1 // lookup3 by Bob Jekins, code is public domain. 2 3 #include "Platform.h" 4 5 #define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k)))) 6 7 #define mix(a,b,c) \ 8 { \ 9 a -= c; a ^= rot(c, 4); c += b; \ 10 b -= a; b ^= rot(a, 6); a += c; \ 11 c -= b; c ^= rot(b, 8); b += a; \ 12 a -= c; a ^= rot(c,16); c += b; \ 13 b -= a; b ^= rot(a,19); a += c; \ 14 c -= b; c ^= rot(b, 4); b += a; \ 15 } 16 17 #define final(a,b,c) \ 18 { \ 19 c ^= b; c -= rot(b,14); \ 20 a ^= c; a -= rot(c,11); \ 21 b ^= a; b -= rot(a,25); \ 22 c ^= b; c -= rot(b,16); \ 23 a ^= c; a -= rot(c,4); \ 24 b ^= a; b -= rot(a,14); \ 25 c ^= b; c -= rot(b,24); \ 26 } 27 28 uint32_t lookup3 ( const void * key, int length, uint32_t initval ) 29 { 30 uint32_t a,b,c; /* internal state */ 31 32 a = b = c = 0xdeadbeef + ((uint32_t)length) + initval; 33 34 const uint32_t *k = (const uint32_t *)key; /* read 32-bit chunks */ 35 36 /*------ all but last block: aligned reads and affect 32 bits of (a,b,c) */ 37 while (length > 12) 38 { 39 a += k[0]; 40 b += k[1]; 41 c += k[2]; 42 mix(a,b,c); 43 length -= 12; 44 k += 3; 45 } 46 47 switch(length) 48 { 49 case 12: c+=k[2]; b+=k[1]; a+=k[0]; break; 50 case 11: c+=k[2]&0xffffff; b+=k[1]; a+=k[0]; break; 51 case 10: c+=k[2]&0xffff; b+=k[1]; a+=k[0]; break; 52 case 9 : c+=k[2]&0xff; b+=k[1]; a+=k[0]; break; 53 case 8 : b+=k[1]; a+=k[0]; break; 54 case 7 : b+=k[1]&0xffffff; a+=k[0]; break; 55 case 6 : b+=k[1]&0xffff; a+=k[0]; break; 56 case 5 : b+=k[1]&0xff; a+=k[0]; break; 57 case 4 : a+=k[0]; break; 58 case 3 : a+=k[0]&0xffffff; break; 59 case 2 : a+=k[0]&0xffff; break; 60 case 1 : a+=k[0]&0xff; break; 61 case 0 : { return c; } /* zero length strings require no mixing */ 62 } 63 64 final(a,b,c); 65 66 return c; 67 } 68 69 void lookup3_test ( const void * key, int len, uint32_t seed, void * out ) 70 { 71 *(uint32_t*)out = lookup3(key,len,seed); 72 } 73
