| 1 | |
| 2 | * Copyright (c) 2011 Broadcom Corporation
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| 3 | *
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| 4 | * Permission to use, copy, modify, and/or distribute this software for any
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| 5 | * purpose with or without fee is hereby granted, provided that the above
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| 6 | * copyright notice and this permission notice appear in all copies.
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| 7 | *
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| 8 | * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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| 9 | * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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| 10 | * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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| 11 | * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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| 12 | * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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| 13 | * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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| 14 | * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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| 15 |
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| 16 |
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| 17 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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| 18 |
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| 19 | #include <linux/crc8.h>
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| 20 | #include <linux/export.h>
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| 21 | #include <linux/module.h>
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| 22 | #include <linux/printk.h>
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| 23 |
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| 24 | |
| 25 | * crc8_populate_msb - fill crc table for given polynomial in reverse bit order.
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| 26 | *
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| 27 | * @table: table to be filled.
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| 28 | * @polynomial: polynomial for which table is to be filled.
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| 29 |
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| 30 | void crc8_populate_msb(u8 table[CRC8_TABLE_SIZE], u8 polynomial)
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| 31 | {
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| 32 | int i, j;
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| 33 | const u8 msbit = 0x80;
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| 34 | u8 t = msbit;
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| 35 |
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| 36 | table[0] = 0;
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| 37 |
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| 38 | for (i = 1; i < CRC8_TABLE_SIZE; i *= 2) {
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| 39 | t = (t << 1) ^ (t & msbit ? polynomial : 0);
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| 40 | for (j = 0; j < i; j++)
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| 41 | table[i+j] = table[j] ^ t;
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| 42 | }
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| 43 | }
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| 44 | EXPORT_SYMBOL(crc8_populate_msb);
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| 45 |
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| 46 | |
| 47 | * crc8_populate_lsb - fill crc table for given polynomial in regular bit order.
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| 48 | *
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| 49 | * @table: table to be filled.
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| 50 | * @polynomial: polynomial for which table is to be filled.
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| 51 |
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| 52 | void crc8_populate_lsb(u8 table[CRC8_TABLE_SIZE], u8 polynomial)
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| 53 | {
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| 54 | int i, j;
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| 55 | u8 t = 1;
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| 56 |
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| 57 | table[0] = 0;
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| 58 |
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| 59 | for (i = (CRC8_TABLE_SIZE >> 1); i; i >>= 1) {
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| 60 | t = (t >> 1) ^ (t & 1 ? polynomial : 0);
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| 61 | for (j = 0; j < CRC8_TABLE_SIZE; j += 2*i)
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| 62 | table[i+j] = table[j] ^ t;
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| 63 | }
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| 64 | }
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| 65 | EXPORT_SYMBOL(crc8_populate_lsb);
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| 66 |
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| 67 | |
| 68 | * crc8 - calculate a crc8 over the given input data.
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| 69 | *
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| 70 | * @table: crc table used for calculation.
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| 71 | * @pdata: pointer to data buffer.
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| 72 | * @nbytes: number of bytes in data buffer.
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| 73 | * @crc: previous returned crc8 value.
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| 74 |
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| 75 | u8 crc8(const u8 table[CRC8_TABLE_SIZE], const u8 *pdata, size_t nbytes, u8 crc)
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| 76 | {
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| 77 |
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| 78 | while (nbytes-- > 0)
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| 79 | crc = table[(crc ^ *pdata++) & 0xff];
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| 80 |
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| 81 | return crc;
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| 82 | }
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| 83 | EXPORT_SYMBOL(crc8);
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| 84 |
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| 85 | MODULE_DESCRIPTION("CRC8 (by Williams, Ross N.) function");
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| 86 | MODULE_AUTHOR("Broadcom Corporation");
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| 87 | MODULE_LICENSE("Dual BSD/GPL");
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