crc32.h revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2002 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#ifndef _SYS_CRC32_H
#define _SYS_CRC32_H
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* CRC32, the 32-bit Cyclic Redundancy Check, is a well-known way to
* generate checksums or hashes. Extensive literature on the theory
* behind CRC is available on the web; we won't recapitulate it here.
* We must, however, cover a few basics to explain the services we're
* providing.
*
* A CRC function is defined by two parameters: an initial value and a
* 32-bit integer that encodes its generating polynomial (explained later).
* Given these values, the CRC of any bitstream is defined as follows:
*
* crc = CRC32_INITIAL;
* foreach (bit of data)
* if (bit == (crc & 1))
* crc = (crc >> 1);
* else
* crc = (crc >> 1) ^ CRC32_POLY;
*
* That's it. The algorithm is both simple and surprisingly powerful:
* CRC32 has been proven to detect all single-bit errors, all double-bit
* errors, and all burst errors up to 32 bits long.
*
* The most common values for the CRC parameters are:
*
* CRC32_INITIAL: 0 or -1
* CRC32_POLY 0xEDB88320
*
* There is no particular constraint on the initial value; any will yield a
* valid CRC. (OK, then why not always use zero? Because CRC was originally
* designed for serial transmission, in which one common form of error
* was a burst of zeroes. Note that if crc == 0, and we fold in a zero bit,
* we still have crc == 0. Therefore, if the CRC's initial value is zero,
* an arbitrarily long run of zeroes can be prepended to a packet without
* being detected.)
*
* The constraint on the polynomial is that it must be of degree 32
* and must be primitive in the Galois field of polynomials modulo 2.
* Any such polynomial will yield a valid CRC. There's no particular
* advantage to one such polynomial over another, so the world has
* largely standardized on a particular one, 0xEDB88320. [The nth bit
* of this integer is the coefficient of x^n; the coefficient of x^32
* is implicitly 1.]
*
* Of course, we rarely process data bitwise in software. When processing
* data bytewise, the following calculation is equivalent to the bitwise one:
*
* crc = CRC32_INITIAL;
* foreach (byte of data)
* for (crc ^= byte, i = 8; i > 0; i--)
* crc = (crc >> 1) ^ (-(crc & 1) & CRC32_POLY);
*
* Note that we still have a bitwise loop in there. We can avoid this
* by precomputing the CRC of each possible byte [i.e. 0-255] using the
* algorithm above and storing the results in a lookup table. Given
* such a table, the CRC can be computed quite efficiently as follows:
*
* crc = CRC32_INITIAL;
* foreach (byte of data)
* crc = (crc >> 8) ^ crc32_table[(crc ^ byte) & 0xFF];
*
* The macros below support this form of CRC computation.
*
* We also define a pre-computed crc32_table[] for the polynomial 0xEDB88320.
* This is the only CRC polynomial we actually use in Solaris.
*/
#ifdef __cplusplus
extern "C" {
#endif
/*
* Initialize a CRC table [256 uint32_t's] with the given polynomial.
*/
{ \
}
/*
* Compute a 32-bit CRC using the specified starting value and table.
* Typical usage: CRC32(crc, buf, size, -1U, crc32_table).
*/
{ \
}
/*
* As above, but operate on a null-terminated string instead of an
* array of known size. Computes both the crc and the string length.
* Typical usage: CRC32_STRING(crc, len, str, -1U, crc32_table).
*/
{ \
}
/*
* The polynomial we generally use in Solaris.
*/
#define CRC32_POLY 0xEDB88320U
/*
* The pre-computed table values for CRC32_POLY.
*/
#define CRC32_TABLE \
