view release on metacpan or  search on metacpan

JumpHash.xs  view on Meta::CPAN

  for ( ; in != end; in += 8 )
  {
    m = U8TO64_LE( in );
    v3 ^= m;
    SIPROUND;
    SIPROUND;
    v0 ^= m;
  }

  switch( left )
  {
  case 7: b |= ( ( uint64_t )in[ 6] )  << 48;
  case 6: b |= ( ( uint64_t )in[ 5] )  << 40;
  case 5: b |= ( ( uint64_t )in[ 4] )  << 32;
  case 4: b |= ( ( uint64_t )in[ 3] )  << 24;
  case 3: b |= ( ( uint64_t )in[ 2] )  << 16;
  case 2: b |= ( ( uint64_t )in[ 1] )  <<  8;
  case 1: b |= ( ( uint64_t )in[ 0] ); break;
  case 0: break;
  }

  v3 ^= b;
  SIPROUND;
  SIPROUND;
  v0 ^= b;

  v2 ^= 0xff;
  SIPROUND;
  SIPROUND;
  SIPROUND;
  SIPROUND;
  b = v0 ^ v1 ^ v2  ^ v3;
  return b;
  /*return (U32)(b & U32_MAX);*/
}

int32_t
JumpConsistentHash(uint64_t key, int32_t num_buckets)
{
  int64_t b = 1;
  int64_t j = 0;

  while (j < num_buckets) {
    b = j;
    key = key * 2862933555777941757ULL + 1;
    j = (b + 1) * ((double)(1LL << 31) / (double)((key >> 33) + 1));
  }

  return b;
}


MODULE = Algorithm::ConsistentHash::JumpHash		PACKAGE = Algorithm::ConsistentHash::JumpHash
PROTOTYPES: DISABLE


int32_t
jumphash_numeric(uint64_t key, int32_t num_buckets)
  CODE:
    RETVAL = JumpConsistentHash(key, num_buckets);
  OUTPUT: RETVAL

int32_t
jumphash_siphash(SV *str, uint64_t num_buckets)
  CODE:
    {
      STRLEN len;
      /* FIXME */
      const char * strval = SvPVbyte(str, len);
      const uint64_t hashval = siphash_2_4_from_perl(strval, len);
      RETVAL = JumpConsistentHash(hashval, num_buckets);
    }
  OUTPUT: RETVAL