path: root/sound/drivers/opl3/opl3_midi.c

/*
 *  Copyright (c) by Uros Bizjak <uros@kss-loka.si>
 *
 *  Midi synth routines for OPL2/OPL3/OPL4 FM
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

#undef DEBUG_ALLOC
#undef DEBUG_MIDI

#include "opl3_voice.h"
#include <sound/asoundef.h>

extern char snd_opl3_regmap[MAX_OPL2_VOICES][4];

extern int use_internal_drums;

/*
 * The next table looks magical, but it certainly is not. Its values have
 * been calculated as table[i]=8*log(i/64)/log(2) with an obvious exception
 * for i=0. This log-table converts a linear volume-scaling (0..127) to a
 * logarithmic scaling as present in the FM-synthesizer chips. so :    Volume
 * 64 =  0 db = relative volume  0 and:    Volume 32 = -6 db = relative
 * volume -8 it was implemented as a table because it is only 128 bytes and
 * it saves a lot of log() calculations. (Rob Hooft <hooft@chem.ruu.nl>)
 */

static char opl3_volume_table[128] =
{
	-63, -48, -40, -35, -32, -29, -27, -26,
	-24, -23, -21, -20, -19, -18, -18, -17,
	-16, -15, -15, -14, -13, -13, -12, -12,
	-11, -11, -10, -10, -10, -9, -9, -8,
	-8, -8, -7, -7, -7, -6, -6, -6,
	-5, -5, -5, -5, -4, -4, -4, -4,
	-3, -3, -3, -3, -2, -2, -2, -2,
	-2, -1, -1, -1, -1, 0, 0, 0,
	0, 0, 0, 1, 1, 1, 1, 1,
	1, 2, 2, 2, 2, 2, 2, 2,
	3, 3, 3, 3, 3, 3, 3, 4,
	4, 4, 4, 4, 4, 4, 4, 5,
	5, 5, 5, 5, 5, 5, 5, 5,
	6, 6, 6, 6, 6, 6, 6, 6,
	6, 7, 7, 7, 7, 7, 7, 7,
	7, 7, 7, 8, 8, 8, 8, 8
};

void snd_opl3_calc_volume(unsigned char *volbyte, int vel,
			  struct snd_midi_channel *chan)
{
	int oldvol, newvol, n;
	int volume;

	volume = (vel * chan->gm_volume * chan->gm_expression) / (127*127);
	if (volume > 127)
		volume = 127;

	oldvol = OPL3_TOTAL_LEVEL_MASK - (*volbyte & OPL3_TOTAL_LEVEL_MASK);

	newvol = opl3_volume_table[volume] + oldvol;
	if (newvol > OPL3_TOTAL_LEVEL_MASK)
		newvol = OPL3_TOTAL_LEVEL_MASK;
	else if (newvol < 0)
		newvol = 0;

	n = OPL3_TOTAL_LEVEL_MASK - (newvol & OPL3_TOTAL_LEVEL_MASK);

	*volbyte = (*volbyte & OPL3_KSL_MASK) | (n & OPL3_TOTAL_LEVEL_MASK);
}

/*
 * Converts the note frequency to block and fnum values for the FM chip
 */
static short opl3_note_table[16] =
{
	305, 323,	/* for pitch bending, -2 semitones */
	343, 363, 385, 408, 432, 458, 485, 514, 544, 577, 611, 647,
	686, 726	/* for pitch bending, +2 semitones */
};

static void snd_opl3_calc_pitch(unsigned char *fnum, unsigned char *blocknum,
				int note, struct snd_midi_channel *chan)
{
	int block = ((note / 12) & 0x07) - 1;
	int idx = (note % 12) + 2;
	int freq;

	if (chan->midi_pitchbend) {
		int pitchbend = chan->midi_pitchbend;
		int segment;

		if (pitchbend > 0x1FFF)
			pitchbend = 0x1FFF;

		segment = pitchbend / 0x1000;
		freq = opl3_note_table[idx+segment];
		freq += ((opl3_note_table[idx+segment+1] - freq) *
			 (pitchbend % 0x1000)) / 0x1000;
	} else {
		freq = opl3_note_table[idx];
	}

	*fnum = (unsigned char) freq;
	*blocknum = ((freq >> 8) & OPL3_FNUM_HIGH_MASK) |
		((block << 2) & OPL3_BLOCKNUM_MASK);
}


#ifdef DEBUG_ALLOC
static void debug_alloc(struct snd_opl3 *opl3, char *s, int voice) {
	int i;
	char *str = "x.24";

	printk("time %.5i: %s [%.2i]: ", opl3->use_time, s, voice);
	for<