5cde7656d0
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>
72 lines
2 KiB
C
72 lines
2 KiB
C
/*
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* There are multiple 16-bit CRC polynomials in common use, but this is
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* *the* standard CRC-32 polynomial, first popularized by Ethernet.
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* x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x^1+x^0
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*/
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#define CRCPOLY_LE 0xedb88320
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#define CRCPOLY_BE 0x04c11db7
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/*
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* This is the CRC32c polynomial, as outlined by Castagnoli.
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* x^32+x^28+x^27+x^26+x^25+x^23+x^22+x^20+x^19+x^18+x^14+x^13+x^11+x^10+x^9+
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* x^8+x^6+x^0
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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.
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* For larger systems choose same as CPU architecture as default.
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* This works well on X86_64, SPARC64 systems. This may require some
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* elaboration after experiments with other architectures.
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*/
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#ifndef CRC_LE_BITS
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# ifdef CONFIG_64BIT
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# define CRC_LE_BITS 64
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# else
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# define CRC_LE_BITS 32
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# endif
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#endif
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#ifndef CRC_BE_BITS
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# ifdef CONFIG_64BIT
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# define CRC_BE_BITS 64
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# else
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# define CRC_BE_BITS 32
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# endif
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#endif
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/*
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* Little-endian CRC computation. Used with serial bit streams sent
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* lsbit-first. Be sure to use cpu_to_le32() to append the computed CRC.
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*/
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#if CRC_LE_BITS > 64 || CRC_LE_BITS < 1 || CRC_LE_BITS == 16 || \
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CRC_LE_BITS & CRC_LE_BITS-1
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# error "CRC_LE_BITS must be one of {1, 2, 4, 8, 32, 64}"
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#endif
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/*
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* Big-endian CRC computation. Used with serial bit streams sent
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* msbit-first. Be sure to use cpu_to_be32() to append the computed CRC.
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*/
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#if CRC_BE_BITS > 64 || CRC_BE_BITS < 1 || CRC_BE_BITS == 16 || \
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CRC_BE_BITS & CRC_BE_BITS-1
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# error "CRC_BE_BITS must be one of {1, 2, 4, 8, 32, 64}"
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#endif
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