lib/crc32defs.h

   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