Allow xmit of EOT character

* Still retains use of " ^r " in the user window
  * Covers special-case for FLARQ usage where ETX should
    stop the modem
  * EOT character can  now be transmitted from Tx window instead
    of switching to Rx mode
  * From: Andrej Lajovic <s57ln@hamradio.si>
    - Substitute symbolic names for negative return values of
      get_tx_char()

src/blank/blank.cxx

@@ -204,9 +204,9 @@ int xmtbyte;
 
 	case TX_STATE_DATA:
 		xmtbyte = get_tx_char();
-		if (xmtbyte == -1)
+		if (xmtbyte == GET_TX_CHAR_NODATA)
 			sendidle();
-		else if ( xmtbyte == 0x03 || stopflag)
+		else if ( xmtbyte == GET_TX_CHAR_ETX || stopflag)
 			txstate = TX_STATE_FLUSH;
 		else
 			sendchar(xmtbyte);

src/contestia/contestia.cxx

@@ -160,14 +160,14 @@ int contestia::tx_process()
 // to read any more. If stopflag is set, we will always read 
 // whatever there is.
 	if (stopflag || (Tx->GetReadReady() < Tx->BitsPerSymbol)) {
-		if (!stopflag && (c = get_tx_char()) == 0x03)
+		if (!stopflag && (c = get_tx_char()) == GET_TX_CHAR_ETX)
 			stopflag = true;
 		if (stopflag)
 			Tx->Stop();
 		else {
+			if (c == GET_TX_CHAR_NODATA)
+		                c = 0;
 			/* Replace un-representable characters with a dot */
-			if (c == -1)
-                c = 0;
 			if (c > (progdefaults.contestia8bit ? 255 : 127))
 				c = '.';
 			if (c > 127) {

src/cw_rtty/cw.cxx

@@ -1169,7 +1169,7 @@ int cw::tx_process()
 	}
 
 	c = get_tx_char();
-	if (c == 0x03 || stopflag) {
+	if (c == GET_TX_CHAR_ETX || stopflag) {
 		send_symbol(0, symbollen);
 		stopflag = false;
 			return -1;

src/cw_rtty/rtty.cxx

@@ -762,7 +762,7 @@ int rtty::tx_process()
 	c = get_tx_char();
 
 // TX buffer empty
-	if (c == 3 || stopflag) {
+	if (c == GET_TX_CHAR_ETX || stopflag) {
 		stopflag = false;
 		line_char_count = 0;
 		if (nbits != 5) {
@@ -780,7 +780,7 @@ int rtty::tx_process()
 	}
 
 // send idle character if c == -1
-	if (c == -1) {
+	if (c == GET_TX_CHAR_NODATA) {
 		send_idle();
 		return 0;
 	}

src/dialogs/fl_digi.cxx

@@ -6353,14 +6353,21 @@ int get_tx_char(void)
 	enum { STATE_CHAR, STATE_CTRL };
 	static int state = STATE_CHAR;
 
-	if (!que_ok) { return -1; }
-	if (Qwait_time) { return -1; }
-	if (Qidle_time) { return -1; }
-	if (macro_idle_on) { return -1; }
-	if (idling) { return -1; }
-
-	if (arq_text_available)
-		return (arq_get_char() & 0xFF);
+	if (!que_ok) { return GET_TX_CHAR_NODATA; }
+	if (Qwait_time) { return GET_TX_CHAR_NODATA; }
+	if (Qidle_time) { return GET_TX_CHAR_NODATA; }
+	if (macro_idle_on) { return GET_TX_CHAR_NODATA; }
+	if (idling) { return GET_TX_CHAR_NODATA; }
+	
+	if (arq_text_available) {
+		char character = (arq_get_char() & 0xFF);
+		if (character == 0x03) {
+			// ETX (0x03) in ARQ data means "stop transmitting" not "send ETX"
+			return(GET_TX_CHAR_ETX);
+		}
+		else
+			return(character);
+	}
 
 	if (active_modem == cw_modem && progdefaults.QSKadjust)
 		return szTestChar[2 * progdefaults.TestChar];
@@ -6369,7 +6376,7 @@ int get_tx_char(void)
 		 !idling ) {
 		Fl::add_timeout(progStatus.repeatIdleTime, get_tx_char_idle);
 		idling = true;
-		return -1;
+		return GET_TX_CHAR_NODATA;
 	}
 
 	int c;
@@ -6398,7 +6405,7 @@ int get_tx_char(void)
 	
 	if (c == -1) {
 		queue_reset();
-		return(-1);
+		return(GET_TX_CHAR_NODATA);
 	}
 	
