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midisyn.c revision 1.5.10.2
      1  1.5.10.2    bouyer /*	$NetBSD: midisyn.c,v 1.5.10.2 2001/02/11 19:15:17 bouyer Exp $	*/
      2       1.1  augustss 
      3       1.1  augustss /*
      4       1.1  augustss  * Copyright (c) 1998 The NetBSD Foundation, Inc.
      5       1.1  augustss  * All rights reserved.
      6       1.1  augustss  *
      7       1.5  augustss  * This code is derived from software contributed to The NetBSD Foundation
      8       1.5  augustss  * by Lennart Augustsson (augustss (at) netbsd.org).
      9       1.1  augustss  *
     10       1.1  augustss  * Redistribution and use in source and binary forms, with or without
     11       1.1  augustss  * modification, are permitted provided that the following conditions
     12       1.1  augustss  * are met:
     13       1.1  augustss  * 1. Redistributions of source code must retain the above copyright
     14       1.1  augustss  *    notice, this list of conditions and the following disclaimer.
     15       1.1  augustss  * 2. Redistributions in binary form must reproduce the above copyright
     16       1.1  augustss  *    notice, this list of conditions and the following disclaimer in the
     17       1.1  augustss  *    documentation and/or other materials provided with the distribution.
     18       1.1  augustss  * 3. All advertising materials mentioning features or use of this software
     19       1.1  augustss  *    must display the following acknowledgement:
     20       1.1  augustss  *        This product includes software developed by the NetBSD
     21       1.1  augustss  *        Foundation, Inc. and its contributors.
     22       1.1  augustss  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23       1.1  augustss  *    contributors may be used to endorse or promote products derived
     24       1.1  augustss  *    from this software without specific prior written permission.
     25       1.1  augustss  *
     26       1.1  augustss  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27       1.1  augustss  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28       1.1  augustss  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29       1.1  augustss  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30       1.1  augustss  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31       1.1  augustss  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32       1.1  augustss  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33       1.1  augustss  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34       1.1  augustss  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35       1.1  augustss  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36       1.1  augustss  * POSSIBILITY OF SUCH DAMAGE.
     37       1.1  augustss  */
     38       1.1  augustss 
     39       1.1  augustss #include <sys/param.h>
     40       1.1  augustss #include <sys/ioctl.h>
     41       1.1  augustss #include <sys/fcntl.h>
     42       1.1  augustss #include <sys/vnode.h>
     43       1.1  augustss #include <sys/select.h>
     44       1.1  augustss #include <sys/proc.h>
     45       1.1  augustss #include <sys/malloc.h>
     46       1.1  augustss #include <sys/systm.h>
     47       1.1  augustss #include <sys/syslog.h>
     48       1.1  augustss #include <sys/kernel.h>
     49       1.1  augustss #include <sys/audioio.h>
     50       1.1  augustss #include <sys/midiio.h>
     51       1.1  augustss #include <sys/device.h>
     52       1.1  augustss 
     53       1.1  augustss #include <dev/audio_if.h>
     54       1.3  augustss #include <dev/midi_if.h>
     55       1.1  augustss #include <dev/midivar.h>
