ALSA: seq: potential out of bounds in do_control()

[mirror_ubuntu-bionic-kernel.git] / sound / core / seq / seq_midi_emul.c

/*
 *  GM/GS/XG midi module.
 *
 *  Copyright (C) 1999 Steve Ratcliffe
 *
 *  Based on awe_wave.c by Takashi Iwai
 *
 *   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
 *
 */
/*
 * This module is used to keep track of the current midi state.
 * It can be used for drivers that are required to emulate midi when
 * the hardware doesn't.
 *
 * It was written for a AWE64 driver, but there should be no AWE specific
 * code in here.  If there is it should be reported as a bug.
 */

#include <linux/init.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/module.h>
#include <sound/core.h>
#include <sound/seq_kernel.h>
#include <sound/seq_midi_emul.h>
#include <sound/initval.h>
#include <sound/asoundef.h>

MODULE_AUTHOR("Takashi Iwai / Steve Ratcliffe");
MODULE_DESCRIPTION("Advanced Linux Sound Architecture sequencer MIDI emulation.");
MODULE_LICENSE("GPL");

/* Prototypes for static functions */
static void note_off(struct snd_midi_op *ops, void *drv,
                     struct snd_midi_channel *chan,
                     int note, int vel);
static void do_control(struct snd_midi_op *ops, void *private,
                       struct snd_midi_channel_set *chset,
                       struct snd_midi_channel *chan,
                       int control, int value);
static void rpn(struct snd_midi_op *ops, void *drv, struct snd_midi_channel *chan,
                struct snd_midi_channel_set *chset);
static void nrpn(struct snd_midi_op *ops, void *drv, struct snd_midi_channel *chan,
                 struct snd_midi_channel_set *chset);
static void sysex(struct snd_midi_op *ops, void *private, unsigned char *sysex,
                  int len, struct snd_midi_channel_set *chset);
static void all_sounds_off(struct snd_midi_op *ops, void *private,
                           struct snd_midi_channel *chan);
static void all_notes_off(struct snd_midi_op *ops, void *private,
                          struct snd_midi_channel *chan);
static void snd_midi_reset_controllers(struct snd_midi_channel *chan);
static void reset_all_channels(struct snd_midi_channel_set *chset);


/*
 * Process an event in a driver independent way.  This means dealing
 * with RPN, NRPN, SysEx etc that are defined for common midi applications
 * such as GM, GS and XG.
 * There modes that this module will run in are:
 *   Generic MIDI - no interpretation at all, it will just save current values
 *                  of controllers etc.
 *   GM - You can use all gm_ prefixed elements of chan.  Controls, RPN, NRPN,
 *        SysEx will be interpreded as defined in General Midi.
 *   GS - You can use all gs_ prefixed elements of chan. Codes for GS will be
 *        interpreted.
 *   XG - You can use all xg_ prefixed elements of chan.  Codes for XG will
 *        be interpreted.
 */
void
snd_midi_process_event(struct snd_midi_op *ops,
                       struct snd_seq_event *ev,
                       struct snd_midi_channel_set *chanset)
{
        struct snd_midi_channel *chan;
        void *drv;
        int dest_channel = 0;

        if (ev == NULL || chanset == NULL) {
                pr_debug("ALSA: seq_midi_emul: ev or chanbase NULL (snd_midi_process_event)\n");
                return;
        }
        if (chanset->channels == NULL)
                return;

        if (snd_seq_ev_is_channel_type(ev)) {
                dest_channel = ev->data.note.channel;
                if (dest_channel >= chanset->max_channels) {
                        pr_debug("ALSA: seq_midi_emul: dest channel is %d, max is %d\n",
                                   dest_channel, chanset->max_channels);
                        return;
                }
        }

        chan = chanset->channels + dest_channel;
        drv  = chanset->private_data;

        /* EVENT_NOTE should be processed before queued */
        if (ev->type == SNDRV_SEQ_EVENT_NOTE)
                return;

        /* Make sure that we don't have a note on that should really be
         * a note off */
        if (ev->type == SNDRV_SEQ_EVENT_NOTEON && ev->data.note.velocity == 0)
                ev->type = SNDRV_SEQ_EVENT_NOTEOFF;

