Date: Wed, 27 Apr 2005 22:26:45 +0000 (UTC) From: Marcel Moolenaar <marcel@FreeBSD.org> To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/libkern crc32.c src/sys/sys systm.h Message-ID: <200504272226.j3RMQjNe068620@repoman.freebsd.org>
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marcel 2005-04-27 22:26:45 UTC
FreeBSD src repository
Modified files:
sys/libkern crc32.c
sys/sys systm.h
Log:
Refactor the CRC-32 code to enhance its usability. Move the actual
CRC logic to a new function: crc32_raw() that obtains the initial
CRC value as well as leaves any post-processing to the caller. As
such, it can be used when the initial CRC value is not ~0U or when
the final CRC value does need to be inverted (bitwise). It also
means that crc32_raw() can be called repeatedly when the data is
not available as a single block, such as for scatter/gather lists
and the likes.
Avoid the additional call overhead incured by the refactoring by
moving the implementation off crc32() to sys/systm.h and making it
inlinable. Since crc32_raw() is itself trivial and since it may
be used in loops that iterate over fragments, having it available
for inlining can be beneficial. Hence, move its implementation
to sys/systm.h as well.
Keep the original implementation of crc32() in libkern/crc32.c for
documentation purposes (as a comment of course).
Triggered by: Jose M Rodriguez (josemi at freebsd dot jazztel dot es)
Discussed on: current@
Tested on: amd64, ia64 (BVO having GPT partitions)
Jargon file candidate: BVO = By Virtue Of :-)
Revision Changes Path
1.4 +18 -15 src/sys/libkern/crc32.c
1.233 +21 -1 src/sys/sys/systm.h
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