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/*
dbx_tree: tree database driver for Miranda IM
Copyright 2007-2010 Michael "Protogenes" Kunz,
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include "Hash.h"
/// lookup3, by Bob Jenkins, May 2006, Public Domain.
#define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k))))
#define HASHmix(a,b,c) \
{ \
a -= c; a ^= rot(c, 4); c += b; \
b -= a; b ^= rot(a, 6); a += c; \
c -= b; c ^= rot(b, 8); b += a; \
a -= c; a ^= rot(c,16); c += b; \
b -= a; b ^= rot(a,19); a += c; \
c -= b; c ^= rot(b, 4); b += a; \
}
#define HASHfinal(a,b,c) \
{ \
c ^= b; c -= rot(b,14); \
a ^= c; a -= rot(c,11); \
b ^= a; b -= rot(a,25); \
c ^= b; c -= rot(b,16); \
a ^= c; a -= rot(c, 4); \
b ^= a; b -= rot(a,14); \
c ^= b; c -= rot(b,24); \
}
uint32_t Hash(const void * Data, uint32_t Length)
{
register uint32_t a,b,c; // internal state
union { const void *ptr; uint32_t i; } u; // needed for Mac Powerbook G4
// Set up the internal state
a = b = c = 0xdeadbeef + Length; // + initval = 0
u.ptr = Data;
if ((u.i & 0x3) == 0)
{
const uint32_t *k = (const uint32_t *)Data; // read 32-bit chunks
// all but last block: aligned reads and affect 32 bits of (a,b,c)
while (Length > 12)
{
a += k[0];
b += k[1];
c += k[2];
HASHmix(a,b,c);
Length -= 12;
k += 3;
}
switch(Length)
{
case 12: c += k[2]; b += k[1]; a += k[0]; break;
case 11: c += k[2] & 0xffffff; b += k[1]; a += k[0]; break;
case 10: c += k[2] & 0xffff; b += k[1]; a += k[0]; break;
case 9 : c += k[2] & 0xff; b += k[1]; a += k[0]; break;
case 8 : b += k[1]; a += k[0]; break;
case 7 : b += k[1] & 0xffffff; a += k[0]; break;
case 6 : b += k[1] & 0xffff; a += k[0]; break;
case 5 : b += k[1] & 0xff; a += k[0]; break;
case 4 : a += k[0]; break;
case 3 : a += k[0] & 0xffffff; break;
case 2 : a += k[0] & 0xffff; break;
case 1 : a += k[0] & 0xff; break;
case 0 : return c; // zero length strings require no mixing
}
} else if ((u.i & 0x1) == 0) {
const uint16_t *k = (const uint16_t *)Data; /* read 16-bit chunks */
const uint8_t *k8;
// all but last block: aligned reads and different mixing
while (Length > 12)
{
a += k[0] + (((uint32_t)k[1]) << 16);
b += k[2] + (((uint32_t)k[3]) << 16);
c += k[4] + (((uint32_t)k[5]) << 16);
HASHmix(a,b,c);
Length -= 12;
k += 6;
}
// handle the last (probably partial) block
k8 = (const uint8_t *)k;
switch(Length)
{
case 12: c += k[4] + (((uint32_t)k[5]) << 16);
b += k[2] + (((uint32_t)k[3]) << 16);
a += k[0] + (((uint32_t)k[1]) << 16);
break;
case 11: c += ((uint32_t)k8[10]) << 16; // fall through
case 10: c += k[4];
b += k[2] + (((uint32_t)k[3]) << 16);
a += k[0] + (((uint32_t)k[1]) << 16);
break;
case 9 : c += k8[8]; // fall through
case 8 : b += k[2] + (((uint32_t)k[3]) << 16);
a += k[0] + (((uint32_t)k[1]) << 16);
break;
case 7 : b += ((uint32_t)k8[6]) << 16; // fall through
case 6 : b += k[2];
a += k[0] + (((uint32_t)k[1]) << 16);
break;
case 5 : b += k8[4]; // fall through
case 4 : a += k[0] + (((uint32_t)k[1]) << 16);
break;
case 3 : a += ((uint32_t)k8[2]) << 16; // fall through
case 2 : a += k[0];
break;
case 1 : a += k8[0];
break;
case 0 : return c; // zero length requires no mixing
}
} else { // need to read the key one byte at a time
const uint8_t *k = (const uint8_t *)Data;
// all but the last block: affect some 32 bits of (a,b,c)
while (Length > 12)
{
a += k[0];
a += ((uint32_t)k[1] ) << 8;
a += ((uint32_t)k[2] ) << 16;
a += ((uint32_t)k[3] ) << 24;
b += k[4];
b += ((uint32_t)k[5] ) << 8;
b += ((uint32_t)k[6] ) << 16;
b += ((uint32_t)k[7] ) << 24;
c += k[8];
c += ((uint32_t)k[9] ) << 8;
c += ((uint32_t)k[10]) << 16;
c += ((uint32_t)k[11]) << 24;
HASHmix(a,b,c);
Length -= 12;
k += 12;
}
// last block: affect all 32 bits of (c)
switch(Length) // all the case statements fall through
{
case 12: c += ((uint32_t)k[11]) << 24;
case 11: c += ((uint32_t)k[10]) << 16;
case 10: c += ((uint32_t)k[9] ) << 8;
case 9 : c += k[8];
case 8 : b += ((uint32_t)k[7] ) << 24;
case 7 : b += ((uint32_t)k[6] ) << 16;
case 6 : b += ((uint32_t)k[5] ) << 8;
case 5 : b += k[4];
case 4 : a += ((uint32_t)k[3] ) << 24;
case 3 : a += ((uint32_t)k[2] ) << 16;
case 2 : a += ((uint32_t)k[1] ) << 8;
case 1 : a += k[0];
break;
case 0 : return c;
}
}
HASHfinal(a,b,c);
return c;
}
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