        /* Make sure the note is within array range */
        if (ev->type == SNDRV_SEQ_EVENT_NOTEON ||
            ev->type == SNDRV_SEQ_EVENT_NOTEOFF ||
            ev->type == SNDRV_SEQ_EVENT_KEYPRESS) {
                if (ev->data.note.note >= 128)
                        return;
        }

        switch (ev->type) {
        case SNDRV_SEQ_EVENT_NOTEON:
                if (chan->note[ev->data.note.note] & SNDRV_MIDI_NOTE_ON) {
                        if (ops->note_off)
                                ops->note_off(drv, ev->data.note.note, 0, chan);
                }
                chan->note[ev->data.note.note] = SNDRV_MIDI_NOTE_ON;
                if (ops->note_on)
                        ops->note_on(drv, ev->data.note.note, ev->data.note.velocity, chan);
                break;
        case SNDRV_SEQ_EVENT_NOTEOFF:
                if (! (chan->note[ev->data.note.note] & SNDRV_MIDI_NOTE_ON))
                        break;
                if (ops->note_off)
                        note_off(ops, drv, chan, ev->data.note.note, ev->data.note.velocity);
                break;
        case SNDRV_SEQ_EVENT_KEYPRESS:
                if (ops->key_press)
                        ops->key_press(drv, ev->data.note.note, ev->data.note.velocity, chan);
                break;
        case SNDRV_SEQ_EVENT_CONTROLLER:
                do_control(ops, drv, chanset, chan,
                           ev->data.control.param, ev->data.control.value);
                break;
        case SNDRV_SEQ_EVENT_PGMCHANGE:
                chan->midi_program = ev->data.control.value;
                break;
        case SNDRV_SEQ_EVENT_PITCHBEND:
                chan->midi_pitchbend = ev->data.control.value;
                if (ops->control)
                        ops->control(drv, MIDI_CTL_PITCHBEND, chan);
                break;
        case SNDRV_SEQ_EVENT_CHANPRESS:
                chan->midi_pressure = ev->data.control.value;
                if (ops->control)
                        ops->control(drv, MIDI_CTL_CHAN_PRESSURE, chan);
                break;
        case SNDRV_SEQ_EVENT_CONTROL14:
                /* Best guess is that this is any of the 14 bit controller values */
                if (ev->data.control.param < 32) {
                        /* set low part first */
                        chan->control[ev->data.control.param + 32] =
                                ev->data.control.value & 0x7f;
                        do_control(ops, drv, chanset, chan,
                                   ev->data.control.param,
                                   ((ev->data.control.value>>7) & 0x7f));
                } else
                        do_control(ops, drv, chanset, chan,
                                   ev->data.control.param,
                                   ev->data.control.value);
                break;
        case SNDRV_SEQ_EVENT_NONREGPARAM:
                /* Break it back into its controller values */
                chan->param_type = SNDRV_MIDI_PARAM_TYPE_NONREGISTERED;
                chan->control[MIDI_CTL_MSB_DATA_ENTRY]
                        = (ev->data.control.value >> 7) & 0x7f;
                chan->control[MIDI_CTL_LSB_DATA_ENTRY]
                        = ev->data.control.value & 0x7f;
                chan->control[MIDI_CTL_NONREG_PARM_NUM_MSB]
                        = (ev->data.control.param >> 7) & 0x7f;
                chan->control[MIDI_CTL_NONREG_PARM_NUM_LSB]
                        = ev->data.control.param & 0x7f;
                nrpn(ops, drv, chan, chanset);
                break;
        case SNDRV_SEQ_EVENT_REGPARAM:
                /* Break it back into its controller values */
                chan->param_type = SNDRV_MIDI_PARAM_TYPE_REGISTERED;
                chan->control[MIDI_CTL_MSB_DATA_ENTRY]
                        = (ev->data.control.value >> 7) & 0x7f;
                chan->control[MIDI_CTL_LSB_DATA_ENTRY]
                        = ev->data.control.value & 0x7f;
                chan->control[MIDI_CTL_REGIST_PARM_NUM_MSB]
                        = (ev->data.control.param >> 7) & 0x7f;
                chan->control[MIDI_CTL_REGIST_PARM_NUM_LSB]
                        = ev->data.control.param & 0x7f;
                rpn(ops, drv, chan, chanset);
                break;
        case SNDRV_SEQ_EVENT_SYSEX:
                if ((ev->flags & SNDRV_SEQ_EVENT_LENGTH_MASK) == SNDRV_SEQ_EVENT_LENGTH_VARIABLE) {
                        unsigned char sysexbuf[64];
                        int len;
                        len = snd_seq_expand_var_event(ev, sizeof(sysexbuf), sysexbuf, 1, 0);
                        if (len > 0)
                                sysex(ops, drv, sysexbuf, len, chanset);
                }
                break;
        case SNDRV_SEQ_EVENT_SONGPOS:
        case SNDRV_SEQ_EVENT_SONGSEL:
        case SNDRV_SEQ_EVENT_CLOCK:
        case SNDRV_SEQ_EVENT_START:
        case SNDRV_SEQ_EVENT_CONTINUE:
        case SNDRV_SEQ_EVENT_STOP:
        case SNDRV_SEQ_EVENT_QFRAME:
        case SNDRV_SEQ_EVENT_TEMPO:
        case SNDRV_SEQ_EVENT_TIMESIGN:
        case SNDRV_SEQ_EVENT_KEYSIGN:
                goto not_yet;
        case SNDRV_SEQ_EVENT_SENSING:
                break;
        case SNDRV_SEQ_EVENT_CLIENT_START:
        case SNDRV_SEQ_EVENT_CLIENT_EXIT:
        case SNDRV_SEQ_EVENT_CLIENT_CHANGE:
        case SNDRV_SEQ_EVENT_PORT_START:
        case SNDRV_SEQ_EVENT_PORT_EXIT:
        case SNDRV_SEQ_EVENT_PORT_CHANGE:
        case SNDRV_SEQ_EVENT_ECHO:
        not_yet:
        default:
                /*pr_debug("ALSA: seq_midi_emul: Unimplemented event %d\n", ev->type);*/
                break;
        }
}


