#include <u.h>
#include <libc.h>
#include <thread.h>
#include "abuf.h"
#include "guic.h"

Abuf ain, aout;

enum{
	Cutoff,
	Reso,
};

char *keywords[] = {
	"cutoff",
	"reso",
	0
};

void
threadmain(int argc, char *argv[])
{
	double r, c;
	double y2, y1, y0, x0;
	Event ev;

	if(argc < 2)
		sysfatal("usage: twopole gui");
		
	guistart(argv[1]);
	
	ainit(&ain, 0);
	ainit(&aout, 1);
	
	c = 0.1;
	r = 0.98;
	y1 = y2 = 0;
	
	while(agetd(&ain, &x0) == 1){
		while(nbrecv(guichan, &ev) == 1) switch(ev.k){
		case Cutoff:
			c = ev.n / 127.0;
			break;
		case Reso:
			r = ev.n / 128.0;
			break;
		}
		y0 = c * x0 + (1 + r - c) * y1 - r * y2;
		if(y0 > 1)
			y0 = 1;
		if(y0 < -1)
			y0 = -1;
		aputd(&aout, y0);
		y2 = y1;
		y1 = y0;
	}
}