diff options
author | marha <marha@users.sourceforge.net> | 2012-06-22 15:56:58 +0200 |
---|---|---|
committer | marha <marha@users.sourceforge.net> | 2012-06-22 15:56:58 +0200 |
commit | 66841fa144ddd72df67ab1ddf880ca508d4bc9e3 (patch) | |
tree | 7cf0afebcfa94bcc8b2046c85532efcf6b0f91d0 /zlib/adler32.c | |
parent | 1a68b7aceea62a76127f0fa13b3f127e37b2ec76 (diff) | |
parent | 7baa3d795c87c11550f1686488c968320428cbf9 (diff) | |
download | vcxsrv-66841fa144ddd72df67ab1ddf880ca508d4bc9e3.tar.gz vcxsrv-66841fa144ddd72df67ab1ddf880ca508d4bc9e3.tar.bz2 vcxsrv-66841fa144ddd72df67ab1ddf880ca508d4bc9e3.zip |
Merge remote-tracking branch 'origin/released'
Conflicts:
zlib/Makefile
Diffstat (limited to 'zlib/adler32.c')
-rw-r--r-- | zlib/adler32.c | 102 |
1 files changed, 66 insertions, 36 deletions
diff --git a/zlib/adler32.c b/zlib/adler32.c index 007ba2627..a868f073d 100644 --- a/zlib/adler32.c +++ b/zlib/adler32.c @@ -1,14 +1,17 @@ /* adler32.c -- compute the Adler-32 checksum of a data stream - * Copyright (C) 1995-2004 Mark Adler + * Copyright (C) 1995-2011 Mark Adler * For conditions of distribution and use, see copyright notice in zlib.h */ /* @(#) $Id$ */ -#define ZLIB_INTERNAL -#include "zlib.h" +#include "zutil.h" -#define BASE 65521UL /* largest prime smaller than 65536 */ +#define local static + +local uLong adler32_combine_ OF((uLong adler1, uLong adler2, z_off64_t len2)); + +#define BASE 65521 /* 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 */ @@ -18,39 +21,44 @@ #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 */ +/* use NO_DIVIDE if your processor does not do division in hardware -- + try it both ways to see which is faster */ #ifdef NO_DIVIDE -# define MOD(a) \ +/* note that this assumes BASE is 65521, where 65536 % 65521 == 15 + (thank you to John Reiser for pointing this out) */ +# define CHOP(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); \ + unsigned long tmp = a >> 16; \ + a &= 0xffffUL; \ + a += (tmp << 4) - tmp; \ + } while (0) +# define MOD28(a) \ + do { \ + CHOP(a); \ if (a >= BASE) a -= BASE; \ } while (0) -# define MOD4(a) \ +# define MOD(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); \ + CHOP(a); \ + MOD28(a); \ + } while (0) +# define MOD63(a) \ + do { /* this assumes a is not negative */ \ + z_off64_t tmp = a >> 32; \ + a &= 0xffffffffL; \ + a += (tmp << 8) - (tmp << 5) + tmp; \ + tmp = a >> 16; \ + a &= 0xffffL; \ + a += (tmp << 4) - tmp; \ + tmp = a >> 16; \ + a &= 0xffffL; \ + a += (tmp << 4) - tmp; \ if (a >= BASE) a -= BASE; \ } while (0) #else # define MOD(a) a %= BASE -# define MOD4(a) a %= BASE +# define MOD28(a) a %= BASE +# define MOD63(a) a %= BASE #endif /* ========================================================================= */ @@ -89,7 +97,7 @@ uLong ZEXPORT adler32(adler, buf, len) } if (adler >= BASE) adler -= BASE; - MOD4(sum2); /* only added so many BASE's */ + MOD28(sum2); /* only added so many BASE's */ return adler | (sum2 << 16); } @@ -125,25 +133,47 @@ uLong ZEXPORT adler32(adler, buf, len) } /* ========================================================================= */ -uLong ZEXPORT adler32_combine(adler1, adler2, len2) +local uLong adler32_combine_(adler1, adler2, len2) uLong adler1; uLong adler2; - z_off_t len2; + z_off64_t len2; { unsigned long sum1; unsigned long sum2; unsigned rem; + /* for negative len, return invalid adler32 as a clue for debugging */ + if (len2 < 0) + return 0xffffffffUL; + /* the derivation of this formula is left as an exercise for the reader */ - rem = (unsigned)(len2 % BASE); + MOD63(len2); /* assumes len2 >= 0 */ + rem = (unsigned)len2; 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; + 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); +} + +uLong ZEXPORT adler32_combine64(adler1, adler2, len2) + uLong adler1; + uLong adler2; + z_off64_t len2; +{ + return adler32_combine_(adler1, adler2, len2); +} |