Add crc8 routine

Add an implementation of the CRC8 algorithm. This is required by the TPM emulation, but is probably useful to U-Boot in general. Signed-off-by: Simon Glass <sjg@chromium.org> Signed-off-by: Simon Glass <sjg@chromium.org> Reviewed-by: Simon Glass <sjg@chromium.org>

Add crc8 routine
Add an implementation of the CRC8 algorithm. This is required by the TPM emulation, but is probably useful to U-Boot in general. Signed-off-by: Simon Glass <sjg@chromium.org> Signed-off-by: Simon Glass <sjg@chromium.org> Reviewed-by: Simon Glass <sjg@chromium.org>
Simon Glass
1 parent e7be18225f
Showing 3 changed files with 49 additions and 0 deletions Side-by-side Diff
include/linux/crc8.h
lib/Makefile
lib/crc8.c
+/*
+ * 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
@@ -21,6 +21,7 @@
 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
+/*
+ * 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;
+}
	1	+/*
	2	+ * Copyright (c) 2013 Google, Inc
	3	+ *
	4	+ * SPDX-License-Identifier: GPL-2.0+
	5	+ */
	6	+
	7	+
	8	+#ifndef __linux_crc8_h
	9	+#define __linux_crc8_h
	10	+
	11	+/**
	12	+ * crc8() - Calculate and return CRC-8 of the data
	13	+ *
	14	+ * This uses an x^8 + x^2 + x + 1 polynomial. A table-based algorithm would
	15	+ * be faster, but for only a few bytes it isn't worth the code size
	16	+ *
	17	+ * @vptr: Buffer to checksum
	18	+ * @len: Length of buffer in bytes
	19	+ * @return CRC8 checksum
	20	+ */
	21	+unsigned int crc8(const unsigned char *vptr, int len);
	22	+
	23	+#endif
...	...	@@ -21,6 +21,7 @@
21	21	obj-$(CONFIG_BZIP2) += bzlib_huffman.o
22	22	obj-$(CONFIG_USB_TTY) += circbuf.o
23	23	obj-y += crc7.o
	24	+obj-y += crc8.o
24	25	obj-y += crc16.o
25	26	obj-$(CONFIG_OF_CONTROL) += fdtdec.o
26	27	obj-$(CONFIG_TEST_FDTDEC) += fdtdec_test.o