* bignum.c (rb_big_mul): faster multiplication by Karatsuba method and

  twice faster square than normal multiplication.

* random.c (rb_rand_internal): used by Bignum#*.

* test/ruby/test_bignum.rb: add some tests for above.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@20733 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 20 insertions, 0 deletions

diff --git a/test/ruby/test_bignum.rb b/test/ruby/test_bignum.rb
index b60622fb17..29fda85572 100644
--- a/test/ruby/test_bignum.rb
+++ b/test/ruby/test_bignum.rb
@@ -200,11 +200,24 @@ class TestBignum < Test::Unit::TestCase
 
   def test_sub
     assert_equal(-T31, T32 - (T32 + T31))
+    x = 2**100
+    assert_equal(1, (x+2) - (x+1))
+    assert_equal(-1, (x+1) - (x+2))
+    assert_equal(0, (2**100) - (2.0**100))
+    o = Object.new
+    def o.coerce(x); [2**100+2, x]; end
+    assert_equal(1, (2**100+1) - o)
   end
 
   def test_plus
     assert_equal(T32.to_f, T32P + 1.0)
     assert_raise(TypeError) { T32 + "foo" }
+    assert_equal(1267651809154049016125877911552, (2**100) + (2**80))
+    assert_equal(1267651809154049016125877911552, (2**80) + (2**100))
+    assert_equal(2**101, (2**100) + (2.0**100))
+    o = Object.new
+    def o.coerce(x); [2**80, x]; end
+    assert_equal(1267651809154049016125877911552, (2**100) + o)
   end
 
   def test_minus
@@ -215,6 +228,13 @@ class TestBignum < Test::Unit::TestCase
   def test_mul
     assert_equal(T32.to_f, T32 * 1.0)
     assert_raise(TypeError) { T32 * "foo" }
+    o = Object.new
+    def o.coerce(x); [2**100, x]; end
+    assert_equal(2**180, (2**80) * o)
+  end
+
+  def test_mul_balance
+    assert_equal(3**7000, (3**5000) * (3**2000))
   end
 
   def test_divrem