test/-ext-/bignum/test_mul.rb


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require 'test/unit'
require "-test-/bignum"

class TestBignum < Test::Unit::TestCase
  class TestMul < Test::Unit::TestCase

    SIZEOF_BDIGITS = Bignum::SIZEOF_BDIGITS
    BITSPERDIG = Bignum::BITSPERDIG

    def test_mul_normal
      x = (1 << BITSPERDIG) | 1
      y = (1 << BITSPERDIG) | 1
      z = (1 << (BITSPERDIG*2)) | (2 << BITSPERDIG) | 1
      assert_equal(z, x.big_mul_normal(y))
    end

    def test_mul_normal_zero_in_x
      x = (1 << (2*BITSPERDIG)) | 1
      y = (1 << BITSPERDIG) | 1
      z = (1 << (BITSPERDIG*3)) | (1 << (BITSPERDIG*2)) | (1 << BITSPERDIG) | 1
      assert_equal(z, x.big_mul_normal(y))
    end

    def test_mul_normal_zero_in_y
      x = (1 << BITSPERDIG) | 1
      y = (1 << (2*BITSPERDIG)) | 1
      z = (1 << (BITSPERDIG*3)) | (1 << (BITSPERDIG*2)) | (1 << BITSPERDIG) | 1
      assert_equal(z, x.big_mul_normal(y))
    end

    def test_mul_normal_max_max
      x = (1 << (2*BITSPERDIG)) - 1
      y = (1 << (2*BITSPERDIG)) - 1
      z = (1 << (4*BITSPERDIG)) - (1 << (2*BITSPERDIG+1)) + 1
      assert_equal(z, x.big_mul_normal(y))
    end

    def test_mul_balance
      x = (1 << BITSPERDIG) | 1
      y = (1 << BITSPERDIG) | 1
      z = (1 << (BITSPERDIG*2)) | (2 << BITSPERDIG) | 1
      assert_equal(z, x.big_mul_balance(y))
    end

    def test_mul_karatsuba
      x = (1 << BITSPERDIG) | 1
      y = (1 << BITSPERDIG) | 1
      z = (1 << (BITSPERDIG*2)) | (2 << BITSPERDIG) | 1
      assert_equal(z, x.big_mul_karatsuba(y))
    end

  end
end