linux/lib/crc32defs.h
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   1/*
   2 * There are multiple 16-bit CRC polynomials in common use, but this is
   3 * *the* standard CRC-32 polynomial, first popularized by Ethernet.
   4 * 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
   5 */
   6#define CRCPOLY_LE 0xedb88320
   7#define CRCPOLY_BE 0x04c11db7
   8
   9/*
  10 * This is the CRC32c polynomial, as outlined by Castagnoli.
  11 * 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+
  12 * x^8+x^6+x^0
  13 */
  14#define CRC32C_POLY_LE 0x82F63B78
  15
  16/* Try to choose an implementation variant via Kconfig */
  17#ifdef CONFIG_CRC32_SLICEBY8
  18# define CRC_LE_BITS 64
  19# define CRC_BE_BITS 64
  20#endif
  21#ifdef CONFIG_CRC32_SLICEBY4
  22# define CRC_LE_BITS 32
  23# define CRC_BE_BITS 32
  24#endif
  25#ifdef CONFIG_CRC32_SARWATE
  26# define CRC_LE_BITS 8
  27# define CRC_BE_BITS 8
  28#endif
  29#ifdef CONFIG_CRC32_BIT
  30# define CRC_LE_BITS 1
  31# define CRC_BE_BITS 1
  32#endif
  33
  34/*
  35 * How many bits at a time to use.  Valid values are 1, 2, 4, 8, 32 and 64.
  36 * For less performance-sensitive, use 4 or 8 to save table size.
  37 * For larger systems choose same as CPU architecture as default.
  38 * This works well on X86_64, SPARC64 systems. This may require some
  39 * elaboration after experiments with other architectures.
  40 */
  41#ifndef CRC_LE_BITS
  42#  ifdef CONFIG_64BIT
  43#  define CRC_LE_BITS 64
  44#  else
  45#  define CRC_LE_BITS 32
  46#  endif
  47#endif
  48#ifndef CRC_BE_BITS
  49#  ifdef CONFIG_64BIT
  50#  define CRC_BE_BITS 64
  51#  else
  52#  define CRC_BE_BITS 32
  53#  endif
  54#endif
  55
  56/*
  57 * Little-endian CRC computation.  Used with serial bit streams sent
  58 * lsbit-first.  Be sure to use cpu_to_le32() to append the computed CRC.
  59 */
  60#if CRC_LE_BITS > 64 || CRC_LE_BITS < 1 || CRC_LE_BITS == 16 || \
  61        CRC_LE_BITS & CRC_LE_BITS-1
  62# error "CRC_LE_BITS must be one of {1, 2, 4, 8, 32, 64}"
  63#endif
  64
  65/*
  66 * Big-endian CRC computation.  Used with serial bit streams sent
  67 * msbit-first.  Be sure to use cpu_to_be32() to append the computed CRC.
  68 */
  69#if CRC_BE_BITS > 64 || CRC_BE_BITS < 1 || CRC_BE_BITS == 16 || \
  70        CRC_BE_BITS & CRC_BE_BITS-1
  71# error "CRC_BE_BITS must be one of {1, 2, 4, 8, 32, 64}"
  72#endif
  73
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