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#include "../util.h"
#include "../crypto.h"
#include <stdio.h>
#include <stdint.h>
//almost entirely taken from https://github.com/ztanml/fast-hash/blob/master/fasthash.c
#define mix(h) ({ \
(h) ^= (h) >> 23; \
(h) *= 0x2127599bf4325c37ULL; \
(h) ^= (h) >> 47; })
uint64_t fasthash64(uint8_t* in, size_t len, uint64_t seed){
uint64_t m = 0x880355f21e6d1965ULL;
uint64_t hash = seed ^ (len * m);
uint64_t* data = (uint64_t*)in;
uint64_t v;
for(;len >= 8; len-=8){
v=*data++;
hash^=mix(v);
hash*=m;
in+=4;
}
uint8_t* data2 = (uint8_t*)data;
v=0;
switch (len & 7) {
case 7:
v ^= (uint64_t)data2[6] << 48;
case 6:
v ^= (uint64_t)data2[5] << 40;
case 5:
v ^= (uint64_t)data2[4] << 32;
case 4:
v ^= (uint64_t)data2[3] << 24;
case 3:
v ^= (uint64_t)data2[2] << 16;
case 2:
v ^= (uint64_t)data2[1] << 8;
case 1:
v ^= (uint64_t)data2[0];
hash ^= mix(v);
hash *= m;
}
return mix(hash);
}
uint32_t fasthash32(uint8_t *buf, size_t len, uint32_t seed){
uint64_t hash = fasthash64(buf, len, seed);
return hash - (hash >> 32);
}
int l_fasthash64(lua_State* L){
size_t len = 0;
uint8_t* a = (uint8_t*)luaL_checklstring(L, 1, &len);
int argv = lua_gettop(L);
uint64_t seed = 0;
if(argv > 1) seed = luaL_checkinteger(L, 2);
char digest[64];
uint64_t u = fasthash64(a, len, seed);
sprintf(digest,"%08lx",u);
lua_pushstring(L, digest);
return 1;
}
int l_fasthash32(lua_State* L){
size_t len = 0;
uint8_t* a = (uint8_t*)luaL_checklstring(L, 1, &len);
int argv = lua_gettop(L);
uint32_t seed = 0;
if(argv > 1) seed = luaL_checkinteger(L, 2);
char digest[32];
uint32_t u = fasthash32(a, len, seed);
sprintf(digest,"%04x",u);
lua_pushstring(L, digest);
return 1;
}
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