xref: /OK3568_Linux_fs/u-boot/lib/crc8.c (revision 4882a59341e53eb6f0b4789bf948001014eff981) 
1*4882a593Smuzhiyun /*
2*4882a593Smuzhiyun  * Copyright (c) 2013 Google, Inc
3*4882a593Smuzhiyun  *
4*4882a593Smuzhiyun  * SPDX-License-Identifier:	GPL-2.0+
5*4882a593Smuzhiyun  */
6*4882a593Smuzhiyun 
7*4882a593Smuzhiyun #include "linux/crc8.h"
8*4882a593Smuzhiyun 
9*4882a593Smuzhiyun #define POLY	(0x1070U << 3)
10*4882a593Smuzhiyun 
_crc8(unsigned short data)11*4882a593Smuzhiyun static unsigned char _crc8(unsigned short data)
12*4882a593Smuzhiyun {
13*4882a593Smuzhiyun 	int i;
14*4882a593Smuzhiyun 
15*4882a593Smuzhiyun 	for (i = 0; i < 8; i++) {
16*4882a593Smuzhiyun 		if (data & 0x8000)
17*4882a593Smuzhiyun 			data = data ^ POLY;
18*4882a593Smuzhiyun 		data = data << 1;
19*4882a593Smuzhiyun 	}
20*4882a593Smuzhiyun 
21*4882a593Smuzhiyun 	return (unsigned char)(data >> 8);
22*4882a593Smuzhiyun }
23*4882a593Smuzhiyun 
crc8(unsigned int crc,const unsigned char * vptr,int len)24*4882a593Smuzhiyun unsigned int crc8(unsigned int crc, const unsigned char *vptr, int len)
25*4882a593Smuzhiyun {
26*4882a593Smuzhiyun 	int i;
27*4882a593Smuzhiyun 
28*4882a593Smuzhiyun 	for (i = 0; i < len; i++)
29*4882a593Smuzhiyun 		crc = _crc8((crc ^ vptr[i]) << 8);
30*4882a593Smuzhiyun 
31*4882a593Smuzhiyun 	return crc;
32*4882a593Smuzhiyun }
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