gsv.cpp

来自「提取各种NEMA0183格式数据的类编程。」· C++ 代码 · 共 167 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: gsv.cpp $
** $Revision: 5 $
** $Modtime: 10/10/98 2:48p $
*/

#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

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

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

void GSV::Empty( void )
{
  
   NumberOfSatellites = 0;

   int index = 0;

   while( index < 12 )
   {
      SatellitesInView[ index ].Empty();
      index++;
   }
}

BOOL GSV::Parse( const SENTENCE& sentence )
{
   /*
   ** GSV - TRANSIT Position - Latitude/Longitude
   ** Location and time of TRANSIT fix at waypoint
   **
   **        1 2 3  4  5  6   7  8  9  10  11 12 13 14  15 16 17 18  19  20
   **        | | |  |  |  |   |  |  |  |   |  |  |  |   |  |  |  |   |   |
   ** $--GSV,x,x,xx,xx,xx,xxx,xx,xx,xx,xxx,xx,xx,xx,xxx,xx,xx,xx,xxx,xx,*hh<CR><LF>
   **
   **  1) Total number of messages, 1-3
   **  2) Message Number, 1-3
   **  3) Total number of satellites in view
   **  4) Satellite Number #1
   **  5) Elevation #1
   **  6) Azimuth, Degrees True #1
   **  7) SNR #1, NULL when not tracking
   **  8) Satellite Number #2
   **  9) Elevation #2
   ** 10) Azimuth, Degrees True #2
   ** 11) SNR #2, NULL when not tracking
   ** 12) Satellite Number #3
   ** 13) Elevation #3
   ** 14) Azimuth, Degrees True #3
   ** 15) SNR #3, NULL when not tracking
   ** 16) Satellite Number #4
   ** 17) Elevation #4
   ** 18) Azimuth, Degrees True #4
   ** 19) SNR #4, NULL when not tracking
   ** 20) Checksum
   */  

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

   const NMEA0183_BOOLEAN checksum_is_bad = sentence.IsChecksumBad();

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

   int message_number = sentence.Integer( 2 );

   NumberOfSatellites = sentence.Integer( 3 );

   int index = 0;

   while( index < 4 )
   {
      SatellitesInView[ ( ( message_number - 1 ) * 4 ) + index ].Parse( ( index * 4 ) + 4, sentence );
      index++;
   }

   return( TRUE );
}

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

   /*
   ** OK, this is a hack, I'll figure out how to do multiple messages later
   */

   sentence.Finish();

   return( TRUE );
}

const GSV& GSV::operator = ( const GSV& source )
{
   NumberOfSatellites = source.NumberOfSatellites;

   int index = 0;

   while( index < 12 )
   {
      SatellitesInView[ index ] = source.SatellitesInView[ index ];
      index++;
   }

   return( *this );
}