Added a function for computing the CRC16 over a portion of data

core/lib/crc16.c

@@ -28,7 +28,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * @(#)$Id: crc16.c,v 1.1 2006/06/17 22:41:17 adamdunkels Exp $
+ * @(#)$Id: crc16.c,v 1.2 2008/07/07 23:24:36 adamdunkels Exp $
  */
 
 /** \addtogroup crc16
@@ -63,5 +63,18 @@ crc16_add(unsigned char b, unsigned short acc)
   return acc;
 }
 /*---------------------------------------------------------------------------*/
+unsigned short
+crc16_data(unsigned char *data, int len, unsigned short acc)
+{
+  int i;
+  unsigned short crc = 0;
+  
+  for(i = 0; i < len; ++i) {
+    crc = crc16_add(*data, crc);
+    ++data;
+  }
+  return crc;
+}
+/*---------------------------------------------------------------------------*/
 
 /** @} */

core/lib/crc16.h

@@ -50,7 +50,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * @(#)$Id: crc16.h,v 1.1 2006/06/17 22:41:17 adamdunkels Exp $
+ * @(#)$Id: crc16.h,v 1.2 2008/07/07 23:24:36 adamdunkels Exp $
  */
 #ifndef __CRC16_H__
 #define __CRC16_H__
@@ -73,6 +73,23 @@
  */
 unsigned short crc16_add(unsigned char b, unsigned short crc);
 
+/**
+ * \brief      Calculate the CRC16 over a data area
+ * \param data Pointer to the data
+ * \param datalen The length of the data
+ * \param crc  The accumulated CRC that is to be updated (or zero).
+ * \return     The CRC16 checksum.
+ *
+ *             This function calculates the CRC16 checksum of a data area.
+ *
+ *             \note The algorithm used in this implementation is
+ *             tailored for a running checksum and does not perform as
+ *             well as a table-driven algorithm when checksumming an
+ *             entire data block.
+ */
+unsigned short crc16_data(unsigned char *data, int datalen,
+			  unsigned short acc);
+
 #endif /* __CRC16_H__ */
 
 /** @} */