LXR linux/lib/crc32defs.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 * There are multiple 16-bit CRC polynomials in common use, but this is
   4 * *the* standard CRC-32 polynomial, first popularized by Ethernet.
   5 * 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
   6 */
   7#define CRCPOLY_LE 0xedb88320
   8#define CRCPOLY_BE 0x04c11db7
   9
  10/*
  11 * This is the CRC32c polynomial, as outlined by Castagnoli.
  12 * 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+
  13 * x^8+x^6+x^0
  14 */
  15#define CRC32C_POLY_LE 0x82F63B78
  16
  17/* Try to choose an implementation variant via Kconfig */
  18#ifdef CONFIG_CRC32_SLICEBY8
  19# define CRC_LE_BITS 64
  20# define CRC_BE_BITS 64
  21#endif
  22#ifdef CONFIG_CRC32_SLICEBY4
  23# define CRC_LE_BITS 32
  24# define CRC_BE_BITS 32
  25#endif
  26#ifdef CONFIG_CRC32_SARWATE
  27# define CRC_LE_BITS 8
  28# define CRC_BE_BITS 8
  29#endif
  30#ifdef CONFIG_CRC32_BIT
  31# define CRC_LE_BITS 1
  32# define CRC_BE_BITS 1
  33#endif
  34
  35/*
  36 * How many bits at a time to use.  Valid values are 1, 2, 4, 8, 32 and 64.
  37 * For less performance-sensitive, use 4 or 8 to save table size.
  38 * For larger systems choose same as CPU architecture as default.
  39 * This works well on X86_64, SPARC64 systems. This may require some
  40 * elaboration after experiments with other architectures.
  41 */
  42#ifndef CRC_LE_BITS
  43#  ifdef CONFIG_64BIT
  44#  define CRC_LE_BITS 64
  45#  else
  46#  define CRC_LE_BITS 32
  47#  endif
  48#endif
  49#ifndef CRC_BE_BITS
  50#  ifdef CONFIG_64BIT
  51#  define CRC_BE_BITS 64
  52#  else
  53#  define CRC_BE_BITS 32
  54#  endif
  55#endif
  56
  57/*
  58 * Little-endian CRC computation.  Used with serial bit streams sent
  59 * lsbit-first.  Be sure to use cpu_to_le32() to append the computed CRC.
  60 */
  61#if CRC_LE_BITS > 64 || CRC_LE_BITS < 1 || CRC_LE_BITS == 16 || \
  62        CRC_LE_BITS & CRC_LE_BITS-1
  63# error "CRC_LE_BITS must be one of {1, 2, 4, 8, 32, 64}"
  64#endif
  65
  66/*
  67 * Big-endian CRC computation.  Used with serial bit streams sent
  68 * msbit-first.  Be sure to use cpu_to_be32() to append the computed CRC.
  69 */
  70#if CRC_BE_BITS > 64 || CRC_BE_BITS < 1 || CRC_BE_BITS == 16 || \
  71        CRC_BE_BITS & CRC_BE_BITS-1
  72# error "CRC_BE_BITS must be one of {1, 2, 4, 8, 32, 64}"
  73#endif
  74