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