#include <stdio.h>
#include <math.h>

#include "telephone.h"

int writesample(FILE *stream, long sample)
{
	int i;
	for (i = 0; i < SAMPLEDEPTH; i += 8)
		if (putc((sample>>i)&0xFF, stream) == EOF)
			return EOF;
	
	return 0;
}

int add_silence(FILE *stream, float length)
{
	size_t i;
	
	length *= SAMPLERATE;
	
	for (i = 0; i < length; ++i)
		writesample(stream, 0);
	
	return 0;
}

int add_dtmf(FILE *stream, float f1, float f2, float length)
{
	float angle1, angle2;
	size_t i;
	
	length *= SAMPLERATE;
	
	for (i = 0; i < length; ++i) {
		angle1 = 2.*M_PI*f1*i/SAMPLERATE;
		angle2 = 2.*M_PI*f2*i/SAMPLERATE;
		writesample(stream,
		  (long)floor((SAMPLERANGE>>2)*sinf(angle1)
		  + (SAMPLERANGE>>2)*sinf(angle2)));
	}
	
	return 0;
}

/* output a sine wave starting at phase 'start' ((0,1]) and return end phase */
/* starting phase is for maintaining phase */
float add_sine(FILE *stream, float freq, float length, float phase)
{
	float time = 0., unused;
	size_t i;
	
	length *= SAMPLERATE;
	
	for (i = 0; time = phase+(float)i*freq/SAMPLERATE, i < length; ++i)
		writesample(stream,
		  (long)floor((SAMPLERANGE>>1)*sinf(2.*M_PI*time)));
	
	return modff(time, &unused);
}