     56       1.1  augustss #include <dev/midisynvar.h>
     57       1.1  augustss 
     58       1.1  augustss #ifdef AUDIO_DEBUG
     59       1.1  augustss #define DPRINTF(x)	if (midisyndebug) printf x
     60       1.1  augustss #define DPRINTFN(n,x)	if (midisyndebug >= (n)) printf x
     61       1.1  augustss int	midisyndebug = 0;
     62       1.1  augustss #else
     63       1.1  augustss #define DPRINTF(x)
     64       1.1  augustss #define DPRINTFN(n,x)
     65       1.1  augustss #endif
     66       1.1  augustss 
     67       1.1  augustss int	midisyn_findvoice __P((midisyn *, int, int));
     68       1.1  augustss void	midisyn_freevoice __P((midisyn *, int));
     69       1.1  augustss int	midisyn_allocvoice __P((midisyn *, u_int32_t, u_int32_t));
     70       1.1  augustss u_int32_t midisyn_note_to_freq __P((int));
     71       1.3  augustss u_int32_t midisyn_finetune __P((u_int32_t, int, int, int));
     72       1.1  augustss 
     73       1.1  augustss int	midisyn_open __P((void *, int,
     74       1.1  augustss 			  void (*iintr)__P((void *, int)),
     75       1.1  augustss 			  void (*ointr)__P((void *)), void *arg));
     76       1.1  augustss void	midisyn_close __P((void *));
     77       1.1  augustss int	midisyn_output __P((void *, int));
     78       1.1  augustss void	midisyn_getinfo __P((void *, struct midi_info *));
     79       1.1  augustss int	midisyn_ioctl __P((void *, u_long, caddr_t, int, struct proc *));
     80       1.1  augustss 
     81       1.1  augustss struct midi_hw_if midisyn_hw_if = {
     82       1.1  augustss 	midisyn_open,
     83       1.1  augustss 	midisyn_close,
     84       1.1  augustss 	midisyn_output,
     85       1.1  augustss 	midisyn_getinfo,
     86       1.1  augustss 	midisyn_ioctl,
     87       1.1  augustss };
     88       1.1  augustss 
     89  1.5.10.2    bouyer static const int midi_lengths[] = { 3,3,3,3,2,2,3,1 };
     90       1.1  augustss /* Number of bytes in a MIDI command, including status */
     91       1.1  augustss #define MIDI_LENGTH(d) (midi_lengths[((d) >> 4) & 7])
     92       1.1  augustss 
     93       1.1  augustss int
     94       1.1  augustss midisyn_open(addr, flags, iintr, ointr, arg)
     95       1.1  augustss 	void *addr;
     96       1.1  augustss 	int flags;
     97       1.1  augustss 	void (*iintr)__P((void *, int));
     98       1.1  augustss 	void (*ointr)__P((void *));
     99       1.1  augustss 	void *arg;
    100       1.1  augustss {
    101       1.1  augustss 	midisyn *ms = addr;
    102       1.1  augustss 
    103       1.1  augustss 	DPRINTF(("midisyn_open: ms=%p ms->mets=%p\n", ms, ms->mets));
    104       1.1  augustss 	if (ms->mets->open)
    105       1.1  augustss 		return (ms->mets->open(ms, flags));
    106       1.1  augustss 	else
    107       1.1  augustss 		return (0);
    108       1.1  augustss }
    109       1.1  augustss 
    110       1.1  augustss void
    111       1.1  augustss midisyn_close(addr)
    112       1.1  augustss 	void *addr;
    113       1.1  augustss {
    114       1.1  augustss 	midisyn *ms = addr;
    115       1.4   mycroft 	struct midisyn_methods *fs;
    116       1.4   mycroft 	int v;
    117       1.1  augustss 
    118       1.1  augustss 	DPRINTF(("midisyn_close: ms=%p ms->mets=%p\n", ms, ms->mets));
    119       1.4   mycroft 	fs = ms->mets;
    120       1.4   mycroft 	for (v = 0; v < ms->nvoice; v++)
    121       1.4   mycroft 		if (ms->voices[v].inuse) {
    122       1.4   mycroft 			fs->noteoff(ms, v, 0, 0);
    123       1.4   mycroft 			midisyn_freevoice(ms, v);
    124       1.4   mycroft 		}
    125       1.4   mycroft 	if (fs->close)
    126       1.4   mycroft 		fs->close(ms);
    127       1.1  augustss }
