sum1 += (adler2 & 0xffff) + BASE - 1; 156ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov sum2 += ((adler1 >> 16) & 0xffff) + ((adler2 >> 16) & 0xffff) + BASE - rem; 157ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (sum1 >= BASE) sum1 -= BASE; 158ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (sum1 >= BASE) sum1 -= BASE; 159ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (sum2 >= (BASE << 1)) sum2 -= (BASE << 1); 160ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (sum2 >= BASE) sum2 -= BASE; 161ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov return sum1 | (sum2 << 16); 162ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov} 163ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 164ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov/* ========================================================================= */ 165ee451cb395940862dad63c85adfe8f2fd55e864cSvet GanovuLong ZEXPORT adler32_combine( 166ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov uLong adler1, 167ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov uLong adler2, 168ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov z_off_t len2) 169ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov{ 170ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov return adler32_combine_(adler1, adler2, len2); 171ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov} 172ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 173ee451cb395940862dad63c85adfe8f2fd55e864cSvet GanovuLong ZEXPORT adler32_combine64( 174ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov uLong adler1, 175ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov uLong adler2, 176ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov z_off64_t len2) 177ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov{ 178ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov return adler32_combine_(adler1, adler2, len2); 179ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov} 180