ArSickPacket.cpp

/*
ActivMedia Robotics Interface for Applications (ARIA)
Copyright (C) 2004,2005 ActivMedia Robotics, LLC


     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation; either version 2 of the License, or
     (at your option) any later version.

     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with this program; if not, write to the Free Software
     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

If you wish to redistribute ARIA under different terms, contact 
ActivMedia Robotics for information about a commercial version of ARIA at 
robots@activmedia.com or 
ActivMedia Robotics, 19 Columbia Drive, Amherst, NH 03031; 800-639-9481

*/

#include "ArExport.h"
#include "ariaOSDef.h"
#include "ArSickPacket.h"
#include "stdio.h"

ArSickPacket::ArSickPacket(unsigned char sendingAddress) :
  ArBasePacket(2048, 4)
{
  mySendingAddress = sendingAddress;
}

ArSickPacket::~ArSickPacket()
{
}

void ArSickPacket::setSendingAddress(unsigned char address)
{
  mySendingAddress = address;
}

unsigned char ArSickPacket::getSendingAddress(void)
{
  return mySendingAddress;
}

unsigned char ArSickPacket::getReceivedAddress(void)
{
  int len = myReadLength;
  unsigned char address;
  
  // toss it into the second byte of the packet
  myReadLength = 1;
  address = bufToUByte();
  myLength = len;
  return address;
}

ArTypes::UByte ArSickPacket::getID(void)
{
 if (myLength >= 5)
    return myBuf[4];
  else
    return 0;
}

void ArSickPacket::resetRead(void)
{
  myReadLength = myHeaderLength + 1;
}

void ArSickPacket::finalizePacket(void)
{
  int len = myLength;
  int chkSum;

  // put in the start of the packet
  myLength = 0;
  // toss in the header 
  uByteToBuf(0x02);
  // now the laser we want to talk to
  uByteToBuf(mySendingAddress);
  // dump in the length
  uByte2ToBuf(len - myHeaderLength);
  myLength = len;

  // that lovely CRC
  chkSum = calcCRC();
  byteToBuf(chkSum & 0xff );
  byteToBuf((chkSum >> 8) & 0xff );

  //printf("Sending ");
  //log();
}

void ArSickPacket::duplicatePacket(ArSickPacket *packet)
{
  myLength = packet->getLength();
  myReadLength = packet->getReadLength();
  myTimeReceived = packet->getTimeReceived();
  mySendingAddress = packet->getSendingAddress();
  memcpy(myBuf, packet->getBuf(), myLength);
  
}

ArTypes::Byte2 ArSickPacket::calcCRC(void)
{
  unsigned short uCrc16;
  unsigned char abData[2];
  unsigned int uLen = myLength;
  unsigned char * commData = (unsigned char *)myBuf;

  uCrc16 = 0;
  abData[0] = 0;
  while (uLen--)
  {
    abData[1] = abData[0];
    abData[0] = *commData++;
    if (uCrc16 & 0x8000)
    {
      uCrc16 = (uCrc16 & 0x7fff) << 1;
      uCrc16 ^= 0x8005;
    }
    else
    {
      uCrc16 <<= 1;
    }
    uCrc16 ^= ((unsigned short) abData[0] | 
               ((unsigned short)(abData[1]) << 8));
  }
  return uCrc16;
}

bool ArSickPacket::verifyCRC(void) 
{
  int readLen = myReadLength;
  int len = myLength;
  ArTypes::Byte2 chksum;
  unsigned char c1, c2;

  myReadLength = myLength - 2;
  
  if (myReadLength < myHeaderLength)
    return false;

  c1 = bufToByte();
  c2 = bufToByte();
  myReadLength = readLen;
  chksum = (c1 & 0xff) | (c2 << 8);

  myLength = myLength - 2;
  if (chksum == calcCRC()) {
    myLength = len;
    return true;
  } else {
    myLength = len;
    return false;
  }
  
}

ArTime ArSickPacket::getTimeReceived(void)
{
  return myTimeReceived;
}

void ArSickPacket::setTimeReceived(ArTime timeReceived)
{
  myTimeReceived = timeReceived;
}

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