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require_relative '../../spec_helper'
describe "Integer#bit_length" do
context "fixnum" do
it "returns the position of the leftmost bit of a positive number" do
0.bit_length.should == 0
1.bit_length.should == 1
2.bit_length.should == 2
3.bit_length.should == 2
4.bit_length.should == 3
n = fixnum_max.bit_length
fixnum_max[n].should == 0
fixnum_max[n - 1].should == 1
0.bit_length.should == 0
1.bit_length.should == 1
0xff.bit_length.should == 8
0x100.bit_length.should == 9
(2**12 - 1).bit_length.should == 12
(2**12).bit_length.should == 13
(2**12 + 1).bit_length.should == 13
end
it "returns the position of the leftmost 0 bit of a negative number" do
-1.bit_length.should == 0
-2.bit_length.should == 1
-3.bit_length.should == 2
-4.bit_length.should == 2
-5.bit_length.should == 3
n = fixnum_min.bit_length
fixnum_min[n].should == 1
fixnum_min[n - 1].should == 0
(-2**12 - 1).bit_length.should == 13
(-2**12).bit_length.should == 12
(-2**12 + 1).bit_length.should == 12
-0x101.bit_length.should == 9
-0x100.bit_length.should == 8
-0xff.bit_length.should == 8
-2.bit_length.should == 1
-1.bit_length.should == 0
end
end
context "bignum" do
it "returns the position of the leftmost bit of a positive number" do
(2**1000-1).bit_length.should == 1000
(2**1000).bit_length.should == 1001
(2**1000+1).bit_length.should == 1001
(2**10000-1).bit_length.should == 10000
(2**10000).bit_length.should == 10001
(2**10000+1).bit_length.should == 10001
(1 << 100).bit_length.should == 101
(1 << 100).succ.bit_length.should == 101
(1 << 100).pred.bit_length.should == 100
(1 << 10000).bit_length.should == 10001
end
it "returns the position of the leftmost 0 bit of a negative number" do
(-2**10000-1).bit_length.should == 10001
(-2**10000).bit_length.should == 10000
(-2**10000+1).bit_length.should == 10000
(-2**1000-1).bit_length.should == 1001
(-2**1000).bit_length.should == 1000
(-2**1000+1).bit_length.should == 1000
((-1 << 100)-1).bit_length.should == 101
((-1 << 100)-1).succ.bit_length.should == 100
((-1 << 100)-1).pred.bit_length.should == 101
((-1 << 10000)-1).bit_length.should == 10001
end
end
end
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