    128       1.1  augustss 
    129       1.1  augustss void
    130       1.1  augustss midisyn_getinfo(addr, mi)
    131       1.1  augustss 	void *addr;
    132       1.1  augustss 	struct midi_info *mi;
    133       1.1  augustss {
    134       1.1  augustss 	midisyn *ms = addr;
    135       1.1  augustss 
    136       1.1  augustss 	mi->name = ms->name;
    137       1.1  augustss 	mi->props = 0;
    138       1.1  augustss }
    139       1.1  augustss 
    140       1.1  augustss int
    141       1.1  augustss midisyn_ioctl(maddr, cmd, addr, flag, p)
    142       1.1  augustss 	void *maddr;
    143       1.1  augustss 	u_long cmd;
    144       1.1  augustss 	caddr_t addr;
    145       1.1  augustss 	int flag;
    146       1.1  augustss 	struct proc *p;
    147       1.1  augustss {
    148       1.1  augustss 	midisyn *ms = maddr;
    149       1.1  augustss 
    150       1.1  augustss 	if (ms->mets->ioctl)
    151       1.1  augustss 		return (ms->mets->ioctl(ms, cmd, addr, flag, p));
    152       1.1  augustss 	else
    153       1.1  augustss 		return (EINVAL);
    154       1.1  augustss }
    155       1.1  augustss 
    156       1.1  augustss int
    157       1.1  augustss midisyn_findvoice(ms, chan, note)
    158       1.1  augustss 	midisyn *ms;
    159       1.1  augustss 	int chan, note;
    160       1.1  augustss {
    161       1.1  augustss 	u_int cn;
    162       1.1  augustss 	int v;
    163       1.1  augustss 
    164       1.1  augustss 	if (!(ms->flags & MS_DOALLOC))
    165       1.1  augustss 		return (chan);
    166       1.3  augustss 	cn = MS_CHANNOTE(chan, note);
    167       1.1  augustss 	for (v = 0; v < ms->nvoice; v++)
    168       1.3  augustss 		if (ms->voices[v].chan_note == cn && ms->voices[v].inuse)
    169       1.1  augustss 			return (v);
    170       1.1  augustss 	return (-1);
    171       1.1  augustss }
    172       1.1  augustss 
    173       1.1  augustss void
    174       1.3  augustss midisyn_attach(sc, ms)
    175       1.1  augustss 	struct midi_softc *sc;
    176       1.1  augustss 	midisyn *ms;
    177       1.1  augustss {
    178       1.1  augustss 	if (ms->flags & MS_DOALLOC) {
    179       1.1  augustss 		ms->voices = malloc(ms->nvoice * sizeof (struct voice),
    180       1.1  augustss 				    M_DEVBUF, M_WAITOK);
    181       1.1  augustss 		memset(ms->voices, 0, ms->nvoice * sizeof (struct voice));
    182       1.1  augustss 		ms->seqno = 1;
    183       1.1  augustss 		if (ms->mets->allocv == 0)
    184       1.1  augustss 			ms->mets->allocv = &midisyn_allocvoice;
    185       1.1  augustss 	}
    186       1.1  augustss 	sc->hw_if = &midisyn_hw_if;
    187       1.1  augustss 	sc->hw_hdl = ms;
    188       1.1  augustss 	DPRINTF(("midisyn_attach: ms=%p\n", sc->hw_hdl));
    189       1.1  augustss }
    190       1.1  augustss 
    191       1.1  augustss void
    192       1.1  augustss midisyn_freevoice(ms, voice)
    193       1.1  augustss 	midisyn *ms;
    194       1.1  augustss 	int voice;
    195       1.1  augustss {
    196       1.1  augustss 	if (!(ms->flags & MS_DOALLOC))
    197       1.1  augustss 		return;
    198       1.3  augustss 	ms->voices[voice].inuse = 0;
    199       1.1  augustss }
    200       1.1  augustss 
    201       1.1  augustss int
    202       1.1  augustss midisyn_allocvoice(ms, chan, note)
    203       1.1  augustss 	midisyn *ms;
    204       1.1  augustss 	u_int32_t chan, note;
    205       1.1  augustss {
    206       1.1  augustss 	int bestv, v;
    207       1.1  augustss 	u_int bestseq, s;
    208       1.1  augustss 
    209       1.1  augustss 	if (!(ms->flags & MS_DOALLOC))
    210       1.1  augustss 		return (chan);
