Class: Deacon::RandomGenerator

Inherits:
Generator show all
Defined in:
lib/deacon/random_generator.rb

Constant Summary collapse

MASK = 
0x1ffffff

Constants inherited from Generator

Generator::DEFAULT_DATA_DIR, Generator::GIVEN_FEMALE_NAMES_FILE, Generator::GIVEN_MALE_NAMES_FILE, Generator::RECORD_LENGTH_GIVEN, Generator::RECORD_LENGTH_SURNAME, Generator::SURNAMES_FILE

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Generator

#initialize

Constructor Details

This class inherits a constructor from Deacon::Generator

Class Method Details

.random_initial_seed ⇒ Object 



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# File 'lib/deacon/random_generator.rb', line 31

def self.random_initial_seed
  rand(MASK - 2) + 1
end

Instance Method Details

#generate(seed = Time.now.utc.to_i, test_uniquess = true) ⇒ Object 



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# File 'lib/deacon/random_generator.rb', line 16

def generate(seed = Time.now.utc.to_i, test_uniquess = true)
  return [] if seed.nil? || seed == 0
  index = seed
  loop do
    index = next_lfsr25(index)
    break if !test_uniquess || unique?(seed, index)
  end
  given_file = (index & 0x1000000) == 0 ? GIVEN_MALE_NAMES_FILE : GIVEN_FEMALE_NAMES_FILE
  givenname_ix = (index & 0xff0000) >> 16
  surnname_ix = index & 0xffff
  firstname = find_name(givenname_ix, data_file(given_file), RECORD_LENGTH_GIVEN)
  surname = find_name(surnname_ix, data_file(SURNAMES_FILE), RECORD_LENGTH_SURNAME)
  [index, firstname, surname]
end

#next_lfsr25(seed) ⇒ Object

Fibonacci linear feedback shift register with x^25 + x^24 + x^23 + x^22 + 1 poly

Raises:

  • (ArgumentError) 


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# File 'lib/deacon/random_generator.rb', line 6

def next_lfsr25(seed)
  i = 1
  i = (seed + 1) & MASK
  raise ArgumentError, "Seed #{seed} out of bounds" if seed && i == 0
  i = (seed + 1) & MASK while i == 0
  i = (i >> 1) | ((i[0]^i[1]^i[2]^i[3]) << 0x18)
  i = (i >> 1) | ((i[0]^i[1]^i[2]^i[3]) << 0x18) while i > MASK
  i - 1
end