vtg.cpp

来自「提取各种NEMA0183格式数据的类编程。」· C++ 代码 · 共 155 行

/*
** Author: Samuel R. Blackburn
** Internet: [e-mail]
**
** Copyright, 1996-2005, Samuel R. Blackburn
**
** "You can get credit for something or get it done, but not both."
** Dr. Richard Garwin
**
** BSD License follows.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
**
** Redistributions of source code must retain the above copyright notice,
** this list of conditions and the following disclaimer. Redistributions
** in binary form must reproduce the above copyright notice, this list
** of conditions and the following disclaimer in the documentation and/or
** other materials provided with the distribution. Neither the name of
** the WFC nor the names of its contributors may be used to endorse or
** promote products derived from this software without specific prior
** written permission.
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
**
** $Workfile: vtg.cpp $
** $Revision: 4 $
** $Modtime: 10/10/98 2:39p $
*/

#include "nmea0183.h"
#pragma hdrstop

#if defined( _DEBUG ) && defined( _INC_CRTDBG )
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#define new DEBUG_NEW
#endif // _DEBUG

VTG::VTG()
{
   Mnemonic = TEXT( "VTG" );
   Empty();
}

VTG::~VTG()
{
   Mnemonic.Empty();
   Empty();
}

void VTG::Empty( void )
{
   TrackDegreesTrue       = 0.0;
   TrackDegreesMagnetic   = 0.0;
   SpeedKnots             = 0.0;
   SpeedKilometersPerHour = 0.0;
   FAAMode                = FAAModeUnknown;
}

BOOL VTG::Parse( const SENTENCE& sentence )
{
   /*
   ** VTG - Track made good and Ground speed
   **
   **        1   2 3   4 5	  6 7   8 9
   **        |   | |   | |	  | |   | |
   ** $--VTG,x.x,T,x.x,M,x.x,N,x.x,K*hh<CR><LF>
   **
   ** Field Number: 
   **  1) Track Degrees
   **  2) T = True
   **  3) Track Degrees
   **  4) M = Magnetic
   **  5) Speed Knots
   **  6) N = Knots
   **  7) Speed Kilometers Per Hour
   **  8) K = Kilometers Per Hour
   **  9) Checksum
   */

   /*
   ** First we check the checksum...
   */

   const NMEA0183_BOOLEAN checksum_is_bad = sentence.IsChecksumBad();

   if ( checksum_is_bad == True )
   {
      InvalidChecksum();
      return( FALSE );
   } 

   TrackDegreesTrue       = sentence.Double( 1 );
   TrackDegreesMagnetic   = sentence.Double( 3 );
   SpeedKnots             = sentence.Double( 5 );
   SpeedKilometersPerHour = sentence.Double( 7 );

   const int checksum_field_number = sentence.ChecksumFieldNumber();

   if ( checksum_field_number == 9 )
   {
      FAAMode = sentence.FAAMode( 8 );
   }
   else
   {
      FAAMode = FAAModeUnknown;
   }

   return( TRUE );
}

BOOL VTG::Write( SENTENCE& sentence )
{
   /*
   ** Let the parent do its thing
   */
   
   RESPONSE::Write( sentence );

   sentence += TrackDegreesTrue;
   sentence += TEXT( "T" );
   sentence += TrackDegreesMagnetic;
   sentence += TEXT( "M" );
   sentence += SpeedKnots;
   sentence += TEXT( "N" );
   sentence += SpeedKilometersPerHour;
   sentence += TEXT( "K" );

   sentence.Finish();

   return( TRUE );
}

const VTG& VTG::operator = ( const VTG& source )
{
   TrackDegreesTrue       = source.TrackDegreesTrue;
   TrackDegreesMagnetic   = source.TrackDegreesMagnetic;
   SpeedKnots             = source.SpeedKnots;
   SpeedKilometersPerHour = source.SpeedKilometersPerHour;

   return( *this );
}