ref: 36ba74a2b6f427b46e50abebe6bc8564524ec29b
dir: /llt/hashing.c/
/* Hashing */ #ifdef __plan9__ #include <u.h> #include <libc.h> #else #include <stdlib.h> #include <stdio.h> #include <math.h> #endif #include "dtypes.h" #include "utils.h" #include "hashing.h" #include "timefuncs.h" #include "ios.h" #include "random.h" uint_t nextipow2(uint_t i) { if (i==0) return 1; if ((i&(i-1))==0) return i; if (i&TOP_BIT) return TOP_BIT; // repeatedly clear bottom bit while (i&(i-1)) i = i&(i-1); return i<<1; } u_int32_t int32hash(u_int32_t a) { a = (a+0x7ed55d16) + (a<<12); a = (a^0xc761c23c) ^ (a>>19); a = (a+0x165667b1) + (a<<5); a = (a+0xd3a2646c) ^ (a<<9); a = (a+0xfd7046c5) + (a<<3); a = (a^0xb55a4f09) ^ (a>>16); return a; } u_int64_t int64hash(u_int64_t key) { key = (~key) + (key << 21); // key = (key << 21) - key - 1; key = key ^ (key >> 24); key = (key + (key << 3)) + (key << 8); // key * 265 key = key ^ (key >> 14); key = (key + (key << 2)) + (key << 4); // key * 21 key = key ^ (key >> 28); key = key + (key << 31); return key; } u_int32_t int64to32hash(u_int64_t key) { key = (~key) + (key << 18); // key = (key << 18) - key - 1; key = key ^ (key >> 31); key = key * 21; // key = (key + (key << 2)) + (key << 4); key = key ^ (key >> 11); key = key + (key << 6); key = key ^ (key >> 22); return (u_int32_t)key; } #include "lookup3.c" u_int64_t memhash(const char* buf, size_t n) { u_int32_t c=0xcafe8881, b=0x4d6a087c; hashlittle2(buf, n, &c, &b); return (u_int64_t)c | (((u_int64_t)b)<<32); } u_int32_t memhash32(const char* buf, size_t n) { u_int32_t c=0xcafe8881, b=0x4d6a087c; hashlittle2(buf, n, &c, &b); return c; }