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Message-ID: <20210301192646.GA2766@voyager>
Date: Mon, 1 Mar 2021 20:26:46 +0100
From: Markus Wichmann <nullplan@....net>
To: musl@...ts.openwall.com
Subject: Re: [PATCH v2 2/2] Use modulo instead of mul+sub in
__secs_to_tm
On Sun, Feb 28, 2021 at 07:58:27PM +0000, Jon Chesterfield wrote:
> Note that module coming for free with division doesn't make it cheap.
> Integer division is far more expensive that integer multiply on ~ every
> architecture. Several architectures implement division in software. It's
> not cheap on x86, despite the dedicated instruction.
>
> Cheers
And then there's PowerPC, which does have a divide instruction but no
modulo. The manual explicitly states that if you need a modulo, you are
supposed to divide, multiply, and subtract.
Ciao,
Markus
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