Class: AmplitudeExperiment::Evaluation::Murmur3

Inherits:
Object
  • Object
show all
Defined in:
lib/experiment/evaluation/murmur3.rb

Constant Summary collapse

C1_32 = 
-0x3361d2af
C2_32 = 
0x1b873593
R1_32 = 
15
R2_32 = 
13
M_32 = 
5
N_32 = 
-0x19ab949c

Class Method Summary collapse

Class Method Details

.hash32x86(input, seed = 0) ⇒ Object 



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# File 'lib/experiment/evaluation/murmur3.rb', line 15

def hash32x86(input, seed = 0)
  data = string_to_utf8_bytes(input)
  length = data.length
  n_blocks = length >> 2
  hash = seed

  # Process body
  n_blocks.times do |i|
    index = i << 2
    k = read_int_le(data, index)
    hash = mix32(k, hash)
  end

  # Process tail
  index = n_blocks << 2
  k1 = 0

  case length - index
  when 3
    k1 ^= data[index + 2] << 16
    k1 ^= data[index + 1] << 8
    k1 ^= data[index]
    k1 = (k1 * C1_32) & 0xffffffff
    k1 = rotate_left(k1, R1_32)
    k1 = (k1 * C2_32) & 0xffffffff
    hash ^= k1
  when 2
    k1 ^= data[index + 1] << 8
    k1 ^= data[index]
    k1 = (k1 * C1_32) & 0xffffffff
    k1 = rotate_left(k1, R1_32)
    k1 = (k1 * C2_32) & 0xffffffff
    hash ^= k1
  when 1
    k1 ^= data[index]
    k1 = (k1 * C1_32) & 0xffffffff
    k1 = rotate_left(k1, R1_32)
    k1 = (k1 * C2_32) & 0xffffffff
    hash ^= k1
  end

  hash ^= length
  fmix32(hash) & 0xffffffff
end