Diff: crc8.cpp

Revision:

0:1449f126b241

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/crc8.cpp	Sun Mar 03 01:41:51 2013 +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;
+}