Re: [PATCH 3/6] C-language equivalents of include/asm-*/bitops.h
From: Richard Henderson <hidden>
Date: 2006-01-26 00:08:21
Also in:
linuxppc-dev, lkml, sparclinux
On Wed, Jan 25, 2006 at 08:02:50PM +0000, Russell King wrote:
quoted
+ 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. r~