/*
 * This program emulates a dump terminal with file transfer support using
 * CompuServe's B-Protocol.  This program is just a sample of how to interface
 * the BP module (BP.C) with the rest of the terminal emulator.
 */

#include "\lc\stdio.h"

extern int Transfer_File();	/* Transfer a file using the "B" protocol */
extern int Read_Keyboard();	/* Get a "raw" character from the keyboard */
extern Init_Comm();		/* Initialize the comm port */
extern int Read_Modem();	/* Read a character from the comm port */
extern int Write_Modem();	/* Send a character to the comm port */
extern Term_Comm();

#define True  1
#define False  0
#define Exit_Key  0x010F
#define Is_Function_Key(C)  ((C) & 0x0100)

#define ENQ  0x05
#define DLE  0x10
#define ESC  0x1B

static char VIDTEX_Response[] = "#IB1,PB,DT\015";

static int
    Old_Break_State,
    I,
    Ch,				/* 16-bit "raw" character. If > 127 than we
    				   have a function key. */
    Want_7_Bit,
    ESC_Seq_State;		/* Escape sequence state variable */


int Wants_To_Abort()
{
    return Read_Keyboard() == ESC;
}

main()
{
    char *cp;

    Want_7_Bit = True;
    ESC_Seq_State = 0;
    Old_Break_State = Get_Break();
    Set_Break(0);
    Init_Comm();
    puts("[ Terminal Mode ]");
    Ch = Read_Keyboard();

    while (Ch != Exit_Key)
	{
	if (Ch > 0)
	    {
	    if (Is_Function_Key(Ch))
		{
		/* Here to process any local function keys. This sample
		 * program is real dumb. The only function key is the EXIT
		 * key (Alt-X).
		 */
		}
	    else
		Write_Modem(Ch & 0x7F);
	    }

	if ((Ch = Read_Modem()) >= 0)
	    {
	    if (Want_7_Bit) Ch &= 0x7F;

	    switch (ESC_Seq_State)
		{
		case 0:
		    switch (Ch)
			{
			case ESC:
			    ESC_Seq_State = 1;
			    break;

			case ENQ:
			    /* Enquiry -- send ACK for packet 0 */

			    Write_Modem(DLE);
			    Write_Modem('0');
			    break;

			case DLE:
			    ESC_Seq_State = 2;
			    break;

			default:
			    Put_Char(Ch);
			}

		    break;

		case 1:
		    /* ESC -- process any escape sequences here */

		    switch (Ch)
			{
			case 'I':
			    /* Reply to the VIDTEX "ESC I" identify sequence */
			    cp = VIDTEX_Response;
			    while (*cp != 0) Put_Char(*cp++);
			    ESC_Seq_State = 0;
			    break;

			default:
			    Put_Char(ESC);
			    Put_Char(Ch);
			    ESC_Seq_State = 0;
			}

		    break;

		case 2:
		    /* DLE */

		    if (Ch == 'B')
			{
			/* Start of "B" protocol packet. Go into protocol
			 * mode and transfer the file as requested.
			 */

			if (!Transfer_File()) puts("Transfer failed!");
			}
		    else
			{
			Put_Char(DLE);
			Put_Char(Ch);
			}

		    ESC_Seq_State = 0;
		}
	    }

	Ch = Read_Keyboard();
	}

    Term_Comm();
    Set_Break(Old_Break_State);
}