#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <termios.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <signal.h>
#include <sys/io.h>

/*	set_dac.c 
 *	
 *	Func:	set_dac.c uses the RTS and DTR pins of a serial device found at /dev/ttyS1 to 
 *			set the power levels of the DAC. 
 *			DTR is used as the clock signal SCL
 *			RTS is used as the data signal SDA
 *			Please refer to the Max521 specs page for more information on SCL, SDA.
 *
 *	Usage:	set_dac <dac number> <dac power level>
 *			<dac number> should be between 0-15 and indicate which dac to set.
 *			<dac power level> should be between 0-255 and indicate the power level to set.
 *	
 *	Author:	Wonsop Sim
 *
 *	Date:	July 28, 2004
 */

//implements a <count> microsecond delay by reading from a slow I/O port.
void delay (int count)
{
	volatile int x;
	int i;
	for(i=0; i<count; i++)
		x = inb(0x40);       // safe slow I/O port to read
}


int main (int argc, char **argv)
{
	int dac_arg;
	int	dac_adr;
	int	dac_num;
	int	pow_lvl;
	int fd;
	int flags;
	int i;
	int count = 5;

	//grab command line arguments
	dac_arg = atoi(argv[1]);
	pow_lvl = atoi(argv[2]);

	//check to make sure arguments are in the correct range
	if (dac_arg >= 0 && dac_arg < 8) {
		dac_adr = 0;
		dac_num = dac_arg;}
	else if (dac_arg >= 8 && dac_arg < 16) {
		dac_adr = 3;
		dac_num = dac_arg - 8;}
	else {
		fprintf(stderr, "DAC address must be in range 0-15\n");
		exit(1);}
	if (pow_lvl < 0 || pow_lvl > 255) {
		fprintf(stderr, "Power level must be in range 0-255\n");
		exit(1);}
	
	//add in factory set bits to the address
	dac_adr = (dac_adr * 2) + 80;

	//open the device
	if ((fd = open("/dev/ttyS1", O_RDWR | O_NDELAY)) < 0) {
		fprintf(stderr, "device not found");
		exit(1);}

	//enable I/O port controls
	iopl(3);

	//get line bits for serial port
	ioctl(fd, TIOCMGET, &flags);

	//make sure RTS and DTR lines are high
	flags &= ~TIOCM_RTS;
	flags &= ~TIOCM_DTR;
	ioctl(fd, TIOCMSET, &flags);
	delay(count);
	
	//do start condition 
	flags |= TIOCM_RTS;
	ioctl(fd, TIOCMSET, &flags);
	delay(count);
	flags |= TIOCM_DTR;
	ioctl(fd, TIOCMSET, &flags);
	delay(count);

	//do address byte
	for (i = 7; i >=0; i--) {
		if ((dac_adr >> i) & 1)
			flags &= ~TIOCM_RTS;
		else
			flags |= TIOCM_RTS;
		ioctl(fd, TIOCMSET, &flags);
		delay(count);
		flags &= ~TIOCM_DTR;
		ioctl(fd, TIOCMSET, &flags);
		delay(count);
		flags |= TIOCM_DTR;
		ioctl(fd, TIOCMSET, &flags);
		delay(count);
	}
	//acknowledge bit
	flags |= TIOCM_RTS;
	ioctl(fd, TIOCMSET, &flags);
	delay(count);
	flags &= ~TIOCM_DTR;
	ioctl(fd, TIOCMSET, &flags);
	delay(count);
	flags |= TIOCM_DTR;
	ioctl(fd, TIOCMSET, &flags);
	delay(count);

	//do command byte
	for (i = 7; i >=0; i--) {
		if ((dac_num >> i) & 1)
			flags &= ~TIOCM_RTS;
		else
			flags |= TIOCM_RTS;
		ioctl(fd, TIOCMSET, &flags);
		delay(count);
		flags &= ~TIOCM_DTR;
		ioctl(fd, TIOCMSET, &flags);
		delay(count);
		flags |= TIOCM_DTR;
		ioctl(fd, TIOCMSET, &flags);
		delay(count);
	}
	//acknowledge bit
	flags |= TIOCM_RTS;
	ioctl(fd, TIOCMSET, &flags);
	delay(count);
	flags &= ~TIOCM_DTR;
	ioctl(fd, TIOCMSET, &flags);
	delay(count);
	flags |= TIOCM_DTR;
	ioctl(fd, TIOCMSET, &flags);
	delay(count);
	
	//do output byte
	for (i = 7; i >=0; i--) {
		if ((pow_lvl >> i) & 1)
			flags &= ~TIOCM_RTS;
		else
			flags |= TIOCM_RTS;
		ioctl(fd, TIOCMSET, &flags);
		delay(count);
		flags &= ~TIOCM_DTR;
		ioctl(fd, TIOCMSET, &flags);
		delay(count);
		flags |= TIOCM_DTR;
		ioctl(fd, TIOCMSET, &flags);
		delay(count);
	}
	//acknowledge bit
	flags |= TIOCM_RTS;
	ioctl(fd, TIOCMSET, &flags);
	delay(count);
	flags &= ~TIOCM_DTR;
	ioctl(fd, TIOCMSET, &flags);
	delay(count);
	flags |= TIOCM_DTR;
	ioctl(fd, TIOCMSET, &flags);
	delay(count);

	//do stop condition
	flags &= ~TIOCM_DTR;
	ioctl(fd, TIOCMSET, &flags);
	delay(count);
	flags &= ~TIOCM_RTS;
	ioctl(fd, TIOCMSET, &flags);
	delay(count);

	close(fd);
	
	return 0;

}