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Permission is hereby granted, free of charge, to any person obtaining a copy 
of this software and associated documentation files (the "Software"), to deal 
in the Software without restriction, including without limitation the rights 
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
copies of the Software, and to permit persons to whom the Software is 
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in 
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 
THE SOFTWARE.
reempt-rt/x86'>v5.14/standard/preempt-rt/x86 Yocto Linux Embedded kernelGrokmirror user
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path: root/lib/crc8.c
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/*
 * 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");