1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/os/ossrv/compressionlibs/ziplib/src/zlib/adler32.cpp Fri Jun 15 03:10:57 2012 +0200
1.3 @@ -0,0 +1,164 @@
1.4 +/* Portions Copyright (c) 2007-2009 Nokia Corporation and/or its subsidiary(-ies).
1.5 + * All rights reserved.
1.6 + */
1.7 +
1.8 +/* adler32.cpp -- compute the Adler-32 checksum of a data stream
1.9 + * Copyright (C) 1995-2004 Mark Adler
1.10 + * For conditions of distribution and use, see copyright notice in zlib.h
1.11 + */
1.12 +
1.13 +/* @(#) $Id$ */
1.14 +
1.15 +#define ZLIB_INTERNAL
1.16 +#include "libzcore.h"
1.17 +
1.18 +#define BASE 65521UL /* largest prime smaller than 65536 */
1.19 +#define NMAX 5552
1.20 +/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
1.21 +
1.22 +#define DO1(buf,i) {adler += (buf)[i]; sum2 += adler;}
1.23 +#define DO2(buf,i) DO1(buf,i); DO1(buf,i+1);
1.24 +#define DO4(buf,i) DO2(buf,i); DO2(buf,i+2);
1.25 +#define DO8(buf,i) DO4(buf,i); DO4(buf,i+4);
1.26 +#define DO16(buf) DO8(buf,0); DO8(buf,8);
1.27 +
1.28 +/* use NO_DIVIDE if your processor does not do division in hardware */
1.29 +#ifdef NO_DIVIDE
1.30 +# define MOD(a) \
1.31 + do { \
1.32 + if (a >= (BASE << 16)) a -= (BASE << 16); \
1.33 + if (a >= (BASE << 15)) a -= (BASE << 15); \
1.34 + if (a >= (BASE << 14)) a -= (BASE << 14); \
1.35 + if (a >= (BASE << 13)) a -= (BASE << 13); \
1.36 + if (a >= (BASE << 12)) a -= (BASE << 12); \
1.37 + if (a >= (BASE << 11)) a -= (BASE << 11); \
1.38 + if (a >= (BASE << 10)) a -= (BASE << 10); \
1.39 + if (a >= (BASE << 9)) a -= (BASE << 9); \
1.40 + if (a >= (BASE << 8)) a -= (BASE << 8); \
1.41 + if (a >= (BASE << 7)) a -= (BASE << 7); \
1.42 + if (a >= (BASE << 6)) a -= (BASE << 6); \
1.43 + if (a >= (BASE << 5)) a -= (BASE << 5); \
1.44 + if (a >= (BASE << 4)) a -= (BASE << 4); \
1.45 + if (a >= (BASE << 3)) a -= (BASE << 3); \
1.46 + if (a >= (BASE << 2)) a -= (BASE << 2); \
1.47 + if (a >= (BASE << 1)) a -= (BASE << 1); \
1.48 + if (a >= BASE) a -= BASE; \
1.49 + } while (0)
1.50 +# define MOD4(a) \
1.51 + do { \
1.52 + if (a >= (BASE << 4)) a -= (BASE << 4); \
1.53 + if (a >= (BASE << 3)) a -= (BASE << 3); \
1.54 + if (a >= (BASE << 2)) a -= (BASE << 2); \
1.55 + if (a >= (BASE << 1)) a -= (BASE << 1); \
1.56 + if (a >= BASE) a -= BASE; \
1.57 + } while (0)
1.58 +#else
1.59 +# define MOD(a) a %= BASE
1.60 +# define MOD4(a) a %= BASE
1.61 +#endif
1.62 +
1.63 +/* ========================================================================= */
1.64 +
1.65 +
1.66 +#ifdef __SYMBIAN32__
1.67 +EXPORT_C uLong adler32_r(uLong adler,const Bytef * buf,uInt len)
1.68 +#else
1.69 +uLong ZEXPORT adler32(adler, buf, len)
1.70 + uLong adler;
1.71 + const Bytef *buf;
1.72 + uInt len;
1.73 +#endif /* __SYMBIAN32__ */
