ArNetPacket.cpp

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/*
MobileRobots Advanced Robotics Interface for Applications (ARIA)
Copyright (C) 2004, 2005 ActivMedia Robotics LLC
Copyright (C) 2006, 2007 MobileRobots Inc.

     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 
MobileRobots for information about a commercial version of ARIA at 
robots@mobilerobots.com or 
MobileRobots Inc, 19 Columbia Drive, Amherst, NH 03031; 800-639-9481
*/

#include "Aria.h"
#include "ArExport.h"
#include "ArNetPacket.h"

AREXPORT ArNetPacket::ArNetPacket(ArTypes::UByte2 bufferSize) :
  ArBasePacket(bufferSize, ArNetPacket::HEADER_LENGTH, NULL, ArNetPacket::FOOTER_LENGTH)
{
  myCommand = 0;
  myAddedFooter = false;
}

AREXPORT ArNetPacket::~ArNetPacket()
{

}

AREXPORT void ArNetPacket::doubleToBuf(double val)
{
  char buf[256];
  if (val == -HUGE_VAL)
        sprintf(buf, "-INF");
  else if (val == HUGE_VAL)
        sprintf(buf, "INF");
  else
        sprintf(buf, "%g", val);
  strToBuf(buf);
}

AREXPORT double ArNetPacket::bufToDouble(void)
{
  char buf[256];
  char *endPtr;
  double ret;

  bufToStr(buf, sizeof(buf));
  if (strncmp(buf, "-INF", sizeof(buf)) == 0)
  {
        ret = -HUGE_VAL;
        return ret;
  }
  else if (strncmp(buf, "INF", sizeof(buf)) == 0)
  {
        ret = HUGE_VAL;
        return ret;
  }
  else
  {
        ret = strtod(buf, &endPtr);
        if (endPtr[0] == '\0' && endPtr != buf)
          return ret;
        else
      return 0;
  }
}

AREXPORT void ArNetPacket::empty(void)
{
  myCommand = 0;
  myLength = myHeaderLength;
  myAddedFooter = false;
  resetValid();
}

AREXPORT void ArNetPacket::finalizePacket(void)
{
  int length;
  length = myLength;
  int chkSum;

  myLength = 0;
  uByteToBuf(0xF);
  uByteToBuf(0xC);
  if (myAddedFooter)
    uByte2ToBuf(length);
  else
    uByte2ToBuf(length+2);
  uByte2ToBuf(myCommand);
  if (myAddedFooter)
    myLength = length - 2;
  else
    myLength = length;
  chkSum = calcCheckSum();
  byteToBuf((chkSum >> 8) & 0xff );
  byteToBuf(chkSum & 0xff );
  myAddedFooter = true;
  //log();
  //printf("%d %d %d\n", myLength ,myCommand, chkSum);
}

AREXPORT void ArNetPacket::resetRead(void)
{
  myReadLength = 4;
  myCommand = bufToUByte2();
  myReadLength = myHeaderLength;
  resetValid();

}

AREXPORT void ArNetPacket::setCommand(ArTypes::UByte2 command)
{
  myCommand = command;
}

AREXPORT ArTypes::UByte2 ArNetPacket::getCommand(void)
{
  return myCommand;
}

AREXPORT void ArNetPacket::duplicatePacket(ArNetPacket *packet)
{
  myLength = packet->myLength;
  if (myMaxLength < myLength)
    setMaxLength(packet->myLength);
  myReadLength = packet->myReadLength;
  myHeaderLength = packet->myHeaderLength;
  myFooterLength = packet->myFooterLength;
  myCommand = packet->myCommand;
  myAddedFooter = packet->myAddedFooter;
  memcpy(myBuf, packet->getBuf(), packet->myLength + packet->myFooterLength);
}

AREXPORT ArTypes::Byte2 ArNetPacket::calcCheckSum(void)
{
  int i;
  int n;
  int c = 0;

  //printf("%d\n", myLength); 
  //log();
  i = 3;
  n = myLength - 2;
  while (n > 3) {
    //printf("n %d i %d c %d c1 %d c2 %d\n", n, i, c, myBuf[i], myBuf[i+1]);
    c += ((unsigned char)myBuf[i]<<8) | (unsigned char)myBuf[i+1];
    c = c & 0xffff;
    n -= 2;
    i += 2;
  }
  //printf("aft n %d i %d c %d\n", n, i, c);
  if (n > 0) 
    c = c ^ (int)((unsigned char) myBuf[i]);
  //printf("%d\n", c);
  return c;
}

AREXPORT bool ArNetPacket::verifyCheckSum(void) 
{
  ArTypes::Byte2 chksum;
  ArTypes::Byte2 calcedChksum;
  unsigned char c1, c2;
  int length;

  if (myLength - 2 < myHeaderLength)
    return false;

  c2 = myBuf[myLength-2];
  c1 = myBuf[myLength-1];
  chksum = (c1 & 0xff) | (c2 << 8);
  length = myLength;
  myLength = myLength - 2;
  calcedChksum = calcCheckSum();
  myLength = length;

  //printf("%d %d\n", chksum, calcedChksum);
  if (chksum == calcedChksum) {
    return true;
  } else {
    return false;
  }
  
}

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