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 <s...@chromium.org>
Signed-off-by: Simon Glass <s...@chromium.org>
Reviewed-by: Simon Glass <s...@chromium.org>
---
include/linux/crc8.h | 23 +++++++++++++++++++++++
lib/Makefile | 1 +
lib/crc8.c | 25 +++++++++++++++++++++++++
3 files changed, 49 insertions(+)
create mode 100644 include/linux/crc8.h
create mode 100644 lib/crc8.c
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 4e3b500..bb9fcbf 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -14,6 +14,7 @@ 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;
+}
--
1.8.4.1
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