Messages in this thread | | | Date | Wed, 25 Jan 2006 16:06:18 -0800 | From | Richard Henderson <> | Subject | Re: [PATCH 3/6] C-language equivalents of include/asm-*/bitops.h |
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On Wed, Jan 25, 2006 at 08:02:50PM +0000, Russell King wrote: > > + s = 16; if (word << 16 != 0) s = 0; b += s; word >>= s; > > + s = 8; if (word << 24 != 0) s = 0; b += s; word >>= s; > > + s = 4; if (word << 28 != 0) s = 0; b += s; word >>= s; ... > Basically, shifts which depend on a variable are more expensive than > constant-based shifts.
Actually, they're all constant shifts. Just written stupidly.
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