/***************************************************************************
                          bpskmodulator.cpp  -  description
                             -------------------
    begin                : Mon Feb 24 2003
    copyright            : (C) 2003 by Volker Schroer
    email                : dl1ksv@gmx.de
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   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.                                   *
 *   The PSK part is based on WinPSK 1.0 by Moe Wheatly, AE4JY             *
 ***************************************************************************/

#include "bpskmodulator.h"
#include "constants.h"

#define SYM_NOCHANGE 0	//Stay the same phase
#define SYM_P180 2		//Plus 180 deg
#define SYM_OFF 4		//No output
#define SYM_ON 5		//constant output

BPSKModulator::BPSKModulator(int FS,double freq,CTxBuffer *TxBuffer):PSKModulator(FS,freq,TxBuffer)
{
}
BPSKModulator::~BPSKModulator()
{
}
char BPSKModulator::GetNextSymbol(void)
{
char symb;
int ch;
	symb = m_Lastsymb;
	if( m_TxShiftReg == 0 )
	{
		if( m_AddEndingZero )		// if is end of code
		{
			symb = SYM_P180;		// end with a zero
			m_AddEndingZero = false;
		}
		else
		{
			ch = GetChar();			//get next character to xmit
			if( ch >=0 )			//if is not a control code
			{						//get next VARICODE codeword to send
				m_TxShiftReg = VARICODE_TABLE[ ch&0xFF ];
				symb = SYM_P180;	//Start with a zero
			}
			else					// is a control code
			{
				switch( ch )
				{
				case TXON_CODE:
					symb = SYM_ON;
					break;
				case TXTOG_CODE:
					symb = SYM_P180;
					break;
				case TXOFF_CODE:
					symb = SYM_OFF;
					break;
				}
			}
		}
	}
	else			// is not end of code word so send next bit
	{
		if( m_TxShiftReg&0x8000 )
			symb = SYM_NOCHANGE;
		else
			symb = SYM_P180;
		m_TxShiftReg = m_TxShiftReg<<1;	//point to next bit
		if( m_TxShiftReg == 0 )			// if at end of codeword
			m_AddEndingZero = true;		// need to send a zero nextime
	}
	m_Lastsymb = symb;
	return symb;

}