Diff: crc16.cpp

Revision:

0:5d39f2521173

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/crc16.cpp	Mon Mar 09 11:55:54 2015 +0000
@@ -0,0 +1,56 @@
+#include <inttypes.h>
+#include "mbed.h"
+#include "onewire.h"
+
+#define CRC16INIT    0x0000
+//#define CRC16POLY    0x8005; // Polynome =x^16 + x^15 + x^2 + x^0 = 0x18005
+#define CRC16POLY    0xA001;
+
+uint16_t crc16(uint8_t* octets, uint16_t nboctets)
+{
+uint16_t crc = CRC16INIT;
+int i, done = 0;
+uint8_t todo;
+    if (nboctets != 0) {
+        do {
+            todo = octets[done];
+            crc ^= todo;
+            for (i = 0; i < 8; i++) {
+                if (crc % 2 != 0) {
+                    crc = (crc >> 1) ^ CRC16POLY;
+                } else {
+                    crc = crc >> 1;
+                }
+            }
+            done++;
+        } while (done < nboctets);
+        
+        
+    }
+
+return crc;
+}
+//CRC16 byte, always two bytes, bit inverted, LSByte first 
+uint8_t ctrl_crc16(uint8_t* octets, uint16_t nboctets)
+{
+    uint16_t crc;
+    uint8_t *ptr;
+#ifdef DEBUG
+    printf( "\nCRC16 : " );
+    for ( uint8_t i=0 ; i< nboctets; i++ )
+        printf(":%2.2X",octets[i]);
+    printf( "\n" );
+#endif
+    crc =~crc16(octets, nboctets-2);
+    ptr=(uint8_t*)&crc;
+#ifdef DEBUG
+    printf( "\n" );
+    printf("CRC16:%X",crc);
+    printf( "\n" );
+#endif
+    if(*ptr==octets[nboctets-2])
+        if(*++ptr==octets[nboctets-1])
+            return 0;
+
+    return 1;
+ } 
\ No newline at end of file