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

double
miditofreq(int note)
{
	return 440.0 * pow(2, (note - 69.0) / 12);
}

double
miditophase(int note)
{
	return miditofreq(note) / SRATE;
}

double
voltomul(int level)
{
	double x = level/127.0;
	return pow(2, 2*(x-1))*x;
}

void
ainit(Abuf *ab, int fd)
{
	ab->p = 0;
	ab->fd = fd;
}

void
aflush(Abuf *ab)
{
	write(ab->fd, ab->buf, ab->p);
	ab->p = 0;
}

void
aput(Abuf *ab, sample n)
{
	int p;
	uchar *s;
	p = ab->p;
	s = ab->buf + p;
	s[0] = n;
	s[1] = n >> 8;
	s[2] = n;
	s[3] = n >> 8;
	p += 4;
	if(p == ABUFSZ){
		write(ab->fd, ab->buf, p);
		p = 0;
	}
	ab->p = p;
}

int
aget(Abuf *ab, sample *n)
{
	int p;
	uchar *s;
	
	p = ab->p;
	if(p == 0){
		p = readn(ab->fd, ab->buf, ABUFSZ);
		if(p <= 0)
			return p;
		if(p % 4 != 0)
			return 0;
	}
	s = &ab->buf[ABUFSZ - p];
	*n = s[0] + 256 * s[1];
	ab->p = p - 4;
	return 1;
}

void
aputd(Abuf *ab, double n)
{
	aput(ab, (int)(n * SMAX));
}

int
agetd(Abuf *ab, double *n)
{
	int r;
	sample s;
	r = aget(ab, &s);
	*n = s / SMAX;
	return r;
}