Diff: crc8.cpp

Revision:

0:1197076b78f4

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/crc8.cpp	Mon May 10 08:14:32 2010 +0000
@@ -0,0 +1,39 @@
+#include <inttypes.h>
+
+#define CRC8INIT	0x00
+#define CRC8POLY	0x18              //0X18 = X^8+X^5+X^4+X^0
+
+uint8_t	crc8 ( uint8_t *data_in, uint16_t number_of_bytes_to_read )
+{
+	uint8_t	 crc;
+	uint16_t loop_count;
+	uint8_t  bit_counter;
+	uint8_t  data;
+	uint8_t  feedback_bit;
+	
+	crc = CRC8INIT;
+
+	for (loop_count = 0; loop_count != number_of_bytes_to_read; loop_count++)
+	{
+		data = data_in[loop_count];
+		
+		bit_counter = 8;
+		do {
+			feedback_bit = (crc ^ data) & 0x01;
+	
+			if ( feedback_bit == 0x01 ) {
+				crc = crc ^ CRC8POLY;
+			}
+			crc = (crc >> 1) & 0x7F;
+			if ( feedback_bit == 0x01 ) {
+				crc = crc | 0x80;
+			}
+		
+			data = data >> 1;
+			bit_counter--;
+		
+		} while (bit_counter > 0);
+	}
+	
+	return crc;
+}