Re: Signed multiplication

From: Rhialto <>
Date: Thu, 5 Nov 2009 23:12:06 +0100
Message-ID: <>
On Thu 05 Nov 2009 at 19:11:18 +0100, Ullrich von Bassewitz wrote:
> (the result should be $FFFFFFFC instead of $1FFFC). Currently, I'm using an
> unsigned 16x16=>32 multiplication with the absolute values of the operands,
> and adjust the sign of the result. The question is, if there is a faster
> method than this.

I don't think so, at least I've never seen one. Even on CPUs that have
MUltiply intructions in signed and unsigned variants, where you can do
several narrow MULs to make a wider  one, I don't think I've ever seen
anything other than unsigned multiplications used.

>         Uz
___ Olaf 'Rhialto' Seibert    -- You author it, and I'll reader it.
\X/ rhialto/at/      -- Cetero censeo "authored" delendum esse.

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Received on 2009-11-05 23:00:03

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