/* * Copyright (c) 2011 Broadcom Corporation * * Permission to use, copy, modify, and/or distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include /* * crc8_populate_msb - fill crc table for given polynomial in reverse bit order. * * table: table to be filled. * polynomial: polynomial for which table is to be filled. */ void crc8_populate_msb(u8 table[CRC8_TABLE_SIZE], u8 polynomial) { int i, j; const u8 msbit = 0x80; u8 t = msbit; table[0] = 0; for (i = 1; i < CRC8_TABLE_SIZE; i *= 2) { t = (t << 1) ^ (t & msbit ? polynomial : 0); for (j = 0; j < i; j++) table[i+j] = table[j] ^ t; } } EXPORT_SYMBOL(crc8_populate_msb); /* * crc8_populate_lsb - fill crc table for given polynomial in regular bit order. * * table: table to be filled. * polynomial: polynomial for which table is to be filled. */ void crc8_populate_lsb(u8 table[CRC8_TABLE_SIZE], u8 polynomial) { int i, j; u8 t = 1; table[0] = 0; for (i = (CRC8_TABLE_SIZE >> 1); i; i >>= 1) { t = (t >> 1) ^ (t & 1 ? polynomial : 0); for (j = 0; j < CRC8_TABLE_SIZE; j += 2*i) table[i+j] = table[j] ^ t; } } EXPORT_SYMBOL(crc8_populate_lsb); /* * crc8 - calculate a crc8 over the given input data. * * table: crc table used for calculation. * pdata: pointer to data buffer. * nbytes: number of bytes in data buffer. * crc: previous returned crc8 value. */ u8 crc8(const u8 table[CRC8_TABLE_SIZE], u8 *pdata, size_t nbytes, u8 crc) { /* loop over the buffer data */ while (nbytes-- > 0) crc = table[(crc ^ *pdata++) & 0xff]; return crc; } EXPORT_SYMBOL(crc8); MODULE_DESCRIPTION("CRC8 (by Williams, Ross N.) function"); MODULE_AUTHOR("Broadcom Corporation"); MODULE_LICENSE("Dual BSD/GPL"); ption>
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