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author | cvs2git <rtems-devel@rtems.org> | 2011-03-18 10:11:42 +0000 |
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committer | cvs2git <rtems-devel@rtems.org> | 2011-03-18 10:11:42 +0000 |
commit | e371ea9949ecc8897f4cb34437cc6590a0fc51f0 (patch) | |
tree | e5d17499fe12fc87c9697d681b63b062e9cbb65a /cpukit/zlib/adler32.c | |
parent | 83dcd23af45446b24fe12e5bce29432debe6d0b5 (diff) |
This commit was manufactured by cvs2svn to create tag 'rtems-4-10-0'.4.10.0
Sprout from rtems-4-10-branch 2011-02-08 15:56:24 UTC Joel Sherrill <joel.sherrill@OARcorp.com> 'Ensure all version instances say 4.10.'
Cherrypick from rtems-4-10-branch 2011-03-18 10:11:41 UTC cvs2git <rtems-devel@rtems.org> 'This commit was manufactured by cvs2svn to create branch':
cpukit/zlib/ChangeLog
cpukit/zlib/ChangeLog.zlib
cpukit/zlib/FAQ
cpukit/zlib/Makefile.am
cpukit/zlib/README
cpukit/zlib/adler32.c
cpukit/zlib/compress.c
cpukit/zlib/crc32.c
cpukit/zlib/deflate.c
cpukit/zlib/deflate.h
cpukit/zlib/doc/algorithm.txt
cpukit/zlib/gzclose.c
cpukit/zlib/gzguts.h
cpukit/zlib/gzlib.c
cpukit/zlib/gzread.c
cpukit/zlib/gzwrite.c
cpukit/zlib/infback.c
cpukit/zlib/inffast.c
cpukit/zlib/inflate.c
cpukit/zlib/inflate.h
cpukit/zlib/inftrees.c
cpukit/zlib/inftrees.h
cpukit/zlib/trees.c
cpukit/zlib/uncompr.c
cpukit/zlib/zconf.h
cpukit/zlib/zlib.3
cpukit/zlib/zlib.h
cpukit/zlib/zutil.c
cpukit/zlib/zutil.h
testsuites/libtests/mathf/.cvsignore
testsuites/libtests/mathf/Makefile.am
testsuites/libtests/mathf/domathf.c
testsuites/libtests/mathf/init.c
testsuites/libtests/mathf/mathf.scn
Diffstat (limited to 'cpukit/zlib/adler32.c')
-rw-r--r-- | cpukit/zlib/adler32.c | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/cpukit/zlib/adler32.c b/cpukit/zlib/adler32.c new file mode 100644 index 0000000000..6889548657 --- /dev/null +++ b/cpukit/zlib/adler32.c @@ -0,0 +1,171 @@ +/* adler32.c -- compute the Adler-32 checksum of a data stream + * Copyright (C) 1995-2007 Mark Adler + * For conditions of distribution and use, see copyright notice in zlib.h + */ + +/* @(#) $Id$ */ + +#include "zutil.h" + +#define local static + +local uLong adler32_combine_(uLong adler1, uLong adler2, z_off64_t len2); + +#define BASE 65521UL /* largest prime smaller than 65536 */ +#define NMAX 5552 +/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */ + +#define DO1(buf,i) {adler += (buf)[i]; sum2 += adler;} +#define DO2(buf,i) DO1(buf,i); DO1(buf,i+1); +#define DO4(buf,i) DO2(buf,i); DO2(buf,i+2); +#define DO8(buf,i) DO4(buf,i); DO4(buf,i+4); +#define DO16(buf) DO8(buf,0); DO8(buf,8); + +/* use NO_DIVIDE if your processor does not do division in hardware */ +#ifdef NO_DIVIDE +# define MOD(a) \ + do { \ + if (a >= (BASE << 16)) a -= (BASE << 16); \ + if (a >= (BASE << 15)) a -= (BASE << 15); \ + if (a >= (BASE << 14)) a -= (BASE << 14); \ + if (a >= (BASE << 13)) a -= (BASE << 13); \ + if (a >= (BASE << 12)) a -= (BASE << 12); \ + if (a >= (BASE << 11)) a -= (BASE << 11); \ + if (a >= (BASE << 10)) a -= (BASE << 10); \ + if (a >= (BASE << 9)) a -= (BASE << 9); \ + if (a >= (BASE << 8)) a -= (BASE << 8); \ + if (a >= (BASE << 7)) a -= (BASE << 7); \ + if (a >= (BASE << 6)) a -= (BASE << 6); \ + if (a >= (BASE << 5)) a -= (BASE << 5); \ + if (a >= (BASE << 4)) a -= (BASE << 4); \ + if (a >= (BASE << 3)) a -= (BASE << 3); \ + if (a >= (BASE << 2)) a -= (BASE << 2); \ + if (a >= (BASE << 1)) a -= (BASE << 1); \ + if (a >= BASE) a -= BASE; \ + } while (0) +# define MOD4(a) \ + do { \ + if (a >= (BASE << 4)) a -= (BASE << 4); \ + if (a >= (BASE << 3)) a -= (BASE << 3); \ + if (a >= (BASE << 2)) a -= (BASE << 2); \ + if (a >= (BASE << 1)) a -= (BASE << 1); \ + if (a >= BASE) a -= BASE; \ + } while (0) +#else +# define MOD(a) a %= BASE +# define MOD4(a) a %= BASE +#endif + +/* ========================================================================= */ +uLong ZEXPORT adler32(adler, buf, len) + uLong adler; + const Bytef *buf; + uInt len; +{ + unsigned long sum2; + unsigned n; + + /* split Adler-32 into component sums */ + sum2 = (adler >> 16) & 0xffff; + adler &= 0xffff; + + /* in case user likes doing a byte at a time, keep it fast */ + if (len == 1) { + adler += buf[0]; + if (adler >= BASE) + adler -= BASE; + sum2 += adler; + if (sum2 >= BASE) + sum2 -= BASE; + return adler | (sum2 << 16); + } + + /* initial Adler-32 value (deferred check for len == 1 speed) */ + if (buf == Z_NULL) + return 1L; + + /* in case short lengths are provided, keep it somewhat fast */ + if (len < 16) { + while (len--) { + adler += *buf++; + sum2 += adler; + } + if (adler >= BASE) + adler -= BASE; + MOD4(sum2); /* only added so many BASE's */ + return adler | (sum2 << 16); + } + + /* do length NMAX blocks -- requires just one modulo operation */ + while (len >= NMAX) { + len -= NMAX; + n = NMAX / 16; /* NMAX is divisible by 16 */ + do { + DO16(buf); /* 16 sums unrolled */ + buf += 16; + } while (--n); + MOD(adler); + MOD(sum2); + } + + /* do remaining bytes (less than NMAX, still just one modulo) */ + if (len) { /* avoid modulos if none remaining */ + while (len >= 16) { + len -= 16; + DO16(buf); + buf += 16; + } + while (len--) { + adler += *buf++; + sum2 += adler; + } + MOD(adler); + MOD(sum2); + } + + /* return recombined sums */ + return adler | (sum2 << 16); +} + +/* ========================================================================= */ +local uLong adler32_combine_(adler1, adler2, len2) + uLong adler1; + uLong adler2; + z_off64_t len2; +{ + unsigned long sum1; + unsigned long sum2; + unsigned rem; + + /* the derivation of this formula is left as an exercise for the reader */ + rem = (unsigned)(len2 % BASE); + sum1 = adler1 & 0xffff; + sum2 = rem * sum1; + MOD(sum2); + sum1 += (adler2 & 0xffff) + BASE - 1; + sum2 += ((adler1 >> 16) & 0xffff) + ((adler2 >> 16) & 0xffff) + BASE - rem; + if (sum1 >= BASE) sum1 -= BASE; + if (sum1 >= BASE) sum1 -= BASE; + if (sum2 >= (BASE << 1)) sum2 -= (BASE << 1); + if (sum2 >= BASE) sum2 -= BASE; + return sum1 | (sum2 << 16); +} + +/* ========================================================================= */ +uLong ZEXPORT adler32_combine(adler1, adler2, len2) + uLong adler1; + uLong adler2; + z_off_t len2; +{ + return adler32_combine_(adler1, adler2, len2); +} + +#if (defined(_LARGEFILE64_SOURCE)||(_FILE_OFFSET_BITS == 64)) +uLong ZEXPORT adler32_combine64(adler1, adler2, len2) + uLong adler1; + uLong adler2; + z_off64_t len2; +{ + return adler32_combine_(adler1, adler2, len2); +} +#endif /* (defined(_LARGEFILE64_SOURCE)||(_FILE_OFFSET_BITS == 64)) */ |