/*
   * 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 <linux/module.h>
  #include <linux/crc8.h>
  #include <linux/printk.h>
  
  /*
   * 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");