/*
 * release note
 */
static void
note_off(struct snd_midi_op *ops, void *drv, struct snd_midi_channel *chan,
         int note, int vel)
{
        if (chan->gm_hold) {
                /* Hold this note until pedal is turned off */
                chan->note[note] |= SNDRV_MIDI_NOTE_RELEASED;
        } else if (chan->note[note] & SNDRV_MIDI_NOTE_SOSTENUTO) {
                /* Mark this note as release; it will be turned off when sostenuto
                 * is turned off */
                chan->note[note] |= SNDRV_MIDI_NOTE_RELEASED;
        } else {
                chan->note[note] = 0;
                if (ops->note_off)
                        ops->note_off(drv, note, vel, chan);
        }
}

/*
 * Do all driver independent operations for this controller and pass
 * events that need to take place immediately to the driver.
 */
static void
do_control(struct snd_midi_op *ops, void *drv, struct snd_midi_channel_set *chset,
           struct snd_midi_channel *chan, int control, int value)
{
        int  i;

        if (control >= ARRAY_SIZE(chan->control))
                return;

        /* Switches */
        if ((control >=64 && control <=69) || (control >= 80 && control <= 83)) {
                /* These are all switches; either off or on so set to 0 or 127 */
                value = (value >= 64)? 127: 0;
        }
        chan->control[control] = value;

