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bitWidth is wrong for -(power-of-two) #115

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wadetregaskis opened this issue Oct 9, 2023 · 0 comments
Open

bitWidth is wrong for -(power-of-two) #115

wadetregaskis opened this issue Oct 9, 2023 · 0 comments

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@wadetregaskis
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wadetregaskis commented Oct 9, 2023 •
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XCTAssertEqual(64, BigInt(Int64.min).bitWidth)

That fails, because bitWidth returns 65. It's not correctly handling the cases of 0b1 followed by some number of 0b0's, because with two's complement the magnitude of your minimum value is one higher than of your maximum value. Doing magnitude.bitWidth + 1 fails to account for this.
@wadetregaskis wadetregaskis changed the title bitWidth is wrong for -(power-of-two-plus-one) bitWidth is wrong for -(power-of-two) Oct 9, 2023
@wadetregaskis wadetregaskis mentioned this issue Oct 10, 2023
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