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From: | "Andrew Crabtree" <andrewc AT rosemail DOT rose DOT hp DOT com> |
Newsgroups: | comp.os.msdos.djgpp |
Subject: | Re: DJGPP division optimisations |
Date: | Mon, 13 Jul 1998 16:17:42 -0700 |
Organization: | Hewlett-Packard, Roseville |
Lines: | 13 |
Message-ID: | <6oe4in$1m7$1@rosenews.rose.hp.com> |
References: | <35AA8994 DOT 3FC1 AT virgin DOT net> |
NNTP-Posting-Host: | ros51675cra.rose.hp.com |
To: | djgpp AT delorie DOT com |
DJ-Gateway: | from newsgroup comp.os.msdos.djgpp |
>on long integers. In the source code I used x /= 2; y /=2; for clarity, >on the assumption that the compiler would replace these operations with >shifts.However, it seems this isn't a valid assumption. Replacing the code with >x >>= 1; y >>= 1; made a large speed up. Just a guess, but maybe GCC only does that optimization on unisignd integers, not signed integers. Andy
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