/*
******************************************************************************
		       C Language Sample #3 : SAMPLE3.C

	This program will set up counter 2 to decrement from 101 hex,
	sending out a pulse when reaching zero. The value of the
	counter will be read and displayed until zero is reached. Because the
	counter is extremely fast, the program will rarely catch it at zero,
	so execution will end soon after that point is reached.

******************************************************************************
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <conio.h>
#include <dos.h>

unsigned int Address; 	/* The Base address of the watchdog board. */
unsigned int Com_Adr; 	/* The Base Address of the communications
				   segment of the board. */

/*
******************************************************************************
FUNCTION set_counter()
Purpose: This function performs the setup operations on the 8253-5 counter/
	 timer chip. Counter two will be set for two byte load/read, mode
	 zero, binary.
******************************************************************************
*/
void set_counter(void)
{
  int	control_word;

  control_word = 0xB0;		/* Set counter 2, Read/Load Least Sig Byte
				   then Most Sig Byte, Mode 0, binary count */
  outportb(Address+3,control_word); /* Write control word to the counter
				   control register. */
  outportb(Address+2,0x01);	/* Write 101 hex to counter 2
				   register. */
  delay(5);			/* Provide a brief pause between writes. */
  outportb(Address+2,0x01);	/* Write 101 hex to counter
				   2 register. */
  delay(25);
} /* End set_counter() */

/*
******************************************************************************
FUNCTION read_counter()
Purpose: This function reads the value of the counter. The value is read in
	 two bytes, least significant byte first. The function will then
	 combine the two and return that value.
******************************************************************************
*/
unsigned read_counter(void)
{
  unsigned read_back = 0, counter_value = 0;

  outportb(Address+3,0x80);	/* Counter Latching: Allows for the reading
				   of both bytes without halting the counter.*/
  read_back = inportb(Address+2);	/* Read Least Significant Byte */
  counter_value  = read_back;           /* Move low byte into storage */
  read_back = inportb(Address+2);	/* Read Most Significant Byte */
  counter_value += read_back << 8;	/* Shift high byte and store */
  return(counter_value);
} /* End read_counter() */

/*
******************************************************************************
Function AskForBaseAddress
Purpose:    This function allows the user to input the address of the
	    card.
******************************************************************************
*/
unsigned AskForBaseAddress(unsigned int OldOne)
{
	char msg[7];
	int NewOne = 0, Success = 0, Dummy;
	int AddrInputPosX, AddrInputPosY;

	puts("\nPlease enter the Base Address for your card (in hex)");
	printf("or press ENTER for %X.\n>", OldOne);
	AddrInputPosX = wherex(); AddrInputPosY = wherey();
	do {
      gotoxy(AddrInputPosX, AddrInputPosY);
      clreol();
      msg[0] = 5; msg[1] = 0;
      cgets(msg);
      sscanf(msg + 2, "%x", &NewOne);
      Success = 1;
      Dummy = NewOne;
		if (msg[1] == 0) {
        gotoxy(AddrInputPosX, AddrInputPosY);
        printf("%X", OldOne);
	Success = 1;
	Dummy = OldOne;
      }
	} while(!Success);
	return (Dummy);
} /* end of AskForBaseAddress */
/*
******************************************************************************
FUNCTION main()
Purpose: This function controls program flow, making calls to the other
	 functions, and prompting for user input.
******************************************************************************
*/

void main()
{
  int Dummy;
  unsigned  counter_value = 0x101 ,read_back,last_value;

  clrscr();
  puts("             SAMPLE 3.C : Use Of Counter/Timer Chip\n");
  puts("This program demonstrates how to program the 8253-5 counter/timer");
  puts("chip on the Watchdog Timer board.  If the card has the optional relay,");
  puts("the chip will send a pulse that will trip the relay.  This should");
  puts("cause two audible clicks, one for when the counter is enabled, and one");
  puts("for the pulse. There will be a delay of about five minutes between");
  printf("these occurences. A keystroke will stop the program.\n\n\n");

  gotoxy(1,10);
  puts("COM ADDRESS");
  Com_Adr = AskForBaseAddress(0x2A8);

  gotoxy(1,17);
  puts("WATCHDOG ADDRESS");
  Address = AskForBaseAddress(0x350);

  clrscr();
  printf("\n\n\nBoard Configuration:\n\n");
  printf(" -- Base Address is %X hex.\n",Com_Adr);
  printf(" -- Watchdog Address is %X hex.\n",Address);
  printf(" -- All remaining jumper settings are irrelevant.\n\n\n");
  printf("Press a key to continue");
  getch();
  clrscr();
  outportb(Com_Adr+4, 4);	/* The output to the relay is
                                   controlled by a bit in the UART.
                                   Setting this bit opens the line
                                   to the relay and causes the first
                                   click. Send new value to the UART. */
  set_counter();                /* Set counter and start the countdown. */
  do
    {
    last_value = counter_value;
    counter_value = read_counter();
    gotoxy(1,1);
    printf("Value read from counter: %u\n",counter_value);
    }
  while (!kbhit() && (counter_value < last_value));
  if (kbhit())
    getch();				/* Strip keystroke from buffer. */

}