seq_oss_misc.c

Archos AVX Linux Sound driver source code

/*----------------------------------------------------------------
 * miscellaneous functions
 *----------------------------------------------------------------*/

unsigned short snd_seq_oss_semitone_tuning[24] = 
{
/*   0 */ 10000, 10595, 11225, 11892, 12599, 13348, 14142, 14983, 
/*   8 */ 15874, 16818, 17818, 18877, 20000, 21189, 22449, 23784, 
/*  16 */ 25198, 26697, 28284, 29966, 31748, 33636, 35636, 37755
};

unsigned short snd_seq_oss_cent_tuning[100] =
{
/*   0 */ 10000, 10006, 10012, 10017, 10023, 10029, 10035, 10041, 
/*   8 */ 10046, 10052, 10058, 10064, 10070, 10075, 10081, 10087, 
/*  16 */ 10093, 10099, 10105, 10110, 10116, 10122, 10128, 10134, 
/*  24 */ 10140, 10145, 10151, 10157, 10163, 10169, 10175, 10181, 
/*  32 */ 10187, 10192, 10198, 10204, 10210, 10216, 10222, 10228, 
/*  40 */ 10234, 10240, 10246, 10251, 10257, 10263, 10269, 10275, 
/*  48 */ 10281, 10287, 10293, 10299, 10305, 10311, 10317, 10323, 
/*  56 */ 10329, 10335, 10341, 10347, 10353, 10359, 10365, 10371, 
/*  64 */ 10377, 10383, 10389, 10395, 10401, 10407, 10413, 10419, 
/*  72 */ 10425, 10431, 10437, 10443, 10449, 10455, 10461, 10467, 
/*  80 */ 10473, 10479, 10485, 10491, 10497, 10503, 10509, 10515, 
/*  88 */ 10521, 10528, 10534, 10540, 10546, 10552, 10558, 10564, 
/*  96 */ 10570, 10576, 10582, 10589
};

/* convert from MIDI note to frequency */
int
snd_seq_oss_note_to_freq(int note_num)
{

	/*
	 * This routine converts a midi note to a frequency (multiplied by 1000)
	 */

	int note, octave, note_freq;
	static int notes[] = {
		261632, 277189, 293671, 311132, 329632, 349232,
		369998, 391998, 415306, 440000, 466162, 493880
	};

#define BASE_OCTAVE	5

	octave = note_num / 12;
	note = note_num % 12;

	note_freq = notes[note];

	if (octave < BASE_OCTAVE)
		note_freq >>= (BASE_OCTAVE - octave);
	else if (octave > BASE_OCTAVE)
		note_freq <<= (octave - BASE_OCTAVE);

	/*
	 * note_freq >>= 1;
	 */

	return note_freq;
}

unsigned long
snd_seq_oss_compute_finetune(unsigned long base_freq, int bend, int range, int vibrato_cents)
{
	unsigned long amount;
	int negative, semitones, cents, multiplier = 1;

	if (!bend || !range || !base_freq)
		return base_freq;

	if (range >= 8192)
		range = 8192;

	bend = bend * range / 8192;	/* Convert to cents */
	bend += vibrato_cents;

	if (!bend)
		return base_freq;

	negative = bend < 0 ? 1 : 0;

	if (bend < 0)
		bend *= -1;
	if (bend > range)
		bend = range;

	/*
	   if (bend > 2399)
	   bend = 2399;
	 */
	while (bend > 2399) {
		multiplier *= 4;
		bend -= 2400;
	}

	semitones = bend / 100;
	if (semitones > 99)
		semitones = 99;
	cents = bend % 100;

	amount = (int) (snd_seq_oss_semitone_tuning[semitones] * multiplier *
			snd_seq_oss_cent_tuning[cents]) / 10000;

	if (negative)
		return (base_freq * 10000) / amount;	/* Bend down */
	else
		return (base_freq * amount) / 10000;	/* Bend up */
}