Sam Grove / checksum

Utility functions for working with data streams

Example usage:

http://andy.dynamicbits.com/hdradio/

#include "mbed.h"
#include "checksum.h"

DigitalOut myled(LED1);

template <int T>
struct data{
    uint8_t buf[T];
    uint8_t checksum;
};

data<12> all_ones = {{1,1,1,1,1,1,1,1,1,1,1,1}};

int main() 
{
    calculateChecksum( all_ones.buf, sizeof(all_ones) );
      
    for(int i=0; i<sizeof(all_ones); i++)
    {
        printf("%02d: %d\n", i, *(all_ones.buf+i));
    }

    printf("checksum test: %s\n", (result)?"passed":"failed");

    while(1) 
    {
        myled = 1;
        wait(0.2);
        myled = 0;
        wait(0.2);
    }
}

Diff: checksum.h

Revision:
0:39b5762958a4
Child:
1:ace4b3aef52b
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/checksum.h	Thu Mar 07 20:55:29 2013 +0000
@@ -0,0 +1,80 @@
+/**
+ * @file    checksum.h
+ * @brief   Utility Function - Data integrity helpers
+ * @author  sam grove
+ * @version 1.0
+ *
+ * Copyright (c) 2013
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+ 
+/** Helpers for working data streams
+ *
+ * Example:
+ * @code
+ *  #include "mbed.h"
+ *  #include "checksum.h"
+ *
+ *  DigitalOut myled(LED1);
+ *  
+ *  template <int T>
+ *  struct data{
+ *      uint8_t buf[T];
+ *      uint8_t checksum;
+ *  };
+ *  data<12> all_ones = {{1,1,1,1,1,1,1,1,1,1,1,1}};
+ *
+ *  int main() 
+ *  {
+ *      calculateChecksum( all_ones.buf, sizeof(all_ones) );
+ *      
+ *      for(int i=0; i<sizeof(all_ones); i++)
+ *      {
+ *          printf("%02d: %d\n", i, *(all_ones.buf+i));
+ *      }
+ *
+ *      printf("checksum test: %s\n", (result)?"passed":"failed");
+ *
+ *      while(1) 
+ *      {
+ *          myled = 1;
+ *          wait(0.2);
+ *          myled = 0;
+ *          wait(0.2);
+ *      }
+ *  }
+ * @endcode
+ */
+ 
+#ifndef CHECKSUM_H
+#define CHECKSUM_H
+
+#include <stdint.h>
+
+/** Calculate the checksum of a data stream
+ *  Assumes the checksum is in the last position, 8-bits and 0 - the sum of data 
+ *  @param pkt - A pointer to the data
+ *  @param length - The amount of data that the checksum calculates
+ *  @returns true if the checksum is correct and false otherwise
+ */
+bool validateChecksum( uint8_t const *pkt, uint32_t const length );
+
+/** Calculate and store the checksum into the last position of a data stream
+ *
+ *  @param pkt - A pointer to the data
+ *  @param length - The amount of data that the checksum calculates
+ */
+void calculateChecksum( uint8_t *pkt, uint32_t const length );
+
+#endif