 	if (state == STATE_CTRL) {
@@ -6407,33 +6414,33 @@ int get_tx_char(void)
 		switch (c) {
 		case 'r':
 			REQ_SYNC(&FTextTX::clear_sent, TransmitText);
-			return(3); // ETX
+			return(GET_TX_CHAR_ETX);
 			break;
 		case 'R':
 			if (TransmitText->eot()) {
 				REQ_SYNC(&FTextTX::clear_sent, TransmitText);
-				return(3); // ETX
+				return(GET_TX_CHAR_ETX);
 			} else
-				return(-1);
+				return(GET_TX_CHAR_NODATA);
 			break;
 		case 'L':
 			REQ(qso_save_now);
-			return(-1);
+			return(GET_TX_CHAR_NODATA);
 			break;
 		case 'C':
 			REQ(clearQSO);
-			return(-1);
+			return(GET_TX_CHAR_NODATA);
 			break;
 		case '!':
 			if (queue_must_rx()) {
 				que_timeout = 400; // 20 seconds
 				REQ(queue_execute_after_rx, (void *)0);
 				while(que_waiting) MilliSleep(1);
-				return(3);
+				return(GET_TX_CHAR_ETX);
 			} else {
 				REQ(do_que_execute, (void*)0);
 				while(que_waiting) MilliSleep(1);
-				return(-1);
+				return(GET_TX_CHAR_NODATA);
 			}
 			break;
 		default:
@@ -6454,8 +6461,10 @@ int get_tx_char(void)
 	transmit:
 	
 	c = tx_encoder.pop();
-	if (c == -1)
+	if (c == -1) {
 		LOG_ERROR("TX encoding conversion error: pushed content, but got nothing back");
+		return(GET_TX_CHAR_NODATA);
+	}
 
 	return(c);
 }

src/dominoex/dominoex.cxx

@@ -720,9 +720,9 @@ int dominoex::tx_process()
 		break;
 	case TX_STATE_DATA:
 		i = get_tx_char();
-		if (i == -1)
+		if (i == GET_TX_CHAR_NODATA)
 			sendsecondary();
-		else if (i == 3)
+		else if (i == GET_TX_CHAR_ETX)
 			txstate = TX_STATE_END;
 		else
 			sendchar(i, 0);

src/feld/feld.cxx

@@ -575,7 +575,7 @@ int feld::tx_process()
 
 	c = get_tx_char();
 
-	if (c == 0x03 || stopflag) {
+	if (c == GET_TX_CHAR_ETX || stopflag) {
 		tx_state = POSTAMBLE;
 		postamble = 3;
 		return 0;
@@ -583,7 +583,7 @@ int feld::tx_process()
 
 // if TX buffer empty
 // send idle character
-	if (c == -1) {
+	if (c == GET_TX_CHAR_NODATA) {
 		if (progdefaults.HellXmtIdle == true)
 			c = '.';
 		else {

src/include/fl_digi.h

@@ -236,6 +236,14 @@ extern void queue_execute_after_rx(void*);
 
 extern int rxtx_charset;
 extern void put_rx_data(int *data, int len);
+
+// Values returned by get_tx_char() to signal various conditions to the
+// modems. These values need to be negative so they don't interfere with
+// normal TX data (which is always byte-sized and positive).
+
+#define GET_TX_CHAR_NODATA -1	// no data available
+#define GET_TX_CHAR_ETX -3	// end of transmission requested
+
 extern int get_tx_char();
 extern int  get_secondary_char();
 extern void put_echo_char(unsigned int data, int style = FTextBase::XMIT);

src/mfsk/mfsk.cxx

@@ -914,9 +914,9 @@ int mfsk::tx_process()
 				startpic = false;
 				txstate = TX_STATE_PICTURE_START;
 			}
-			else if ( xmtbyte == 0x03 || stopflag)
+			else if ( xmtbyte == GET_TX_CHAR_ETX || stopflag)
 				txstate = TX_STATE_FLUSH;
-			else if (xmtbyte == -1)
+			else if (xmtbyte == GET_TX_CHAR_NODATA)
 				sendidle();
 			else
 				sendchar(xmtbyte);

src/mt63/mt63.cxx

@@ -76,12 +76,12 @@ int mt63::tx_process()
     }
 
 	c = get_tx_char();
-	if (c == 0x03)  {
+	if (c == GET_TX_CHAR_ETX)  {
 		stopflag = true;
 		flush = Tx->DataInterleave;
 	}
 