        switch (control) {
        case MIDI_CTL_SUSTAIN:
                if (value == 0) {
                        /* Sustain has been released, turn off held notes */
                        for (i = 0; i < 128; i++) {
                                if (chan->note[i] & SNDRV_MIDI_NOTE_RELEASED) {
                                        chan->note[i] = SNDRV_MIDI_NOTE_OFF;
                                        if (ops->note_off)
                                                ops->note_off(drv, i, 0, chan);
                                }
                        }
                }
                break;
        case MIDI_CTL_PORTAMENTO:
                break;
        case MIDI_CTL_SOSTENUTO:
                if (value) {
                        /* Mark each note that is currently held down */
                        for (i = 0; i < 128; i++) {
                                if (chan->note[i] & SNDRV_MIDI_NOTE_ON)
                                        chan->note[i] |= SNDRV_MIDI_NOTE_SOSTENUTO;
                        }
                } else {
                        /* release all notes that were held */
                        for (i = 0; i < 128; i++) {
                                if (chan->note[i] & SNDRV_MIDI_NOTE_SOSTENUTO) {
                                        chan->note[i] &= ~SNDRV_MIDI_NOTE_SOSTENUTO;
                                        if (chan->note[i] & SNDRV_MIDI_NOTE_RELEASED) {
                                                chan->note[i] = SNDRV_MIDI_NOTE_OFF;
                                                if (ops->note_off)
                                                        ops->note_off(drv, i, 0, chan);
                                        }
                                }
                        }
                }
                break;
        case MIDI_CTL_MSB_DATA_ENTRY:
                chan->control[MIDI_CTL_LSB_DATA_ENTRY] = 0;
                /* go through here */
        case MIDI_CTL_LSB_DATA_ENTRY:
                if (chan->param_type == SNDRV_MIDI_PARAM_TYPE_REGISTERED)
                        rpn(ops, drv, chan, chset);
                else
                        nrpn(ops, drv, chan, chset);
                break;
        case MIDI_CTL_REGIST_PARM_NUM_LSB:
        case MIDI_CTL_REGIST_PARM_NUM_MSB:
                chan->param_type = SNDRV_MIDI_PARAM_TYPE_REGISTERED;
                break;
        case MIDI_CTL_NONREG_PARM_NUM_LSB:
        case MIDI_CTL_NONREG_PARM_NUM_MSB:
                chan->param_type = SNDRV_MIDI_PARAM_TYPE_NONREGISTERED;
                break;

        case MIDI_CTL_ALL_SOUNDS_OFF:
                all_sounds_off(ops, drv, chan);
                break;

        case MIDI_CTL_ALL_NOTES_OFF:
                all_notes_off(ops, drv, chan);
                break;

        case MIDI_CTL_MSB_BANK:
                if (chset->midi_mode == SNDRV_MIDI_MODE_XG) {
                        if (value == 127)
                                chan->drum_channel = 1;
                        else
                                chan->drum_channel = 0;
                }
                break;
        case MIDI_CTL_LSB_BANK:
                break;

        case MIDI_CTL_RESET_CONTROLLERS:
                snd_midi_reset_controllers(chan);
                break;

        case MIDI_CTL_SOFT_PEDAL:
        case MIDI_CTL_LEGATO_FOOTSWITCH:
        case MIDI_CTL_HOLD2:
        case MIDI_CTL_SC1_SOUND_VARIATION:
        case MIDI_CTL_SC2_TIMBRE:
        case MIDI_CTL_SC3_RELEASE_TIME:
        case MIDI_CTL_SC4_ATTACK_TIME:
        case MIDI_CTL_SC5_BRIGHTNESS:
        case MIDI_CTL_E1_REVERB_DEPTH:
        case MIDI_CTL_E2_TREMOLO_DEPTH:
        case MIDI_CTL_E3_CHORUS_DEPTH:
        case MIDI_CTL_E4_DETUNE_DEPTH:
        case MIDI_CTL_E5_PHASER_DEPTH:
                goto notyet;
        notyet:
        default:
                if (ops->control)
                        ops->control(drv, control, chan);
                break;
        }
}


/*
 * initialize the MIDI status
 */
void
snd_midi_channel_set_clear(struct snd_midi_channel_set *chset)
{
        int i;

        chset->midi_mode = SNDRV_MIDI_MODE_GM;
        chset->gs_master_volume = 127;

        for (i = 0; i < chset->max_channels; i++) {
                struct snd_midi_channel *chan = chset->channels + i;
                memset(chan->note, 0, sizeof(chan->note));

                chan->midi_aftertouch = 0;
                chan->midi_pressure = 0;
                chan->midi_program = 0;
                chan->midi_pitchbend = 0;
                snd_midi_reset_controllers(chan);
                chan->gm_rpn_pitch_bend_range = 256; /* 2 semitones */
                chan->gm_rpn_fine_tuning = 0;
                chan->gm_rpn_coarse_tuning = 0;

                if (i == 9)
                        chan->drum_channel = 1;
                else
                        chan->drum_channel = 0;
        }
}

