/* -------------------------------------------
 * Rountines to interface between internal and
 * external notions of what the settings are
 * --------------------------------------------
 */


# include "su1hdr.h"

/* Micro Decision specific offsets
 * -------------------------------
 */
# define HIGHBYTE	0xFF00
# define BIOS		0xF200
# define RAMDATY	0x42

/* offsets from ramdaty
 * --------------------
 */
# define CBAUDOFF	(-6)
# define PBAUDOFF	(-5)
# define OLDDFLAG	(11)
# define NEWDFLAG	(0x12)

/* bits
 * ----
 */
# define HARDBIT	(1 << 4)
# define CENTBIT	(1 << 5)

/* revision numbers
 * ----------------
 */
# define MINIMUM	0x20	/* minimum acceptable rev. level */
# define MD11 		0x40
# define REVISION	(bios [0x3f]) /* REV byte */


/* # define SET		0x52
 */


static unsigned dflag = 0;

/* block attempts to use with old versions of the system
 * -----------------------------------------------------
 */

sysinit ()
	{
	findsys ();
	version ();
	}

/* determine the memory address of the BIOS in memory
 * --------------------------------------------------
 */

findsys ()
	{
	unsigned *i;

	i = 1;
	bios = *i & HIGHBYTE;

	i = bios + RAMDATY;
	ramdaty = *i;
	}

version ()
	{
	if (REVISION < MINIMUM)
		fatal ("Old version of CP/M\r\n$");

	if (REVISION >= MD11)
		dflag = NEWDFLAG;
	else
		dflag = OLDDFLAG;
	}

/* read the settings (always from the currently running bios)
 * ----------------------------------------------------------
 */

readsettings ()
	{
	cbaud = ramdaty [CBAUDOFF] % NBAUD;
	pbaud = ramdaty [PBAUDOFF] % NBAUD;

	if (ramdaty [dflag] & CENTBIT)
		ptype = CENTRONICS;
	else
		ptype = SERIAL;

	if (ramdaty [dflag] & HARDBIT)
		protocol = HARDHAND;
	else
		protocol = XONXOFF;
	}

writesettings (a)
	unsigned char *a;
	{
	a [CBAUDOFF] = cbaud;
	a [PBAUDOFF] = pbaud;

	a [dflag] &= ~(CENTBIT | HARDBIT);
	if (protocol == HARDHAND)
		a [dflag] |= HARDBIT;

	if (ptype == CENTRONICS)
		a [dflag] |= CENTBIT;
	}

softset ()
	{
	writesettings (ramdaty);
	bioset ();	/* call the bios to have appropriate settings made */
	}

hardset ()
	{
	biosread ();
	writesettings (ramdaty + (unsigned) biosbuf - (unsigned) bios);
	bioswrite ();
	}

/* Block I/O routines for the Micro Decision
 * -----------------------------------------
 */

static spt = 0;

# define DRIVE0 0
# define NBIOSREC 20
# define BIOSFIRST 53
# define CSELECT 14
# define CGETPARM 31


biosread ()
	{
	static char *p;
	static s, n;

	spt = findspt ();
	p = biosbuf;
	s = BIOSFIRST;
	for (n = 0; n < NBIOSREC; n++, p += RECSIZE, s++)
		if (lio (READ, p, s))
			fatal ("Can't read bios\n$");
	}

bioswrite ()
	{
	static char *p;
	static s, n;

	p = biosbuf;
	s = BIOSFIRST;
	for (n = 0; n < NBIOSREC; n++, p += RECSIZE, s++)
		if (lio (WRITE, p, s, n == NBIOSREC - 1))
			fatal ("Can't write bios\n$");
	}

lio (op, addr, sector, last)
	char *addr;
	{
	int t, s;

	sector--;
	t = sector / spt;
	s = sector % spt + 1;
	return sio (op, addr, t, s, last);
	}

sio (op, addr, track, sector, last)
	{
	static char selected [5] = {NO};

	callbios (SETDRV, DRIVE0, selected[DRIVE0]);
	selected[DRIVE0] = YES;
	callbios (SETTRK, track,  0);
	callbios (SETSEC, sector, 0);
	callbios (SETDMA, addr,   0);
	if (op == READ)
		return callbios (BIORED, 0, 0);
	else
		return callbios (BIOWRT, last, 0);
	}

fatal (a)
	char *a;
	{
	prs (a);
	exit (NO);
	}