-	if (c == -1 || stopflag == true) c = 0;
+	if (c == GET_TX_CHAR_NODATA || stopflag == true) c = 0;
 
 	if (stopflag) {
 		stopflag = false;

src/navtex/navtex.cxx

@@ -1586,7 +1586,7 @@ public:
 		for(;;)
 		{
 			int c = get_tx_char();
-			if( c == -1 ) {
+			if( c == GET_TX_CHAR_NODATA ) {
 				break ;
 			}
 			msg.push_back( c );

src/olivia/olivia.cxx

@@ -161,12 +161,12 @@ int olivia::tx_process()
 // whatever there is.
 
 	if (stopflag || (Tx->GetReadReady() < Tx->BitsPerSymbol)) {
-		if (!stopflag && (c = get_tx_char()) == 0x03)
+		if (!stopflag && (c = get_tx_char()) == GET_TX_CHAR_ETX)
 			stopflag = true;
 		if (stopflag)
 			Tx->Stop();
 		else {
-			if (c == -1)
+			if (c == GET_TX_CHAR_NODATA)
 		                c = 0;
 			if (c > 127) {
 				if (progdefaults.olivia8bit && c <= 255) {
@@ -183,9 +183,8 @@ int olivia::tx_process()
 		}
 	}
 
-	if (c != 0 && c != 0x03) {
+	if (c > 0)
 		put_echo_char(c);
-	}
 
 	if ((len = Tx->Output(txfbuffer)) > 0)
 		ModulateXmtr(txfbuffer, len);

src/packet/pkt.cxx

@@ -2304,7 +2304,7 @@ int pkt::tx_process()
 
     // TX buffer empty
     //    if (c == 0x03 || stopflag) {
-    if (c == -1 || stopflag || tx_char_count == 0) {
+    if (c == GET_TX_CHAR_ETX || stopflag || tx_char_count == 0) {
 	if (!stopflag) {
 	    // compute FCS and add it to the frame via *tx_cbuf
 	    unsigned int fcs = computeFCS(&txbuf[0], tx_cbuf);

src/psk/psk.cxx

@@ -1081,14 +1081,14 @@ int psk::tx_process()
 
 	c = get_tx_char();
 
-	if (c == 0x03 || stopflag) {
+	if (c == GET_TX_CHAR_ETX || stopflag) {
 		tx_flush();
 		stopflag = false;
 		cwid();
 		return -1;   // we're done
 	}
 
-	if (c == -1) {
+	if (c == GET_TX_CHAR_NODATA) {
 		if (_pskr) {
 			// MFSK varicode instead of psk
 			tx_char(0);   // <NUL>

src/thor/thor.cxx

@@ -869,9 +869,9 @@ int thor::tx_process()
 		break;
 	case TX_STATE_DATA:
 		i = get_tx_char();
-		if (i == -1)
+		if (i == GET_TX_CHAR_NODATA)
 			sendsecondary();
-		else if (i == 3)
+		else if (i == GET_TX_CHAR_ETX)
 			txstate = TX_STATE_END;
 		else
 			sendchar(i, 0);

src/throb/throb.cxx

@@ -621,7 +621,7 @@ int throb::tx_process()
 	c = get_tx_char();
 
 // end of transmission
-	if (c == 0x03 || stopflag) {
+	if (c == GET_TX_CHAR_ETX || stopflag) {
 		send(idlesym);
 //		reset_syms(); //prepare RX. idle/space syms always start as 0 and 1, respectively.
 		cwid();
@@ -629,7 +629,7 @@ int throb::tx_process()
 	}
 
 // TX buffer empty
-	if (c == -1) {
+	if (c == GET_TX_CHAR_NODATA) {
 		send(idlesym);	/* send idle throbs */
 		flip_syms();
 		return 0;

src/trx/nullmodem.cxx

@@ -85,7 +85,8 @@ int NULLMODEM::rx_process(const double *buf, int len)
 
 int NULLMODEM::tx_process()
 {
-	if ( get_tx_char() == 0x03 || stopflag) {
+	MilliSleep(10);
+	if ( get_tx_char() == GET_TX_CHAR_ETX || stopflag) {
 		stopflag = false;
 		return -1;
 	}

src/wwv/wwv.cxx

@@ -202,7 +202,7 @@ int wwv::tx_process()
 	static int cycle = 4;
 	int c = get_tx_char();
 
-	if (c == 0x03 || stopflag) {
+	if (c == GET_TX_CHAR_ETX || stopflag) {
 		stopflag = false;
 		return -1;
 	}