    211       1.1  augustss 	/* Find a free voice, or if no free voice is found the oldest. */
    212       1.1  augustss 	bestv = 0;
    213       1.3  augustss 	bestseq = ms->voices[0].seqno + (ms->voices[0].inuse ? 0x40000000 : 0);
    214       1.1  augustss 	for (v = 1; v < ms->nvoice; v++) {
    215       1.1  augustss 		s = ms->voices[v].seqno;
    216       1.3  augustss 		if (ms->voices[v].inuse)
    217       1.3  augustss 			s += 0x40000000;
    218       1.1  augustss 		if (s < bestseq) {
    219       1.1  augustss 			bestseq = s;
    220       1.1  augustss 			bestv = v;
    221       1.1  augustss 		}
    222       1.1  augustss 	}
    223       1.3  augustss 	DPRINTFN(10,("midisyn_allocvoice: v=%d seq=%d cn=%x inuse=%d\n",
    224       1.3  augustss 		     bestv, ms->voices[bestv].seqno,
    225       1.3  augustss 		     ms->voices[bestv].chan_note,
    226       1.3  augustss 		     ms->voices[bestv].inuse));
    227       1.3  augustss #ifdef AUDIO_DEBUG
    228       1.3  augustss 	if (ms->voices[bestv].inuse)
    229       1.3  augustss 		DPRINTFN(1,("midisyn_allocvoice: steal %x\n",
    230       1.3  augustss 			    ms->voices[bestv].chan_note));
    231       1.3  augustss #endif
    232       1.3  augustss 	ms->voices[bestv].chan_note = MS_CHANNOTE(chan, note);
    233       1.1  augustss 	ms->voices[bestv].seqno = ms->seqno++;
    234       1.3  augustss 	ms->voices[bestv].inuse = 1;
    235       1.1  augustss 	return (bestv);
    236       1.1  augustss }
    237       1.1  augustss 
    238       1.1  augustss int
    239       1.1  augustss midisyn_output(addr, b)
    240       1.1  augustss 	void *addr;
    241       1.1  augustss 	int b;
    242       1.1  augustss {
    243       1.1  augustss 	midisyn *ms = addr;
    244       1.1  augustss 	u_int8_t status, chan;
    245       1.1  augustss 	int voice = 0;		/* initialize to keep gcc quiet */
    246       1.1  augustss 	struct midisyn_methods *fs;
    247       1.1  augustss 	u_int32_t note, vel;
    248       1.1  augustss 
    249       1.2  augustss 	DPRINTF(("midisyn_output: ms=%p b=0x%02x\n", ms, b));
    250       1.1  augustss 	fs = ms->mets;
    251       1.1  augustss 	if (ms->pos < 0) {
    252       1.1  augustss 		/* Doing SYSEX */
    253       1.2  augustss 		DPRINTF(("midisyn_output: sysex 0x%02x\n", b));
    254       1.1  augustss 		if (fs->sysex)
    255       1.1  augustss 			fs->sysex(ms, b);
    256       1.1  augustss 		if (b == MIDI_SYSEX_END)
    257       1.1  augustss 			ms->pos = 0;
    258       1.1  augustss 		return (0);
    259       1.1  augustss 	}
    260       1.1  augustss 	if (ms->pos == 0 && !MIDI_IS_STATUS(b))
    261       1.1  augustss 		ms->pos++;	/* repeat last status byte */
    262       1.1  augustss 	ms->buf[ms->pos++] = b;
    263       1.1  augustss 	status = ms->buf[0];
    264       1.1  augustss 	if (ms->pos < MIDI_LENGTH(status))
    265       1.1  augustss 		return (0);
    266       1.1  augustss 	/* Decode the MIDI command */
    267       1.1  augustss 	chan = MIDI_GET_CHAN(status);
    268       1.1  augustss 	note = ms->buf[1];
    269       1.1  augustss 	if (ms->flags & MS_FREQXLATE)
    270       1.1  augustss 		note = midisyn_note_to_freq(note);
    271       1.1  augustss 	vel = ms->buf[2];
    272       1.1  augustss 	switch (MIDI_GET_STATUS(status)) {
    273       1.1  augustss 	case MIDI_NOTEOFF:
    274       1.1  augustss 		voice = midisyn_findvoice(ms, chan, ms->buf[1]);
    275       1.1  augustss 		if (voice >= 0) {
    276       1.1  augustss 			fs->noteoff(ms, voice, note, vel);
    277       1.1  augustss 			midisyn_freevoice(ms, voice);
    278       1.1  augustss 		}
    279       1.1  augustss 		break;
    280       1.1  augustss 	case MIDI_NOTEON:
