nmeaparser.cpp

SYMBIAN GPS NMEA协议实现

/************************************************************************/
/* Bluteooth Test           The.Berlin.Factor                 Juni 2003 */
/************************************************************************/

#include <E32Math.h>

#include "gps/nmea/NmeaParser.h"



void CNmeaParser::SetData( TDesC8 & aNmeaMessage ) {

	iMessage = &aNmeaMessage;
	iParsePosition = 0;

}



void CNmeaParser::GetNextTokenIntoL( TDes8 & aBuffer ) {

	if ( iMessage == NULL )
		User::Leave( KErrNotReady );

	if ( iParsePosition >= iMessage->Length( ) )
		User::Leave( KErrNotFound );

	while ( iParsePosition < iMessage->Length( ) ) {

		TUint8 nextChar = ( *iMessage )[ iParsePosition++ ];

		if ( nextChar == ',' )
			break;

		aBuffer.Append( nextChar );
	}

}



void CNmeaParser::SkipNextTokenL( ) {

	if ( iMessage == NULL )
		User::Leave( KErrNotReady );

	if ( iParsePosition >= iMessage->Length( ) )
		User::Leave( KErrNotFound );

	while ( iParsePosition < iMessage->Length( ) ) {

		TUint8 nextChar = ( *iMessage )[ iParsePosition++ ];

		if ( nextChar == ',' )
			break;
	}

}



TReal CNmeaParser::GetNextTokensAsLatitudeL( ) {

	TReal angle;

	TBuf8< 15 > angleString;
	GetNextTokenIntoL( angleString );

	TBuf8< 5 > northSouth;
	GetNextTokenIntoL( northSouth );

	TLex8 latLexer( angleString );
	TInt error = latLexer.Val( angle, '.' );

	if ( error != KErrNone )
		User::Leave( error );

	TInt32 degrees;
	Math::Int( degrees, angle / 100.0 );

	TInt32 minutes;
	Math::Int( minutes, angle - degrees * 100 );

	TReal decimal;
	Math::Frac( decimal, angle );

	TReal latitude = degrees + ( minutes + decimal ) / 60.0;

	if ( northSouth[ 0 ] == 'S' )
		latitude = -latitude;

	return( latitude );

}



TReal CNmeaParser::GetNextTokensAsLongitudeL( ) {

	TReal angle;

	TBuf8< 15 > angleString;
	GetNextTokenIntoL( angleString );

	TBuf8< 5 > northSouth;
	GetNextTokenIntoL( northSouth );

	TLex8 latLexer( angleString );
	TInt error = latLexer.Val( angle, '.' );

	if ( error != KErrNone )
		User::Leave( error );

	TInt32 degrees;
	Math::Int( degrees, angle / 100.0 );

	TInt32 minutes;
	Math::Int( minutes, angle - degrees * 100 );

	TReal decimal;
	Math::Frac( decimal, angle );

	TReal longitude = degrees + ( minutes + decimal ) / 60.0;

	if ( northSouth[ 0 ] == 'W' )
		longitude = -longitude;

	return( longitude );

}



TInt CNmeaParser::GetNextTokenAsIntL( ) {

	TInt result = 0;

	TBuf8< 10 > intString;
	GetNextTokenIntoL( intString );

	TLex8 lexer( intString );
	User::LeaveIfError( lexer.Val( result ) );

	return( result );

}



TReal CNmeaParser::GetNextTokenAsRealL( ) {

	TReal result = 0;

	TBuf8< 10 > realString;
	GetNextTokenIntoL( realString );

	TLex8 lexer( realString );
	User::LeaveIfError( lexer.Val( result ) );

	return( result );

}



void CNmeaParser::ClearData( ) {

	iMessage = NULL;
	iParsePosition = 0;

}