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(zlib) Replace adler32

This commit is contained in:
twinaphex 2014-01-11 09:30:09 +01:00
parent 9c2a39f9c9
commit e53ff57166
1 changed files with 44 additions and 136 deletions
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170
deps/rzlib/adler32.c vendored
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@ -1,167 +1,75 @@
/* adler32.c -- compute the Adler-32 checksum of a data stream /* adler32.c -- compute the Adler-32 checksum of a data stream
* Copyright (C) 1995-2011 Mark Adler * Copyright (C) 1995-2003 Mark Adler
* For conditions of distribution and use, see copyright notice in zlib.h * For conditions of distribution and use, see copyright notice in zlib.h
*/ */
/* @(#) $Id$ */ /* @(#) $Id$ */
#define ZLIB_INTERNAL
#include <stdint.h>
#include <stddef.h>
#include "zutil.h" #include "zutil.h"
#define local static #define BASE 65521UL /* largest prime smaller than 65536 */
local uLong adler32_combine_ OF((uLong adler1, uLong adler2, z_off64_t len2));
#define BASE 65521 /* largest prime smaller than 65536 */
#define NMAX 5552 #define NMAX 5552
/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */ /* 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 DO1(buf,i) {s1 += buf[i]; s2 += s1;}
#define DO2(buf,i) DO1(buf,i); DO1(buf,i+1); #define DO2(buf,i) DO1(buf,i); DO1(buf,i+1);
#define DO4(buf,i) DO2(buf,i); DO2(buf,i+2); #define DO4(buf,i) DO2(buf,i); DO2(buf,i+2);
#define DO8(buf,i) DO4(buf,i); DO4(buf,i+4); #define DO8(buf,i) DO4(buf,i); DO4(buf,i+4);
#define DO16(buf) DO8(buf,0); DO8(buf,8); #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 */
#ifdef NO_DIVIDE #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) \
do { \
CHOP(a); \
if (a >= BASE) a -= BASE; \
} while (0)
# define MOD(a) \ # define MOD(a) \
do { \ do { \
CHOP(a); \ if (a >= (BASE << 16)) a -= (BASE << 16); \
MOD28(a); \ if (a >= (BASE << 15)) a -= (BASE << 15); \
} while (0) if (a >= (BASE << 14)) a -= (BASE << 14); \
# define MOD63(a) \ if (a >= (BASE << 13)) a -= (BASE << 13); \
do { /* this assumes a is not negative */ \ if (a >= (BASE << 12)) a -= (BASE << 12); \
z_off64_t tmp = a >> 32; \ if (a >= (BASE << 11)) a -= (BASE << 11); \
a &= 0xffffffffL; \ if (a >= (BASE << 10)) a -= (BASE << 10); \
a += (tmp << 8) - (tmp << 5) + tmp; \ if (a >= (BASE << 9)) a -= (BASE << 9); \
tmp = a >> 16; \ if (a >= (BASE << 8)) a -= (BASE << 8); \
a &= 0xffffL; \ if (a >= (BASE << 7)) a -= (BASE << 7); \
a += (tmp << 4) - tmp; \ if (a >= (BASE << 6)) a -= (BASE << 6); \
tmp = a >> 16; \ if (a >= (BASE << 5)) a -= (BASE << 5); \
a &= 0xffffL; \ if (a >= (BASE << 4)) a -= (BASE << 4); \
a += (tmp << 4) - tmp; \ 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; \ if (a >= BASE) a -= BASE; \
} while (0) } while (0)
#else #else
# define MOD(a) a %= BASE # define MOD(a) a %= BASE
# define MOD28(a) a %= BASE
# define MOD63(a) a %= BASE
#endif #endif
/* ========================================================================= */ /* ========================================================================= */
uLong ZEXPORT adler32(uLong adler, const Bytef *buf, uInt len) uLong adler32(uLong adler, const Bytef *buf, uInt len)
{ {
unsigned long sum2; uint32_t s1 = adler & 0xffff;
unsigned n; uint32_t s2 = (adler >> 16) & 0xffff;
int k;
/* split Adler-32 into component sums */ if (buf == NULL)
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; return 1L;
/* in case short lengths are provided, keep it somewhat fast */ while (len > 0) {
if (len < 16) { k = len < NMAX ? (int)len : NMAX;
while (len--) { len -= k;
adler += *buf++; while (k >= 16) {
sum2 += adler;
}
if (adler >= BASE)
adler -= BASE;
MOD28(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); DO16(buf);
buf += 16; buf += 16;
k -= 16;
} }
while (len--) { if (k != 0) do {
adler += *buf++; s1 += *buf++;
sum2 += adler; s2 += s1;
} while (--k);
MOD(s1);
MOD(s2);
} }
MOD(adler); return (s2 << 16) | s1;
MOD(sum2);
} }
/* return recombined sums */
return adler | (sum2 << 16);
}
/* ========================================================================= */
local uLong adler32_combine_(uLong adler1, uLong adler2, 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 */
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;
return sum1 | (sum2 << 16);
}
/* ========================================================================= */
uLong adler32_combine(uLong adler1, uLong adler2, z_off_t len2)
{
return adler32_combine_(adler1, adler2, len2);
}
uLong adler32_combine64(uLong adler1, uLong adler2, z_off64_t len2)
{
return adler32_combine_(adler1, adler2, len2);
}