    281       1.1  augustss 		voice = fs->allocv(ms, chan, ms->buf[1]);
    282       1.1  augustss 		fs->noteon(ms, voice, note, vel);
    283       1.1  augustss 		break;
    284       1.1  augustss 	case MIDI_KEY_PRESSURE:
    285       1.1  augustss 		if (fs->keypres) {
    286       1.1  augustss 			voice = midisyn_findvoice(ms, voice, ms->buf[1]);
    287       1.1  augustss 			if (voice >= 0)
    288       1.1  augustss 				fs->keypres(ms, voice, note, vel);
    289       1.1  augustss 		}
    290       1.1  augustss 		break;
    291       1.1  augustss 	case MIDI_CTL_CHANGE:
    292       1.1  augustss 		if (fs->ctlchg)
    293       1.1  augustss 			fs->ctlchg(ms, chan, ms->buf[1], vel);
    294       1.1  augustss 		break;
    295       1.1  augustss 	case MIDI_PGM_CHANGE:
    296       1.1  augustss 		if (fs->pgmchg)
    297       1.1  augustss 			fs->pgmchg(ms, chan, ms->buf[1]);
    298       1.1  augustss 		break;
    299       1.1  augustss 	case MIDI_CHN_PRESSURE:
    300       1.1  augustss 		if (fs->chnpres) {
    301       1.1  augustss 			voice = midisyn_findvoice(ms, chan, ms->buf[1]);
    302       1.1  augustss 			if (voice >= 0)
    303       1.1  augustss 				fs->chnpres(ms, voice, note);
    304       1.1  augustss 		}
    305       1.1  augustss 		break;
    306       1.1  augustss 	case MIDI_PITCH_BEND:
    307       1.1  augustss 		if (fs->pitchb) {
    308       1.1  augustss 			voice = midisyn_findvoice(ms, chan, ms->buf[1]);
    309       1.1  augustss 			if (voice >= 0)
    310       1.1  augustss 				fs->pitchb(ms, chan, note, vel);
    311       1.1  augustss 		}
    312       1.1  augustss 		break;
    313       1.1  augustss 	case MIDI_SYSTEM_PREFIX:
    314       1.1  augustss 		if (fs->sysex)
    315       1.1  augustss 			fs->sysex(ms, status);
    316       1.1  augustss 		ms->pos = -1;
    317       1.1  augustss 		return (0);
    318       1.1  augustss 	}
    319       1.1  augustss 	ms->pos = 0;
    320       1.1  augustss 	return (0);
    321       1.1  augustss }
    322       1.1  augustss 
    323       1.1  augustss /*
    324       1.1  augustss  * Convert a MIDI note to the corresponding frequency.
    325       1.1  augustss  * The frequency is scaled by 2^16.
    326       1.1  augustss  */
    327       1.1  augustss u_int32_t
    328       1.1  augustss midisyn_note_to_freq(note)
    329       1.1  augustss 	int note;
    330       1.1  augustss {
    331       1.1  augustss 	int o, n, f;
    332       1.1  augustss #define BASE_OCTAVE 5
    333  1.5.10.2    bouyer 	static const u_int32_t notes[] = {
    334       1.1  augustss 		17145893, 18165441, 19245614, 20390018, 21602472, 22887021,
    335       1.1  augustss 		24247954, 25689813, 27217409, 28835840, 30550508, 32367136
    336       1.1  augustss 	};
    337       1.1  augustss 
    338       1.1  augustss 
    339       1.1  augustss 	o = note / 12;
    340       1.1  augustss 	n = note % 12;
    341       1.1  augustss 
    342       1.1  augustss 	f = notes[n];
    343       1.1  augustss 
    344       1.1  augustss 	if (o < BASE_OCTAVE)
    345       1.1  augustss 		f >>= (BASE_OCTAVE - o);
    346       1.1  augustss 	else if (o > BASE_OCTAVE)
    347       1.1  augustss 		f <<= (o - BASE_OCTAVE);
    348       1.1  augustss 	return (f);
    349       1.3  augustss }
    350       1.3  augustss 
    351       1.3  augustss u_int32_t
    352       1.3  augustss midisyn_finetune(base_freq, bend, range, vibrato_cents)
    353       1.3  augustss 	u_int32_t base_freq;
    354       1.3  augustss 	int bend;
    355       1.3  augustss 	int range;
    356       1.3  augustss 	int vibrato_cents;
    357       1.3  augustss {
    358  1.5.10.2    bouyer 	static const u_int16_t semitone_tuning[24] =
