// lookup3 by Bob Jekins, code is public domain. | |
#include "Platform.h" | |
#define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k)))) | |
#define mix(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 final(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 lookup3 ( const void * key, int length, uint32_t initval ) | |
{ | |
uint32_t a,b,c; /* internal state */ | |
a = b = c = 0xdeadbeef + ((uint32_t)length) + initval; | |
const uint32_t *k = (const uint32_t *)key; /* 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]; | |
mix(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 */ | |
} | |
final(a,b,c); | |
return c; | |
} | |
void lookup3_test ( const void * key, int len, uint32_t seed, void * out ) | |
{ | |
*(uint32_t*)out = lookup3(key,len,seed); | |
} |