Module: MurmurHash3::PureRuby128

Extended by:
PureRuby128
Included in:
PureRuby128
Defined in:
lib/murmurhash3/pure_ruby.rb

Constant Summary collapse

MASK64 = 
0xffff_ffff_ffff_ffff
C1_128 = 
0x87c37b91_114253d5
C2_128 = 
0x4cf5ad43_2745937f

Instance Method Summary collapse

Instance Method Details

#murmur3_128__mmix1(k1) ⇒ Object 



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# File 'lib/murmurhash3/pure_ruby.rb', line 83

def murmur3_128__mmix1(k1)
  k1 = (k1 * C1_128) & MASK64
  k1 = murmur3_128_rotl(k1, 31)
  (k1 * C2_128) & MASK64
end

#murmur3_128__mmix2(k2) ⇒ Object 



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# File 'lib/murmurhash3/pure_ruby.rb', line 89

def murmur3_128__mmix2(k2)
  k2 = (k2 * C2_128) & MASK64
  k2 = murmur3_128_rotl(k2, 33)
  (k2 * C1_128) & MASK64
end

#murmur3_128_fmix(h) ⇒ Object 



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# File 'lib/murmurhash3/pure_ruby.rb', line 72

def murmur3_128_fmix(h)
  h &= MASK64
  h ^= h >> 33
  h = (h * 0xff51afd7_ed558ccd) & MASK64
  h ^= h >> 33
  h = (h * 0xc4ceb9fe_1a85ec53) & MASK64
  h ^ (h >> 33)
end

#murmur3_128_int32_hash(i, seed = 0) ⇒ Object 



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# File 'lib/murmurhash3/pure_ruby.rb', line 139

def murmur3_128_int32_hash(i, seed=0)
  str_hash([i].pack("V"), seed)
end

#murmur3_128_int64_hash(i, seed = 0) ⇒ Object 



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# File 'lib/murmurhash3/pure_ruby.rb', line 143

def murmur3_128_int64_hash(i, seed=0)
  str_hash([i].pack("Q<"), seed)
end

#murmur3_128_rotl(x, r) ⇒ Object 



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# File 'lib/murmurhash3/pure_ruby.rb', line 68

def murmur3_128_rotl(x, r)
  ((x << r) | (x >> (64 - r))) & MASK64
end

#murmur3_128_str_hash(str, seed = 0) ⇒ Object 



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# File 'lib/murmurhash3/pure_ruby.rb', line 95

def murmur3_128_str_hash(str, seed=0)
  h1 = h2 = seed
  fast_part = ((str.bytesize / 16) * 16)
  numbers = str.byteslice(0, fast_part).unpack('Q<*')
  tail = str.byteslice(fast_part, str.bytesize - fast_part).unpack('C*')

  numbers.each_slice(2) do |k1, k2|
    h1 ^= murmur3_128__mmix1(k1)
    h1 = murmur3_128_rotl(h1, 27)
    h1 = (h1 + h2) & MASK64
    h1 = (h1*5 + 0x52dce729) & MASK64
    h2 ^= murmur3_128__mmix2(k2)
    h2 = murmur3_128_rotl(h2, 31)
    h2 = (h1 + h2) & MASK64
    h2 = (h2*5 + 0x38495ab5) & MASK64
  end

  unless tail.empty?
    if tail.size > 8
      k2 = 0
      tail[8,8].reverse_each do |c2|
        k2 = (k2 << 8) | c2
      end
      h2 ^= murmur3_128__mmix2(k2)
    end
    k1 = 0
    tail[0,8].reverse_each do |c1|
      k1 = (k1 << 8) | c1
    end
    h1 ^= murmur3_128__mmix1(k1)
  end

  h1 ^= str.bytesize
  h2 ^= str.bytesize
  h1 = (h1 + h2) & MASK64
  h2 = (h1 + h2) & MASK64
  h1 = murmur3_128_fmix(h1)
  h2 = murmur3_128_fmix(h2)

  h1 = (h1 + h2) & MASK64
  h2 = (h1 + h2) & MASK64
  [h1 & 0xffffffff, h1 >> 32, h2 & 0xffffffff, h2 >> 32]
end