tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
crc32: select an algorithm via Kconfig
Allow the kernel builder to choose a crc32* algorithm for the kernel.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Cc: Bob Pearson <rpearson@systemfabricworks.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
authored by
Darrick J. Wong
and committed by
Linus Torvalds
5cde7656
577eba9e
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+43
lib/Kconfig
+43
lib/Kconfig
···
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and crc32_be over byte strings with random alignment and length
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and computes the total elapsed time and number of bytes processed.
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choice
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prompt "CRC32 implementation"
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depends on CRC32
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default CRC32_SLICEBY8
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config CRC32_SLICEBY8
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bool "Slice by 8 bytes"
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help
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Calculate checksum 8 bytes at a time with a clever slicing algorithm.
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This is the fastest algorithm, but comes with a 8KiB lookup table.
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Most modern processors have enough cache to hold this table without
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thrashing the cache.
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This is the default implementation choice. Choose this one unless
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you have a good reason not to.
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config CRC32_SLICEBY4
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bool "Slice by 4 bytes"
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help
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Calculate checksum 4 bytes at a time with a clever slicing algorithm.
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This is a bit slower than slice by 8, but has a smaller 4KiB lookup
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table.
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Only choose this option if you know what you are doing.
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config CRC32_SARWATE
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bool "Sarwate's Algorithm (one byte at a time)"
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help
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Calculate checksum a byte at a time using Sarwate's algorithm. This
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is not particularly fast, but has a small 256 byte lookup table.
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Only choose this option if you know what you are doing.
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config CRC32_BIT
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bool "Classic Algorithm (one bit at a time)"
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help
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Calculate checksum one bit at a time. This is VERY slow, but has
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no lookup table. This is provided as a debugging option.
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Only choose this option if you are debugging crc32.
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endchoice
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config CRC7
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tristate "CRC7 functions"
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help
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lib/crc32defs.h
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lib/crc32defs.h
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*/
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#define CRC32C_POLY_LE 0x82F63B78
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/* Try to choose an implementation variant via Kconfig */
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#ifdef CONFIG_CRC32_SLICEBY8
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# define CRC_LE_BITS 64
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# define CRC_BE_BITS 64
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#endif
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#ifdef CONFIG_CRC32_SLICEBY4
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# define CRC_LE_BITS 32
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# define CRC_BE_BITS 32
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#endif
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#ifdef CONFIG_CRC32_SARWATE
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# define CRC_LE_BITS 8
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# define CRC_BE_BITS 8
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#endif
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#ifdef CONFIG_CRC32_BIT
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# define CRC_LE_BITS 1
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# define CRC_BE_BITS 1
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#endif
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/*
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* How many bits at a time to use. Valid values are 1, 2, 4, 8, 32 and 64.
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* For less performance-sensitive, use 4 or 8 to save table size.