/*
 * Process a rpn message.
 */
static void
rpn(struct snd_midi_op *ops, void *drv, struct snd_midi_channel *chan,
    struct snd_midi_channel_set *chset)
{
        int type;
        int val;

        if (chset->midi_mode != SNDRV_MIDI_MODE_NONE) {
                type = (chan->control[MIDI_CTL_REGIST_PARM_NUM_MSB] << 8) |
                        chan->control[MIDI_CTL_REGIST_PARM_NUM_LSB];
                val = (chan->control[MIDI_CTL_MSB_DATA_ENTRY] << 7) |
                        chan->control[MIDI_CTL_LSB_DATA_ENTRY];

                switch (type) {
                case 0x0000: /* Pitch bend sensitivity */
                        /* MSB only / 1 semitone per 128 */
                        chan->gm_rpn_pitch_bend_range = val;
                        break;
                                        
                case 0x0001: /* fine tuning: */
                        /* MSB/LSB, 8192=center, 100/8192 cent step */
                        chan->gm_rpn_fine_tuning = val - 8192;
                        break;

                case 0x0002: /* coarse tuning */
                        /* MSB only / 8192=center, 1 semitone per 128 */
                        chan->gm_rpn_coarse_tuning = val - 8192;
                        break;

                case 0x7F7F: /* "lock-in" RPN */
                        /* ignored */
                        break;
                }
        }
        /* should call nrpn or rpn callback here.. */
}

/*
 * Process an nrpn message.
 */
static void
nrpn(struct snd_midi_op *ops, void *drv, struct snd_midi_channel *chan,
     struct snd_midi_channel_set *chset)
{
        /* parse XG NRPNs here if possible */
        if (ops->nrpn)
                ops->nrpn(drv, chan, chset);
}


/*
 * convert channel parameter in GS sysex
 */
static int
get_channel(unsigned char cmd)
{
        int p = cmd & 0x0f;
        if (p == 0)
                p = 9;
        else if (p < 10)
                p--;
        return p;
}


/*
 * Process a sysex message.
 */
static void
sysex(struct snd_midi_op *ops, void *private, unsigned char *buf, int len,
      struct snd_midi_channel_set *chset)
{
        /* GM on */
        static unsigned char gm_on_macro[] = {
                0x7e,0x7f,0x09,0x01,
        };
        /* XG on */
        static unsigned char xg_on_macro[] = {
                0x43,0x10,0x4c,0x00,0x00,0x7e,0x00,
        };
        /* GS prefix
         * drum channel: XX=0x1?(channel), YY=0x15, ZZ=on/off
         * reverb mode: XX=0x01, YY=0x30, ZZ=0-7
         * chorus mode: XX=0x01, YY=0x38, ZZ=0-7
         * master vol:  XX=0x00, YY=0x04, ZZ=0-127
         */
        static unsigned char gs_pfx_macro[] = {
                0x41,0x10,0x42,0x12,0x40,/*XX,YY,ZZ*/
        };

        int parsed = SNDRV_MIDI_SYSEX_NOT_PARSED;

        if (len <= 0 || buf[0] != 0xf0)
                return;
        /* skip first byte */
        buf++;
        len--;

        /* GM on */
        if (len >= (int)sizeof(gm_on_macro) &&
            memcmp(buf, gm_on_macro, sizeof(gm_on_macro)) == 0) {
                if (chset->midi_mode != SNDRV_MIDI_MODE_GS &&
                    chset->midi_mode != SNDRV_MIDI_MODE_XG) {
                        chset->midi_mode = SNDRV_MIDI_MODE_GM;
                        reset_all_channels(chset);
                        parsed = SNDRV_MIDI_SYSEX_GM_ON;
                }
        }

