/* Special Raw console I/O for BDS C	G. Banks 7 Aug 1982

 *       for the Big-Board 

 *

 * Provides a reasonably flexible, device-independent interface:

 *

 *	ch = getchar()		Read a character

 *

 *	putchar(ch)		write a character

 *

 *	kbhit()			true iff input character waiting

 *

 *	old = TTYMode(m)	Sets tty mode bits to m, returning old

 *				 value.  Mode bits:

 *		1	Echo mode: chars echoed as read.

 *		2	Quit: ^C causes an exit.

 *		4	Flow: ^S, ^Q flow control.

 *		8	Strip: input characters stripped to 7 bits.

 *		16	Expand: expand \n, \t on output.

 *

 * Hence for REALLY raw I/O, do TTYMode(0).

 *

 * NOTE: Program using CIO.C are NOT PORTABLE to systems lacking a C compiler!

 *	 If you really must use CIO, then compile this once (to get CIO.CRL)

 *	 and link your programs by saying:

 *

 *		A>clink main <other CRL files> DEFF CIO <cr>

 *

 */



#include "a:bdscio.h"	



/* Device-specific definitions...	   Input status flag:		*/

#define	ISTAT	(bios(2,0)) /* use the bios input status function */

					/* character output status:	*/

#define	OSTAT	(1) /* since the Big-Board does its own I/O, it's always ready! */



/* Internal static definitions.						*/

#define	Freeze	(static[1])		/* true if output frozen (^S) */

#define	Pending	(static[2])		/* true if input char waiting */

#define	PendCh	(static[3])		/* the pending input char     */

#define	Mode	(static[4])		/* input mode bits:	     */

#define	M_echo	1			/* echo mode bit		*/

#define	M_quit	2			/* ^C (quit) mode bit		*/

#define	M_flow	4			/* ^S/^Q flow control		*/

#define	M_strip	8			/* strip to 7-bits		*/

#define	M_expan	16			/* Expand \n on output.		*/



#define	QuitC	(static[5])





putchar(c) {  rawio(1, c); }



getchar() { return rawio(2); }



kbhit() { return rawio(3); }



TTYMode(mode) { return rawio(4, mode); } /* set mode bits, returns prev. */



rawio(key, arg)

 {	char ch, *static, mode;

	static = "Nonsense!";



	if (*static == 'N')		/* Initialization ...	*/

	 { *static = Freeze = Pending = 0;

	   Mode = M_echo | M_quit | M_flow | M_strip | M_expan;

	   QuitC = 3; }



Again:	if (ISTAT)		/* check for input pending.	*/

	 { ch = bios(3,0); /* use bios to get input! */

	   if ((mode=Mode) & M_strip) ch &= 0x7F;

	   if ((mode & M_quit) && (ch == QuitC)) exit();

	   else if (mode & M_flow)

		{ if (ch == ('S'-64)) { Freeze=1; goto brk; }

		  if (ch == ('Q'-64)) { Freeze=0; goto brk; }}

	   if (!Pending)

		{ Pending = 1;

		  PendCh = ch;

		  if (mode & M_echo) bios(4, ch); }}



brk:	switch(key)

	 { case 0:	return;

	   case 1:	if (Freeze || !OSTAT) goto Again;  /* putchar(arg) */

			bios(4, arg);

			if ((arg == '\n') && (Mode & M_expan))

				putchar('\r');

			return arg;

	   case 2:	if (!Pending) goto Again;

			Pending = 0; return PendCh;

	   case 3:	return Pending;

	   case 4:	mode = Mode; Mode = arg;

			if (!(arg & M_flow)) Freeze = 0;

			return mode;

	   default:	return;

	 }

 }