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