0x00000000U, 0x77073096U, 0xEE0E612CU, 0x990951BAU, \
0x076DC419U, 0x706AF48FU, 0xE963A535U, 0x9E6495A3U, \
0x0EDB8832U, 0x79DCB8A4U, 0xE0D5E91EU, 0x97D2D988U, \
0x09B64C2BU, 0x7EB17CBDU, 0xE7B82D07U, 0x90BF1D91U, \
0x1DB71064U, 0x6AB020F2U, 0xF3B97148U, 0x84BE41DEU, \
0x1ADAD47DU, 0x6DDDE4EBU, 0xF4D4B551U, 0x83D385C7U, \
0x136C9856U, 0x646BA8C0U, 0xFD62F97AU, 0x8A65C9ECU, \
0x14015C4FU, 0x63066CD9U, 0xFA0F3D63U, 0x8D080DF5U, \
0x3B6E20C8U, 0x4C69105EU, 0xD56041E4U, 0xA2677172U, \
0x3C03E4D1U, 0x4B04D447U, 0xD20D85FDU, 0xA50AB56BU, \
0x35B5A8FAU, 0x42B2986CU, 0xDBBBC9D6U, 0xACBCF940U, \
0x32D86CE3U, 0x45DF5C75U, 0xDCD60DCFU, 0xABD13D59U, \
0x26D930ACU, 0x51DE003AU, 0xC8D75180U, 0xBFD06116U, \
0x21B4F4B5U, 0x56B3C423U, 0xCFBA9599U, 0xB8BDA50FU, \
0x2802B89EU, 0x5F058808U, 0xC60CD9B2U, 0xB10BE924U, \
0x2F6F7C87U, 0x58684C11U, 0xC1611DABU, 0xB6662D3DU, \
0x76DC4190U, 0x01DB7106U, 0x98D220BCU, 0xEFD5102AU, \
0x71B18589U, 0x06B6B51FU, 0x9FBFE4A5U, 0xE8B8D433U, \
0x7807C9A2U, 0x0F00F934U, 0x9609A88EU, 0xE10E9818U, \
0x7F6A0DBBU, 0x086D3D2DU, 0x91646C97U, 0xE6635C01U, \
0x6B6B51F4U, 0x1C6C6162U, 0x856530D8U, 0xF262004EU, \
0x6C0695EDU, 0x1B01A57BU, 0x8208F4C1U, 0xF50FC457U, \
0x65B0D9C6U, 0x12B7E950U, 0x8BBEB8EAU, 0xFCB9887CU, \
0x62DD1DDFU, 0x15DA2D49U, 0x8CD37CF3U, 0xFBD44C65U, \
0x4DB26158U, 0x3AB551CEU, 0xA3BC0074U, 0xD4BB30E2U, \
0x4ADFA541U, 0x3DD895D7U, 0xA4D1C46DU, 0xD3D6F4FBU, \
0x4369E96AU, 0x346ED9FCU, 0xAD678846U, 0xDA60B8D0U, \
0x44042D73U, 0x33031DE5U, 0xAA0A4C5FU, 0xDD0D7CC9U, \
0x5005713CU, 0x270241AAU, 0xBE0B1010U, 0xC90C2086U, \
0x5768B525U, 0x206F85B3U, 0xB966D409U, 0xCE61E49FU, \
0x5EDEF90EU, 0x29D9C998U, 0xB0D09822U, 0xC7D7A8B4U, \
0x59B33D17U, 0x2EB40D81U, 0xB7BD5C3BU, 0xC0BA6CADU, \
0xEDB88320U, 0x9ABFB3B6U, 0x03B6E20CU, 0x74B1D29AU, \
0xEAD54739U, 0x9DD277AFU, 0x04DB2615U, 0x73DC1683U, \
0xE3630B12U, 0x94643B84U, 0x0D6D6A3EU, 0x7A6A5AA8U, \
0xE40ECF0BU, 0x9309FF9DU, 0x0A00AE27U, 0x7D079EB1U, \
0xF00F9344U, 0x8708A3D2U, 0x1E01F268U, 0x6906C2FEU, \
0xF762575DU, 0x806567CBU, 0x196C3671U, 0x6E6B06E7U, \
0xFED41B76U, 0x89D32BE0U, 0x10DA7A5AU, 0x67DD4ACCU, \
0xF9B9DF6FU, 0x8EBEEFF9U, 0x17B7BE43U, 0x60B08ED5U, \
0xD6D6A3E8U, 0xA1D1937EU, 0x38D8C2C4U, 0x4FDFF252U, \
0xD1BB67F1U, 0xA6BC5767U, 0x3FB506DDU, 0x48B2364BU, \
0xD80D2BDAU, 0xAF0A1B4CU, 0x36034AF6U, 0x41047A60U, \
0xDF60EFC3U, 0xA867DF55U, 0x316E8EEFU, 0x4669BE79U, \
0xCB61B38CU, 0xBC66831AU, 0x256FD2A0U, 0x5268E236U, \
0xCC0C7795U, 0xBB0B4703U, 0x220216B9U, 0x5505262FU, \
0xC5BA3BBEU, 0xB2BD0B28U, 0x2BB45A92U, 0x5CB36A04U, \
0xC2D7FFA7U, 0xB5D0CF31U, 0x2CD99E8BU, 0x5BDEAE1DU, \
0x9B64C2B0U, 0xEC63F226U, 0x756AA39CU, 0x026D930AU, \
0x9C0906A9U, 0xEB0E363FU, 0x72076785U, 0x05005713U, \
0x95BF4A82U, 0xE2B87A14U, 0x7BB12BAEU, 0x0CB61B38U, \
0x92D28E9BU, 0xE5D5BE0DU, 0x7CDCEFB7U, 0x0BDBDF21U, \
0x86D3D2D4U, 0xF1D4E242U, 0x68DDB3F8U, 0x1FDA836EU, \
0x81BE16CDU, 0xF6B9265BU, 0x6FB077E1U, 0x18B74777U, \
0x88085AE6U, 0xFF0F6A70U, 0x66063BCAU, 0x11010B5CU, \
0x8F659EFFU, 0xF862AE69U, 0x616BFFD3U, 0x166CCF45U, \
0xA00AE278U, 0xD70DD2EEU, 0x4E048354U, 0x3903B3C2U, \
0xA7672661U, 0xD06016F7U, 0x4969474DU, 0x3E6E77DBU, \
0xAED16A4AU, 0xD9D65ADCU, 0x40DF0B66U, 0x37D83BF0U, \
0xA9BCAE53U, 0xDEBB9EC5U, 0x47B2CF7FU, 0x30B5FFE9U, \
0xBDBDF21CU, 0xCABAC28AU, 0x53B39330U, 0x24B4A3A6U, \
0xBAD03605U, 0xCDD70693U, 0x54DE5729U, 0x23D967BFU, \
0xB3667A2EU, 0xC4614AB8U, 0x5D681B02U, 0x2A6F2B94U, \
0xB40BBE37U, 0xC30C8EA1U, 0x5A05DF1BU, 0x2D02EF8DU
#ifdef _KERNEL
/*
* The kernel's pre-computed table for CRC32_POLY.
*/
#endif /* _KERNEL */
#ifdef __cplusplus
}
#endif
#endif /* _SYS_CRC32_H */