Module: Hyperll::Util

Included in:
HyperLogLogPlus, RegisterSet
Defined in:
lib/hyperll/util.rb

Constant Summary collapse

INT_MASK = 
0xFFFFFFFF
INTEGER_SIZE = 
32
POWERS_OF_TWO = 
0.upto(32).map { |i| 2**i }.freeze

Instance Method Summary collapse

Instance Method Details

#number_of_leading_zeros(x) ⇒ Object 



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# File 'lib/hyperll/util.rb', line 8

def number_of_leading_zeros(x)
  return 32 if x == 0

  n = 0
  if x <= 0x0000FFFF
    n += 16
    x *= POWERS_OF_TWO[16]
  end

  if x <= 0x00FFFFFF
    n += 8;
    x *= POWERS_OF_TWO[8]
  end

  if x <= 0x0FFFFFFF
    n += 4
    x *= POWERS_OF_TWO[4]
  end

  if x <= 0x3FFFFFFF
    n += 2
    x *= POWERS_OF_TWO[2]
  end

  if x <= 0x7FFFFFFF
    n += 1
  end

  n
end