1.74 +{
1.75 + unsigned long sum2;
1.76 + unsigned n;
1.77 +
1.78 + /* split Adler-32 into component sums */
1.79 + sum2 = (adler >> 16) & 0xffff;
1.80 + adler &= 0xffff;
1.81 +
1.82 + /* in case user likes doing a byte at a time, keep it fast */
1.83 + if (len == 1) {
1.84 + adler += buf[0];
1.85 + if (adler >= BASE)
1.86 + adler -= BASE;
1.87 + sum2 += adler;
1.88 + if (sum2 >= BASE)
1.89 + sum2 -= BASE;
1.90 + return adler | (sum2 << 16);
1.91 + }
1.92 +
1.93 + /* initial Adler-32 value (deferred check for len == 1 speed) */
1.94 + if (buf == Z_NULL)
1.95 + return 1L;
1.96 +
1.97 + /* in case short lengths are provided, keep it somewhat fast */
1.98 + if (len < 16) {
1.99 + while (len--) {
1.100 + adler += *buf++;
1.101 + sum2 += adler;
1.102 + }
1.103 + if (adler >= BASE)
1.104 + adler -= BASE;
1.105 + MOD4(sum2); /* only added so many BASE's */
1.106 + return adler | (sum2 << 16);
1.107 + }
1.108 +
1.109 + /* do length NMAX blocks -- requires just one modulo operation */
1.110 + while (len >= NMAX) {
1.111 + len -= NMAX;
1.112 + n = NMAX / 16; /* NMAX is divisible by 16 */
1.113 + do {
1.114 + DO16(buf); /* 16 sums unrolled */
1.115 + buf += 16;
1.116 + } while (--n);
1.117 + MOD(adler);
1.118 + MOD(sum2);
1.119 + }
1.120 +
1.121 + /* do remaining bytes (less than NMAX, still just one modulo) */
1.122 + if (len) { /* avoid modulos if none remaining */
1.123 + while (len >= 16) {
1.124 + len -= 16;
1.125 + DO16(buf);
1.126 + buf += 16;
1.127 + }
1.128 + while (len--) {
1.129 + adler += *buf++;
1.130 + sum2 += adler;
1.131 + }
1.132 + MOD(adler);
1.133 + MOD(sum2);
1.134 + }
1.135 +
1.136 + /* return recombined sums */
1.137 + return adler | (sum2 << 16);
1.138 +}
1.139 +
1.140 +/* ========================================================================= */
1.141 +
1.142 +#ifdef __SYMBIAN32__
1.143 +EXPORT_C uLong adler32_combine_r(uLong adler1, uLong adler2, z_off_t len2)
1.144 +#else
1.145 +uLong ZEXPORT adler32_combine(adler1, adler2, len2)
1.146 + uLong adler1;
1.147 + uLong adler2;
1.148 + z_off_t len2;
1.149 +#endif /* __SYMBIAN32__ */
1.150 +{
1.151 + unsigned long sum1;
1.152 + unsigned long sum2;
1.153 + unsigned rem;
1.154 +
1.155 + /* the derivation of this formula is left as an exercise for the reader */
1.156 + rem = (unsigned)(len2 % BASE);
1.157 + sum1 = adler1 & 0xffff;
1.158 + sum2 = rem * sum1;
1.159 + MOD(sum2);
1.160 + sum1 += (adler2 & 0xffff) + BASE - 1;
1.161 + sum2 += ((adler1 >> 16) & 0xffff) + ((adler2 >> 16) & 0xffff) + BASE - rem;
1.162 + if (sum1 > BASE) sum1 -= BASE;
1.163 + if (sum1 > BASE) sum1 -= BASE;
1.164 + if (sum2 > (BASE << 1)) sum2 -= (BASE << 1);
1.165 + if (sum2 > BASE) sum2 -= BASE;
1.166 + return sum1 | (sum2 << 16);
1.167 +}