/*
 * modem i/o for dos.  This assumes you're gonna have a fossil driver
 * (from FIDO) of some sort or another and it will fail if it can't
 * find one
 */
#include <stdio.h>
#include <fcntl.h>
#include <time.h>
#include <dos.h>

#include "ttyio.h"

extern int Debug;

/* statics for conversing with the local fossil driver
 */
static int comport;
static union REGS regs;

#define FOSSIL	0x14
#define FOSSIL_FLAG 0x1954

#define TSPEED	0x00
#define	TWRITE	0x01
#define	TREAD	0x02
#define TSTAT	0x03
#define TOPEN	0x04
#define TCLOSE	0x05
#define	TDTR	0x06
#define	TFLUSH	0x0a
#define	TFLOW	0x0f
#define	TBREAK	0x1a
    
/* variables used to track carrier and make sure we don't spend too
 * much time checking for it
 */
static time_t _cd_stale;		/* when we need to check cd again */
static char _cd_checked;		/* has cd been checked? */
static char _cd_state=0;		/* what's cd now? */


/*
 * ttyopen() attaches ourself to a modem port
 */
int
ttyopen(dev, flow)
char *dev;
int flow;
{
    _cd_checked = 0;
    comport = dev[strlen(dev)-1]-'1';
    /* perform fossil init
     */
    regs.h.ah = TOPEN;
    regs.x.bx = 0;
    regs.x.cx = 0;
    regs.x.dx = comport;
    int86(FOSSIL, &regs, &regs);

    if (regs.x.ax == FOSSIL_FLAG) {
	/* we can either do rts/cts flow control or none at
	 * all
	 */
	if (flow == TTYF_RTSCTS) {
	    regs.h.ah = TFLOW;
	    regs.h.al = 0xf2;
	    regs.x.dx = comport;
	    int86(FOSSIL, &regs, &regs);
	}

	return 1;
    }
    return 0;
} /* ttyopen() */


/*
 * ttyclose() detaches ourself from a modem port and restores it to
 * the state it was in before we started hacking on it
 */
void
ttyclose()
{
    disable();

    regs.h.ah = TCLOSE;
    regs.x.dx = comport;
    int86(FOSSIL, &regs, &regs);
} /* ttyclose() */


/*
 * ttystat() tells us if there are characters waiting on input
 */
int
ttystat()
{
    regs.h.ah = TSTAT;
    regs.x.dx = comport;
    int86(FOSSIL, &regs, &regs);
    _cd_stale = clock() + (long)CLK_TCK;
    _cd_state = (regs.h.al & 0x80);
    _cd_checked = 1;

    return (regs.h.ah & 0x01);
} /* ttystat */


/*
 * dobreak() set or clear a break condition
 */
void
dobreak(setit)
int setit;
{
    regs.h.ah = TBREAK;
    regs.x.dx = comport;
    regs.h.al = setit ? 1 : 0;
    int86(FOSSIL, &regs, &regs);
} /* dobreak */


/*
 * ttyspeed() set tty speed
 */
int
ttyspeed(speed)
long speed;
{
    static unsigned long values[] = {
	38400L, 0043,
	19200L, 0003,
	9600L,  0343,
	4800L,  0303,
	2400L,  0243,
	1200L,  0203,
	600L,   0143,
	300L,   0103,
	0
    };
    register i;

    for (i=0; values[i] != 0; i+=2)
	if (values[i] == speed) {
	    regs.h.ah = TSPEED;
	    regs.x.dx = comport;
	    regs.h.al = (int)values[i+1];
	    int86(FOSSIL, &regs, &regs);
	    return 1;
	}
    return 0;
}


/*
 * carrier() - detects carrier
 */
int
carrier()
{
    register time_t now = clock();
    if (_cd_checked == 0 || now > _cd_stale) {
	regs.h.ah = TSTAT;
	regs.x.dx = comport;
	int86(FOSSIL, &regs, &regs);
	_cd_stale = clock()+(long)CLK_TCK;
	_cd_state = (regs.h.al & 0x80);
	_cd_checked = 1;
    }
    return _cd_state;
} /* carrier */


/*
 * disable the modem
 */
void
disable()
{
    regs.h.ah = TDTR;
    regs.h.al = 0;
    regs.x.dx = comport;
    int86(FOSSIL, &regs, &regs);
} /* disable */


/*
 * enable the modem
 */
void
enable()
{
    regs.h.ah = TDTR;
    regs.h.al = 1;
    regs.x.dx = comport;
    int86(FOSSIL, &regs, &regs);
} /* enable */


/*
 * flush() the modem input buffer
 */
void
flush()
{
    regs.h.ah = TFLUSH;
    regs.x.dx = comport;
    int86(FOSSIL, &regs, &regs);
} /* flush */


/*
 * receive() a character from the modem, timing out after a while
 */
int
receive(timeout)
int timeout;
{
    time_t end;

    end = clock() + ((long)timeout*(long)CLK_TCK);

    while (clock() < end)
	if (ttystat())
	    return ttyin();
    
    return -1;
} /* receive */


/*
 * ttyin() gets a character from the modem
 */
int
ttyin()
{
    regs.h.ah = TREAD;
    regs.x.dx = comport;
    int86(FOSSIL, &regs, &regs);
    return 0xff & (regs.h.al);
} /* ttyin */


/*
 * slowputs() writes a string to modem s*l*o*w*l*y
 */
void
slowputs(s)
register char *s;
{
    register long delay;

    while (*s) {
	if (*s & 0200) {	/* anything > 127 causes delay */
	    delay = (0xff & *++s);
	    nap(delay * 100L);
	    if (Debug > 1)
		fprintf(stderr, "{%ld}", delay);
	}
	else {
	    if (Debug > 1)
		putc((*s == '\r') ? '\n' : (*s), stderr);
	    nap(80L);
	    ttyout(*s);
	}
	++s;
    }
} /* slowputs */


/*
 * ttyout() writes a single character to the modem
 */
void
ttyout(c)
char c;
{
    regs.h.ah = TWRITE;
    regs.h.al = c;
    regs.x.dx = comport;
    int86(FOSSIL, &regs, &regs);
    _cd_checked = 1;
    _cd_stale = clock() + (long)CLK_TCK;
    _cd_state = (regs.h.al & 0x80);
} /* ttyout */


/*
 * ttywrite() writes a string to the modem as fast as possible
 */
void
ttywrite(bfr, size)
register char *bfr;
register size;
{
    while (size-- > 0)
	ttyout(*bfr++);
} /* ttywrite */