/*
 * MurmurHash2A (C) Austin Appleby
 */

#include "murmurhash2a.h"

#define mmix(h,k) { k *= m; k ^= k >> r; k *= m; h *= m; h ^= k; }

static uint32_t
murmur_hash_process2a(const char *key, uint32_t length, uint32_t seed)
{
  const uint32_t m = MURMURHASH_MAGIC;
  const uint8_t r = 24;
  uint32_t h, k, t, l;
  const unsigned char *data = (const unsigned char *) key;

  l = length;
  h = seed;

  while (4 <= length) {
    k = *(uint32_t*)data;
    mmix(h,k);
    data += 4;
    length -= 4;
  }

  t = 0;
  switch (length) {
    case 3: t ^= data[2] << 16;
    case 2: t ^= data[1] << 8;
    case 1: t ^= data[0];
  }

  mmix(h,t);
  mmix(h,l);

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

  return h;
}

VALUE
murmur2a_finish(VALUE self)
{
  uint8_t digest[4];
  uint64_t h;

  h = _murmur_finish32(self, murmur_hash_process2a);
  assign_by_endian_32(digest, h);
  return rb_str_new((const char*) digest, 4);
}

VALUE
murmur2a_s_digest(int argc, VALUE *argv, VALUE klass)
{
  uint8_t digest[4];
  uint32_t h;
  h = _murmur_s_digest32(argc, argv, klass, murmur_hash_process2a);
  assign_by_endian_32(digest, h);
  return rb_str_new((const char*) digest, 4);
}

VALUE
murmur2a_s_rawdigest(int argc, VALUE *argv, VALUE klass)
{
  return ULL2NUM(_murmur_s_digest32(argc, argv, klass, murmur_hash_process2a));
}