12f8
/* rtty med HAMCOMM-interfacet */


#include <stdio.h>
#include <conio.h>
#include <dos.h>
#include <bios.h>
#include <mem.h>
#include <math.h>

extern void cmpt_init(void);
extern void cmpt_exit(void);
extern unsigned tone_freq;
unsigned old_tonefreq;
extern unsigned int timerticks;
unsigned char letter;
unsigned char c;
int smp_cntr;

#define LTRS 0x1f
#define FGRS 0x1b
#define LTRS_OFF 0
#define FGRS_OFF 32
int tab_offs = LTRS_OFF;

unsigned char b2a_tab[] =
{

  0, 'T',  13, 'O', ' ', 'H', 'N', 'M',  10, 'L', 'R', 'G', 'I', 'P', 'C',
'V', 'E', 'Z', 'D', 'B', 'S', 'Y', 'F', 'X', 'A', 'W', 'J', '*', 'U', 'Q',
'K', '*',

  0, '5',  13, '9', ' ',   0, ',', '.',  10, ')', '4',   0, '8', '0', ':',
'=', '3', '+',   0, '?',   0, '6',   0, '/', '-', '2',   7, '*', '7', '1',
'(', '*'

};

char scrbuf[4000];


unsigned fc,markfreq,spacefreq,shift;
float baud;
unsigned wait_tm;
int x_sav,y_sav;
unsigned freq_cntr,noise_cntr;

int rev;
char *nrmrevstr[2] = {"NORMAL","REVERSE"};
unsigned maxval;

main()
{
int i;

	cmpt_init();
	clrscr();

	fc=2200;
	baud=45.45;
	shift=170;
	rev=0;
	set_freqs(1);

	tone_freq=0;

	while(1) {
		maxval=(shift/2)-5;
		freq_cntr = 0;

		while(1) {
			if((tone_freq >= spacefreq-maxval) && (tone_freq <= spacefreq+maxval))
				freq_cntr++;
			else
				freq_cntr=0;

			if(freq_cntr==30) break;

			if(kbhit())
				if(process_key())
					break;
				else
					goto rdy;
		}

		wait_tm=(unsigned)(1193180l/baud);
		wait(wait_tm+(wait_tm/2));
		do_letter();

		if(kbhit())
			if(! process_key()) break;
	}
rdy:
	cmpt_exit();
}

process_key()
{
int c;

	c = getch();
	if(c==0) {
		c=getch();
		switch(c){
			case 0x30: 	set_baud();       /* Alt-B */
						break;
			case 0x1f:  set_shift();      /* Alt-S */
						break;
			case 0x2e:  set_fc();         /* Alt-C */
						break;
			case 0x13:  rev ^= 1;         /* Alt-R */
						set_freqs(1);
						break;
			case 0x14:  tune();           /* Alt-T */
						break;
			case 0x2d:  return 0;         /* Alt-X */
		}
	}
	return 1;
}


set_baud()
{
char baudstr[20];

	printf("\nEnter baud rate: ");
	gets(baudstr);
	baud = atof(baudstr);
}

set_shift()
{
char shiftstr[20];

	printf("\nEnter shift: ");
	gets(shiftstr);
	shift = atoi(shiftstr);
	set_freqs(0);
}

set_fc()
{
char fcstr[20];

	printf("\nEnter Center frequency: ");
	gets(fcstr);
	fc = atoi(fcstr);
	set_freqs(0);
}


tune()
{
 int center_x,tone_x;

	HideCur();
	cursave();
	save_scr();
	clrscr();

	center_x=fc/50;

	gotoxy(1+center_x,1);
	putch('*');

	while(1) {
		if(tone_x != center_x) {
			gotoxy(1+tone_x,1);
			putch(' ');
		}
		tone_x=tone_freq/50;
		gotoxy(1+tone_x,1);
		putch('|');
		if(tone_x == center_x){
			gotoxy(1+center_x,1);
			putch('*');
		}

		if(kbhit()){
			getch();
			break;
		}
	}
	rest_scr();
	currest();
	ShowCur(6,7);
}


do_letter()
{
int i,err;
unsigned t;

	letter = 0x00;
	err=0;

	for(i=0;i<5;i++){
		letter <<= 1;
		if((tone_freq >= markfreq-maxval) && (tone_freq <= markfreq+maxval))
			letter |= 0x01;
		else if((tone_freq >= spacefreq-maxval) && (tone_freq <= spacefreq+maxval))
			letter |= 0x00;
		else err=1;
		wait(wait_tm);
	}

	if(! err){
		switch(letter) {
			case LTRS: 	tab_offs = LTRS_OFF;
						break;
			case FGRS: 	tab_offs = FGRS_OFF;
						break;
			default:    c = b2a_tab[tab_offs+letter];
						putchar(c);
		}
	}
}

set_freqs(int with_text)
{
	switch(rev){
		case 0:	markfreq = fc+shift/2;
				spacefreq = fc-shift/2;
				break;
		case 1: markfreq = fc-shift/2;
				spacefreq = fc+shift/2;
	}
	if(with_text)
		printf("\nNrm/Rev: %s\n",nrmrevstr[rev]);
}

wait(unsigned t)
{
unsigned latch1,latch2;

	asm{
		push ax
		push dx
		mov al,00h
		out 43h,al
		in al,40h
		mov dl,al
		in al,40h
		mov dh,al
		mov latch1,dx
		pop dx
		pop ax
	}

	while(1) {
		asm{
			push ax
			push dx
			mov al,00h
			out 43h,al                /* latch current counter value */
			in al,40h
			mov dl,al
			in al,40h
			mov dh,al
			mov latch2,dx
			pop dx
			pop ax
		}
		if(latch1-latch2 >= t)
			break;
	}
}

HideCur()
{
	 asm{
		push ax
		push cx

		mov ah,01h
		mov ch,00100110b
		mov cl,00000111b
		int 10H

		pop cx
		pop ax
	 }
}

ShowCur(char start, char end)
{
	 asm{
		push ax
		push cx

		mov ah,01H
		mov ch,start
		mov cl,end
		int 10H

		pop cx
		pop ax
	 }
}

cursave()
{
	x_sav = wherex();
	y_sav = wherey();
}

currest()
{
	gotoxy(x_sav,y_sav);
}

save_scr() {
char far* p;
	p = MK_FP(0xb800,0x0000);
	_fmemcpy((char far*)scrbuf,p,4000);
}
rest_scr()
{
char far* p;

	p = MK_FP(0xb800,0x0000);
	_fmemcpy(p,(char far*)scrbuf,4000);
}
.

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