diff options
Diffstat (limited to 'cpan/Compress-Raw-Zlib/zlib-src/adler32.c')
-rw-r--r-- | cpan/Compress-Raw-Zlib/zlib-src/adler32.c | 68 |
1 files changed, 29 insertions, 39 deletions
diff --git a/cpan/Compress-Raw-Zlib/zlib-src/adler32.c b/cpan/Compress-Raw-Zlib/zlib-src/adler32.c index 82a84ceed2..9b0c8355e2 100644 --- a/cpan/Compress-Raw-Zlib/zlib-src/adler32.c +++ b/cpan/Compress-Raw-Zlib/zlib-src/adler32.c @@ -1,5 +1,5 @@ /* adler32.c -- compute the Adler-32 checksum of a data stream - * Copyright (C) 1995-2011 Mark Adler + * Copyright (C) 1995-2007 Mark Adler * For conditions of distribution and use, see copyright notice in zlib.h */ @@ -9,9 +9,9 @@ #define local static -local uLong adler32_combine_ OF((uLong adler1, uLong adler2, z_off64_t len2)); +local uLong adler32_combine_(uLong adler1, uLong adler2, z_off64_t len2); -#define BASE 65521 /* largest prime smaller than 65536 */ +#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 */ @@ -21,44 +21,39 @@ local uLong adler32_combine_ OF((uLong adler1, uLong adler2, z_off64_t len2)); #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 -- - try it both ways to see which is faster */ +/* use NO_DIVIDE if your processor does not do division in hardware */ #ifdef NO_DIVIDE -/* note that this assumes BASE is 65521, where 65536 % 65521 == 15 - (thank you to John Reiser for pointing this out) */ -# define CHOP(a) \ - do { \ - unsigned long tmp = a >> 16; \ - a &= 0xffffUL; \ - a += (tmp << 4) - tmp; \ - } while (0) -# define MOD28(a) \ +# define MOD(a) \ do { \ - CHOP(a); \ + 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 MOD(a) \ +# define MOD4(a) \ do { \ - 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 << 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 MOD28(a) a %= BASE -# define MOD63(a) a %= BASE +# define MOD4(a) a %= BASE #endif /* ========================================================================= */ @@ -97,7 +92,7 @@ uLong ZEXPORT adler32( } if (adler >= BASE) adler -= BASE; - MOD28(sum2); /* only added so many BASE's */ + MOD4(sum2); /* only added so many BASE's */ return adler | (sum2 << 16); } @@ -142,13 +137,8 @@ local uLong adler32_combine_( 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 */ - MOD63(len2); /* assumes len2 >= 0 */ - rem = (unsigned)len2; + rem = (unsigned)(len2 % BASE); sum1 = adler1 & 0xffff; sum2 = rem * sum1; MOD(sum2); |