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/* MTERM.C - Minimal example PC terminal program.
Released to public domain by author, David Harmon, June 1992.
Intended for use with a FOSSIL driver, but will run with BIOS alone.
I expect you'll want to add something for practical purposes. ;-)
*/
#include <stdio.h>
#include <stdlib.h>
#include <conio.h> /* kbhit(), getch(), putch(), etc. */
#include <dos.h> /* int86(), etc. */
#ifdef __ZTC__
#define cputs(s) fputs((s),stderr)
#endif
int port = 0; /* 0 = COM1:, 1 = COM2: etc. */
int local_echo = 0;
int cr_add_lf = 0;
int exiting = 0;
int init_comm(int flags)
{
union REGS regs;
regs.h.ah = 0x04; /* initialize driver (port) */
regs.x.bx = 0x4f50;
regs.x.dx = port;
int86( 0x14, ®s, ®s);
regs.h.ah = 0x00; /* set baud rate * port attrs */
regs.h.al = (unsigned char)flags;
regs.x.dx = port;
int86( 0x14, ®s, ®s);
return regs.h.ah;
}
void send_char(char ch)
{
union REGS regs;
regs.h.ah = 0x01; /* Send char (wait until ready)*/
regs.h.al = ch;
regs.x.dx = port;
int86( 0x14, ®s, ®s);
}
int input_ready(void)
{
union REGS regs;
regs.h.ah = 0x03; /* Get port status */
regs.x.dx = port;
int86( 0x14, ®s, ®s);
return ((regs.h.ah & 0x01) != 0); /* input ready */
}
int get_char(void)
{
union REGS regs;
regs.h.ah = 0x02; /* receive char (wait if necessary)*/
regs.x.dx = port;
int86( 0x14, ®s, ®s);
return regs.h.al;
}
void deinit_comm(void)
{
union REGS regs;
regs.h.ah = 0x05; /* deinitialize port (pseudo close) */
regs.h.al = 0x00; /* (lower DTR) */
regs.x.dx = port;
int86( 0x14, ®s, ®s);
}
void main(void)
{
int ch;
init_comm(0xE3); /* hard coded 0xB3 = 2400,N,8,1 */
cputs("MTERM ready! Press F1 to exit.\r\n");
while (!exiting)
{
if (kbhit()) /* key was hit */
{
ch = getch(); /* Regular ASCII keys are returned as the
ASCII code; function keys, arrows, etc.
as zero followed by a special code
(on next getch.) */
if (ch != 0)
{
send_char((char)ch); /* to com port */
if (local_echo)
{
putch(ch); /* to screen */
/* add LF to CR? */
if (cr_add_lf && ch == '\r')
putch('\n');
}
}
else
{
ch = getch(); /* get the special key code */
switch (ch)
{
case 0x3B: /* F1 */
exiting = 1; /* quit now */
break;
case 0x3C: /* F2 */
local_echo = !local_echo; /* toggle echo */
break;
case 0x3D: /* F3 */
cr_add_lf = !cr_add_lf; /* toggle LF */
break;
}
}
} /* end if kbhit */
if (input_ready()) /* com port */
{
ch = get_char();
putch(ch);
if (cr_add_lf && ch == '\r') /* add LF to CR? */
putch('\n');
}
} /* end while not exiting */
deinit_comm();
}
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