| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | /* How many bits at a time to use. Requires a table of 4<<CRC_xx_BITS bytes. */ |
| 10 | /* For less performance-sensitive, use 4 */ |
| 11 | #ifndef CRC_LE_BITS |
| 12 | # define CRC_LE_BITS 8 |
| 13 | #endif |
| 14 | #ifndef CRC_BE_BITS |
| 15 | # define CRC_BE_BITS 8 |
| 16 | #endif |
| 17 | |
| 18 | /* |
| 19 | * Little-endian CRC computation. Used with serial bit streams sent |
| 20 | * lsbit-first. Be sure to use cpu_to_le32() to append the computed CRC. |
| 21 | */ |
| 22 | #if CRC_LE_BITS > 8 || CRC_LE_BITS < 1 || CRC_LE_BITS & CRC_LE_BITS-1 |
| 23 | # error CRC_LE_BITS must be a power of 2 between 1 and 8 |
| 24 | #endif |
| 25 | |
| 26 | /* |
| 27 | * Big-endian CRC computation. Used with serial bit streams sent |
| 28 | * msbit-first. Be sure to use cpu_to_be32() to append the computed CRC. |
| 29 | */ |
| 30 | #if CRC_BE_BITS > 8 || CRC_BE_BITS < 1 || CRC_BE_BITS & CRC_BE_BITS-1 |
| 31 | # error CRC_BE_BITS must be a power of 2 between 1 and 8 |
| 32 | #endif |