monitor: Add functions for link layer CRC calculations

1 files changed, 84 insertions, 0 deletions

diff --git a/monitor/crc.c b/monitor/crc.c
new file mode 100644
index 000000000..9ea11fbf4
--- /dev/null
+++ b/monitor/crc.c
@@ -0,0 +1,84 @@
+/*
+ *
+ *  BlueZ - Bluetooth protocol stack for Linux
+ *
+ *  Copyright (C) 2011-2012  Intel Corporation
+ *  Copyright (C) 2004-2010  Marcel Holtmann <marcel@holtmann.org>
+ *
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "crc.h"
+
+uint32_t crc24_bit_reverse(uint32_t value)
+{
+	uint32_t result = 0;
+	uint8_t i;
+
+	for (i = 0; i < 24; i++)
+		result |= ((value >> i) & 1) << (23 - i);
+
+	return result;
+}
+
+uint32_t crc24_calculate(uint32_t preset, const uint8_t *data, uint8_t len)
+{
+	uint32_t state = preset;
+	uint8_t i;
+
+	for (i = 0; i < len; i++) {
+		uint8_t n, cur = data[i];
+
+		for (n = 0; n < 8; n++) {
+			int next_bit = (state ^ cur) & 1;
+
+			cur >>= 1;
+			state >>= 1;
+			if (next_bit) {
+				state |= 1 << 23;
+				state ^= 0x5a6000;
+			}
+		}
+	}
+
+	return state;
+}
+
+uint32_t crc24_reverse(uint32_t crc, const uint8_t *data, uint8_t len)
+{
+	uint32_t state = crc;
+	uint8_t i;
+
+	for (i = 0; i < len; i++) {
+		uint8_t n, cur = data[len - i - 1];
+
+		for (n = 0; n < 8; n++) {
+			int top_bit = state >> 23;
+
+			state = (state << 1) & 0xffffff;
+			state |= top_bit ^ ((cur >> (7 - n)) & 1);
+			if (top_bit)
+				state ^= 0xb4c000;
+		}
+	}
+
+	return state;
+}