/* digitar.h
 * Fri Jun 18 18:04:12 PDT 2010 Kevin Karplus
 */

#ifndef DIGITAR_H
#define DIGITAR_H

#define SAMPLE_RATE	(44100)
	/* sampling rate in samples/second 
	 * 44100 is the stanard sampling rate for CD recordings
	 */

#define SEMITONE	(1.05946309436)
	/* ratio of frequencies in well-tempered tuning */

/* fixed-point representation for phase (and frequency)
 * has FIXED_POINT_SHIFT bits after the binary point
 */
typedef int fixed_point;
#define FIXED_POINT_SHIFT	(8)
#define FIXED_POINT_SCALING	(1<<FIXED_POINT_SHIFT)

/* wave table with waveform of length "length" <= alloc_length
 * table has alloc_length signed short integers in it, range -32768..32767
 */
struct wavetable
{   short int *table;
    int length;
    int alloc_length;
    int sum_table;	/* sum of first length entries of table */
    
    fixed_point phase;	/* phase is in range [0,length) 
    			 * (as fixed-point number)
			 */
};

/* return a pointer to a newly allocated table of the specified size */
struct wavetable* alloc_table(int max_length);

/* free_table(&table) frees the table and sets table=NULL */
void free_table(struct wavetable** tab);

/* replace wav->table[i] by x, updating wav->sum_table 
 * returns x
 */
short int  update_table(struct wavetable *wav, int i, short int x);


/* Fill wav with +-amplitude  (in range 0..32767)
 * then decay for decay_passes full passes
 */
void pluck(struct wavetable *wav, 
	int amplitude, 
	int decay_passes);

/* play num_samples long note at frequency f_Hz
 * into array out, using wavetable  wav
 * Decay rate is given in decays/sample (0 <= decay_rate )
 *
 *    returns where out pointer would have to be for next note.
 */
short int* decay_note(struct wavetable*wav, 
	float f_Hz, 
	float decay_rate, 
	int num_samples, 
	short int *out);

/* play num_samples long note at frequency f_Hz
 * into array out, using wavetable  wav
 * Decay rate is given in decays/sample (0 <= decay_rate )
 *
 * probability of bow slipping in (delta_v/v)^2/force
 *	(clipped at 1, of course)
 * bow_velocity should be fairly small (100? 1000?)
 * bow_force should be fairly small (10.?)
 */
void bow_note(struct wavetable*wav,
	float f_Hz,
	float decay_rate,
	float bow_force,
	int bow_velocity,
	int num_samples,
	short int **out_p);


#endif