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path: root/src/hash/murmur.c
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#include "../crypto.h"
#include <stdio.h>
#include <stdint.h>

uint32_t murmur1_32(uint8_t* in, size_t len, uint32_t seed){
  uint32_t m = 0xc6a4a793;
  uint32_t hash = seed ^ (len * m);

  for(;len >= 4; len-=4){
    hash+=*(uint32_t*)in;
    hash*=m;
    hash^=hash >> 16;

    in+=4;
  }

  switch(len){
    case 3:
      hash+=in[2]<<16;
    case 2:
      hash+=in[1]<<8;
    case 1:
      hash+=in[0];
      hash*=m;
      hash^=hash>>16;
      break;
  }

  hash*=m;
  hash^=hash>>10;
  hash*=m;
  hash^=hash>>17;

  return hash;
}

uint32_t murmur2_32(uint8_t* in, size_t len, uint32_t seed){
  uint32_t m = 0x5bd1e995;
  uint32_t hash = seed ^ len;

  for(;len >= 4; len-=4){
    uint32_t k = *(uint32_t*)in;

    k*=m;
    k^=k>>24;
    k*=m;

    hash*=m;
    hash^=k;

    in+=4;
  }

  switch(len){
    case 3:
      hash+=in[2]<<16;
    case 2:
      hash+=in[1]<<8;
    case 1:
      hash+=in[0];
      hash*=m;
      break;
  }

  hash^=hash>>13;
  hash*=m;
  hash^=hash>>15;

  return hash;
}

int l_murmur1_32(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 = murmur1_32(a, len, seed);
  sprintf(digest,"%08lx",u);
  lua_pushstring(L, digest);
  return 1;
}

int l_murmur2_32(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 = murmur2_32(a, len, seed);
  sprintf(digest,"%08lx",u);
  lua_pushstring(L, digest);
  return 1;
}