module BitsCount::Primitive

Constants

UNPACK_PATTERN
WORDBITS

Public Class Methods

population_count_int32(i) click to toggle source
# File lib/bits_count/primitive.rb, line 8
def population_count_int32(i)
  i = i - ((i >> 1) & 0x55555555)
  i = (i & 0x33333333) + ((i >> 2) & 0x33333333)
  i = (i + (i >> 4)) & 0x0F0F0F0F
  i = i + (i >> 8)
  i = i + (i >> 16)
  i & 0x0000003F
end
population_count_map(i) click to toggle source
# File lib/bits_count/primitive.rb, line 22
def population_count_map(i)
  WORDBITS[i&0xFFFF] + WORDBITS[i>>16]
end
population_count_str(s) click to toggle source
# File lib/bits_count/primitive.rb, line 18
def population_count_str(s)
  s.unpack(UNPACK_PATTERN).first.count(?1)
end