#ifndef MPG123_WAVES_H

#define MPG123_WAVES_H

/*

waves: some oscillators, for fun

copyright 2017 by the mpg123 project, license: LGPL 2.1

This originates from Thomas' DerMixD, but the idea is probably generic

enough: Construct a buffer containing a lookup table that covers some

periods (for fractinal relations between sampling frequency and generated

wave frequency).

For added fun, this not only has a single oscillator, but combines any

number of them (multiplicative).

Storage format is interleaved PCM samples.

*/

#include "config.h"

#include "compat.h"

#include "fmt123.h"

struct wave_table

{

void *buf; /* period buffer */

struct mpg123_fmt fmt;

size_t samples; /* samples (PCM frames) in period buffer */

size_t offset; /* offset in buffer for extraction helper */

size_t count; /* number of combined waves */

double *freq; /* actual wave frequency list */

};

extern const char *wave_pattern_default;

extern const char *wave_pattern_list;

/* Depending on your selection of frequencies, a very large table */

/* might be required to cover them properly. You are required to provide */

/* a limit for the table size, prompting adjustment on the frequencies */

/* to make things fit. The limit is not strict, it can be overstepped by */

/* about one period of one of the configured waveforms. */

struct wave_table* wave_table_new(

long rate, int channels, int encoding /* desired output format */

, size_t count, double *freq /* required: number and frequencies of waves */

, const char** pattern /* optional: wave pattern list */

, double *phase /* optional: phase shift list */

, size_t size_limit /* non-strict upper limit for table size */

);

/* The destructor. Returns NULL, always. */

void* wave_table_del(struct wave_table* handle);

/* Extract the desired amount of samples (PCM frames). */

/* Returns said amount of samples, too, if successful. */

size_t wave_table_extract( struct wave_table *handle

, void *dest, size_t samples );

#endif