common.c

/**************************************************************************
 *
 * FILE NAME:            common.c
 * FILE DESCRIPTION:    Common routines
 *
 * FILE CREATION DATE:    24-05-2004
 *
 *==========================================================================
 *           Copyright (c) 2004 NIR Diagnostics Inc., Ontario, Canada
 *
 * This document contains confidential information which is protected by
 * copyright and is proprietary to NIR Diagnostics Inc., Ontario, Canada. No part
 * of this document may be used, copied, disclosed, or conveyed to another
 * party without prior written consent of NIR Diagnostics Inc., Ontario, Canada.
 ***************************************************************************
 *
 * Modification history:
 * --------------------
 * 01a,24may03 erd    written
 *
 ***************************************************************************/

#include "sysdef.h"
#include "common.h"
#include "sys.h"

// for time delays
unsigned char time_delayUsLeft;

// ==========================================================================
// uint_8 sys_calculateChecksum(uint_8 *buffer, uint_8 size)
//
// Caluclates an 1's complement checksum over contents of buffer
// 
// Arguments:
//    buffer: ptr to start of buffer on which chksum is calculated over
//    size: size, in bytes, of buffer
//
// Return value:
//    checksum value
//
uint_8 sys_calculateChecksum(uint_8 *buffer, uint_8 size)
{
    uint_8 chksum = 0;

    // calculate the checksum over the buffer
    while (size--) 
    {
        chksum += *buffer;
        buffer++;
    }

    // return the checksum
    return (~chksum + 1);
}
// ==========================================================================
// uint_16 calculateChecksum16(uint_8 *buffer, uint_16 size)
//
// Caluclates an 16bit checksum over contents of buffer
// 
// Arguments:
//    buffer: ptr to start of buffer on which chksum is calculated over
//    size: size, in bytes, of buffer
//
// Return value:
//    checksum value
//

uint_16 sys_calculateChecksum16(uint_8 *buffer, uint_16 size)
{
    uint_16 chksum = 0;

    // calculate the checksum over the buffer
    while (size--) 
    {
        chksum += *buffer;
        buffer++;
    }

    // return the checksum
    return (~chksum + 1);
}

// ==========================================================================
// void time_delayMs(int_16 ms)
//
// delay one mS
//
// Arguments:
//    ms: the amount of miliseconds to delay
// 

void time_delayMs(int_16 ms)
{
    uint_8 i;

    do 
    {
        // reset i
        i = 4;
        
        do 
        {
            // delay a quarter of a ms
            time_delayUs(250);
            CLRWDT();
        
        } while(--i);
    

    } while(--ms);
}