Multiply with negative integer just by shifting.
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Published on 2010-05-01T21:21:59Z
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2010/05/01
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Hi,
I'm trying to find a way to multiply an integer value with negative value just with bit shifting.
Usually I do this by shifting with the power of 2 which is closest to my factor and just adding / subtracting the rest, e.g. x * 7 = ((x << 3) - x)
Let's say I'd want to calculate x * -112. The only way I can imagine is -((x << 7) - (x << 4), so to calculate x * 112 and negate it afterwards.
Is there a "prettier" way to do this?
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