/* Sean Bradly - 2009 */
#include <stdio.h>
#include <stdlib.h> 
#include <time.h>   /* for nanosleep */
#include <curses.h> /* for nonblocking getch */
#include <sys/io.h> /* for ioperm and outb */

/* Check with /proc/ioports to make sure this io-mapping is correct */
#define LPT0 0x03bc

/* Modify depending on what pins you attached LEDs to */
#define RED   ( 1 << 0 )
#define GREEN ( 1 << 1 )
#define BLUE  ( 1 << 2 )

/* Simple use toggle macros */
#define ON(LED)  (lpt0_shadow |=  LED)
#define OFF(LED) (lpt0_shadow &= ~LED)

/* One-liner to flush local copy of port to the wire */
#define OUTPUT outb(lpt0_shadow,LPT0)

/* char to simulate led ' '=off or [.,oO]=on w/ brightness */ 
#define FAKELED(val,color) (lpt0_shadow & color)?((val>192)?'O':(val>128)?'o':(val>64)?',':'.'):' '

/* keep a copy of the port status to prevent clobbering pins unintentionally */
static unsigned char lpt0_shadow = 0;

/* Ncurses foo */
WINDOW *window;
int handle_keys(unsigned char *, unsigned char *, unsigned char *, unsigned int *);

int 
main(int argc, char *argv[])
{
	unsigned int finished = 0;
	
	/* Timer values */
	struct timespec tm = {0,0};
	int freq=1;

	/* Contains current RGB values (0..255) */
	unsigned char r,g,b;
	unsigned char r_ctr,g_ctr,b_ctr;
	r=g=b=r_ctr=g_ctr=b_ctr=0;

	/* Get permission for raw IO */
	if(ioperm(LPT0,3,1))
	{
		fprintf(stderr,"Failed to get raw IO permissions (are you root?)\n");
		exit(-1);
	}

	/* set all output pins to 0 */
	OFF(RED); OFF(GREEN); OFF(BLUE);
	OUTPUT; 

	/* Initialize ncurses for nonblocking key polling w/o echo */
	window = initscr();
	cbreak();
	noecho();
	nodelay(window,1);
	keypad(window,1);

	/* Loop until done */
	while(!finished)
	{
		/* configure output bits */
		(r_ctr<r) ? ON(RED)   : OFF(RED);
		(g_ctr<g) ? ON(GREEN) : OFF(GREEN);
		(b_ctr<b) ? ON(BLUE)  : OFF(BLUE);
		/* send bits to the physical pins */
		OUTPUT;
		/* delay (1bil nanosec/sec)/(256 duty cycle steps)/(hZ)*/
		tm.tv_nsec = (long)(1000000000/(double)freq/256.0); 
		nanosleep(&tm,NULL);
		/* update counters */
		r_ctr++; g_ctr++; b_ctr++;
		/* use ncurses to check keypresses */
		finished = handle_keys(&r,&g,&b,&freq);
	} 

	/* set all pins to 0 to clean up */
	OFF(RED); OFF(GREEN); OFF(BLUE);
	OUTPUT; 
	
	/* release the port (might not be needed) */
	ioperm(LPT0,3,0); 

	/* cleanup nurses */
	endwin();

	return 0;
}

int 
handle_keys(unsigned char *r, unsigned char *g, unsigned char *b, unsigned int *freq)
{
	char status[128];
	int c;
	
	/* Dump some status info */
	snprintf(status,128,"RGB:#%02hhx%02hhx%02hhx FREQ:%dHz\n",*r,*g,*b,*freq);
	mvaddstr(0,0,status);
	snprintf(status,128,"(%c)(%c)(%c)",FAKELED(*r,RED),FAKELED(*g,GREEN),FAKELED(*b,BLUE));
	mvaddstr(1,0,status);

	/* Handle each key (backspace exits) */
	if((c=getch()) != ERR)
	{
		switch(c)
		{
		case 'q': *r-=1; break;
		case 'w': *r+=1; break;
		case 'a': *g-=1; break;
		case 's': *g+=1; break;
		case 'z': *b-=1; break;
		case 'x': *b+=1; break;
		case KEY_UP: *freq+=1; break;
		case KEY_DOWN: (*freq>1)?*freq-=1:(void)0; break;
		case KEY_BACKSPACE: return 1;
		}
	}
	
	return 0;
}