diff options
| -rw-r--r-- | include/linux/crc8.h | 23 | ||||
| -rw-r--r-- | lib/Makefile | 1 | ||||
| -rw-r--r-- | lib/crc8.c | 25 |
3 files changed, 49 insertions, 0 deletions
diff --git a/include/linux/crc8.h b/include/linux/crc8.h new file mode 100644 index 0000000..b5fd2ac --- /dev/null +++ b/include/linux/crc8.h @@ -0,0 +1,23 @@ +/* + * Copyright (c) 2013 Google, Inc + * + * SPDX-License-Identifier: GPL-2.0+ + */ + + +#ifndef __linux_crc8_h +#define __linux_crc8_h + +/** + * crc8() - Calculate and return CRC-8 of the data + * + * This uses an x^8 + x^2 + x + 1 polynomial. A table-based algorithm would + * be faster, but for only a few bytes it isn't worth the code size + * + * @vptr: Buffer to checksum + * @len: Length of buffer in bytes + * @return CRC8 checksum + */ +unsigned int crc8(const unsigned char *vptr, int len); + +#endif diff --git a/lib/Makefile b/lib/Makefile index e787f77..760340f 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -21,6 +21,7 @@ obj-$(CONFIG_BZIP2) += bzlib_randtable.o obj-$(CONFIG_BZIP2) += bzlib_huffman.o obj-$(CONFIG_USB_TTY) += circbuf.o obj-y += crc7.o +obj-y += crc8.o obj-y += crc16.o obj-$(CONFIG_OF_CONTROL) += fdtdec.o obj-$(CONFIG_TEST_FDTDEC) += fdtdec_test.o diff --git a/lib/crc8.c b/lib/crc8.c new file mode 100644 index 0000000..8b68a29 --- /dev/null +++ b/lib/crc8.c @@ -0,0 +1,25 @@ +/* + * Copyright (c) 2013 Google, Inc + * + * SPDX-License-Identifier: GPL-2.0+ + */ + +#include "linux/crc8.h" + +unsigned int crc8(const unsigned char *vptr, int len) +{ + const unsigned char *data = vptr; + unsigned int crc = 0; + int i, j; + + for (j = len; j; j--, data++) { + crc ^= (*data << 8); + for (i = 8; i; i--) { + if (crc & 0x8000) + crc ^= (0x1070 << 3); + crc <<= 1; + } + } + + return (crc >> 8) & 0xff; +} |