    359       1.3  augustss 	{
    360       1.3  augustss /*   0 */ 10000, 10595, 11225, 11892, 12599, 13348, 14142, 14983,
    361       1.3  augustss /*   8 */ 15874, 16818, 17818, 18877, 20000, 21189, 22449, 23784,
    362       1.3  augustss /*  16 */ 25198, 26697, 28284, 29966, 31748, 33636, 35636, 37755
    363       1.3  augustss 	};
    364  1.5.10.2    bouyer 	static const u_int16_t cent_tuning[100] =
    365       1.3  augustss 	{
    366       1.3  augustss /*   0 */ 10000, 10006, 10012, 10017, 10023, 10029, 10035, 10041,
    367       1.3  augustss /*   8 */ 10046, 10052, 10058, 10064, 10070, 10075, 10081, 10087,
    368       1.3  augustss /*  16 */ 10093, 10099, 10105, 10110, 10116, 10122, 10128, 10134,
    369       1.3  augustss /*  24 */ 10140, 10145, 10151, 10157, 10163, 10169, 10175, 10181,
    370       1.3  augustss /*  32 */ 10187, 10192, 10198, 10204, 10210, 10216, 10222, 10228,
    371       1.3  augustss /*  40 */ 10234, 10240, 10246, 10251, 10257, 10263, 10269, 10275,
    372       1.3  augustss /*  48 */ 10281, 10287, 10293, 10299, 10305, 10311, 10317, 10323,
    373       1.3  augustss /*  56 */ 10329, 10335, 10341, 10347, 10353, 10359, 10365, 10371,
    374       1.3  augustss /*  64 */ 10377, 10383, 10389, 10395, 10401, 10407, 10413, 10419,
    375       1.3  augustss /*  72 */ 10425, 10431, 10437, 10443, 10449, 10455, 10461, 10467,
    376       1.3  augustss /*  80 */ 10473, 10479, 10485, 10491, 10497, 10503, 10509, 10515,
    377       1.3  augustss /*  88 */ 10521, 10528, 10534, 10540, 10546, 10552, 10558, 10564,
    378       1.3  augustss /*  96 */ 10570, 10576, 10582, 10589
    379       1.3  augustss 	};
    380       1.3  augustss 	u_int32_t amount;
    381       1.3  augustss 	int negative, semitones, cents, multiplier;
    382       1.3  augustss 
    383       1.3  augustss 	if (range == 0)
    384       1.3  augustss 		return base_freq;
    385       1.3  augustss 
    386       1.3  augustss 	if (base_freq == 0)
    387       1.3  augustss 		return base_freq;
    388       1.3  augustss 
    389       1.3  augustss 	if (range >= 8192)
    390       1.3  augustss 		range = 8192;
    391       1.3  augustss 
    392       1.3  augustss 	bend = bend * range / 8192;
    393       1.3  augustss 	bend += vibrato_cents;
    394       1.3  augustss 
    395       1.3  augustss 	if (bend == 0)
    396       1.3  augustss 		return base_freq;
    397       1.3  augustss 
    398       1.3  augustss 	if (bend < 0) {
    399       1.3  augustss 		bend = -bend;
    400       1.3  augustss 		negative = 1;
    401       1.3  augustss 	} else
    402       1.3  augustss 		negative = 0;
    403       1.3  augustss 
    404       1.3  augustss 	if (bend > range)
    405       1.3  augustss 		bend = range;
    406       1.3  augustss 
    407       1.3  augustss 	multiplier = 1;
    408       1.3  augustss 	while (bend > 2399) {
    409       1.3  augustss 		multiplier *= 4;
    410       1.3  augustss 		bend -= 2400;
    411       1.3  augustss 	}
    412       1.3  augustss 
    413       1.3  augustss 	semitones = bend / 100;
    414       1.3  augustss 	if (semitones > 99)
    415       1.3  augustss 		semitones = 99;
    416       1.3  augustss 	cents = bend % 100;
    417       1.3  augustss 
    418       1.3  augustss 	amount = semitone_tuning[semitones] * multiplier * cent_tuning[cents]
    419       1.3  augustss 		/ 10000;
    420       1.3  augustss 
    421       1.3  augustss 	if (negative)
    422       1.3  augustss 		return (base_freq * 10000 / amount);	/* Bend down */
    423       1.3  augustss 	else
    424       1.3  augustss 		return (base_freq * amount / 10000);	/* Bend up */
    425       1.1  augustss }
    426       1.1  augustss 
    427