        /* GS macros */
        else if (len >= 8 &&
                 memcmp(buf, gs_pfx_macro, sizeof(gs_pfx_macro)) == 0) {
                if (chset->midi_mode != SNDRV_MIDI_MODE_GS &&
                    chset->midi_mode != SNDRV_MIDI_MODE_XG)
                        chset->midi_mode = SNDRV_MIDI_MODE_GS;

                if (buf[5] == 0x00 && buf[6] == 0x7f && buf[7] == 0x00) {
                        /* GS reset */
                        parsed = SNDRV_MIDI_SYSEX_GS_RESET;
                        reset_all_channels(chset);
                }

                else if ((buf[5] & 0xf0) == 0x10 && buf[6] == 0x15) {
                        /* drum pattern */
                        int p = get_channel(buf[5]);
                        if (p < chset->max_channels) {
                                parsed = SNDRV_MIDI_SYSEX_GS_DRUM_CHANNEL;
                                if (buf[7])
                                        chset->channels[p].drum_channel = 1;
                                else
                                        chset->channels[p].drum_channel = 0;
                        }

                } else if ((buf[5] & 0xf0) == 0x10 && buf[6] == 0x21) {
                        /* program */
                        int p = get_channel(buf[5]);
                        if (p < chset->max_channels &&
                            ! chset->channels[p].drum_channel) {
                                parsed = SNDRV_MIDI_SYSEX_GS_DRUM_CHANNEL;
                                chset->channels[p].midi_program = buf[7];
                        }

                } else if (buf[5] == 0x01 && buf[6] == 0x30) {
                        /* reverb mode */
                        parsed = SNDRV_MIDI_SYSEX_GS_REVERB_MODE;
                        chset->gs_reverb_mode = buf[7];

                } else if (buf[5] == 0x01 && buf[6] == 0x38) {
                        /* chorus mode */
                        parsed = SNDRV_MIDI_SYSEX_GS_CHORUS_MODE;
                        chset->gs_chorus_mode = buf[7];

                } else if (buf[5] == 0x00 && buf[6] == 0x04) {
                        /* master volume */
                        parsed = SNDRV_MIDI_SYSEX_GS_MASTER_VOLUME;
                        chset->gs_master_volume = buf[7];

                }
        }

        /* XG on */
        else if (len >= (int)sizeof(xg_on_macro) &&
                 memcmp(buf, xg_on_macro, sizeof(xg_on_macro)) == 0) {
                int i;
                chset->midi_mode = SNDRV_MIDI_MODE_XG;
                parsed = SNDRV_MIDI_SYSEX_XG_ON;
                /* reset CC#0 for drums */
                for (i = 0; i < chset->max_channels; i++) {
                        if (chset->channels[i].drum_channel)
                                chset->channels[i].control[MIDI_CTL_MSB_BANK] = 127;
                        else
                                chset->channels[i].control[MIDI_CTL_MSB_BANK] = 0;
                }
        }

        if (ops->sysex)
                ops->sysex(private, buf - 1, len + 1, parsed, chset);
}

/*
 * all sound off
 */
static void
all_sounds_off(struct snd_midi_op *ops, void *drv, struct snd_midi_channel *chan)
{
        int n;

        if (! ops->note_terminate)
                return;
        for (n = 0; n < 128; n++) {
                if (chan->note[n]) {
                        ops->note_terminate(drv, n, chan);
                        chan->note[n] = 0;
                }
        }
}

/*
 * all notes off
 */
static void
all_notes_off(struct snd_midi_op *ops, void *drv, struct snd_midi_channel *chan)
{
        int n;

        if (! ops->note_off)
                return;
        for (n = 0; n < 128; n++) {
                if (chan->note[n] == SNDRV_MIDI_NOTE_ON)
                        note_off(ops, drv, chan, n, 0);
        }
}

/*
 * Initialise a single midi channel control block.
 */
static void snd_midi_channel_init(struct snd_midi_channel *p, int n)
{
        if (p == NULL)
                return;

        memset(p, 0, sizeof(struct snd_midi_channel));
        p->private = NULL;
        p->number = n;

        snd_midi_reset_controllers(p);
        p->gm_rpn_pitch_bend_range = 256; /* 2 semitones */
        p->gm_rpn_fine_tuning = 0;
        p->gm_rpn_coarse_tuning = 0;

        if (n == 9)
                p->drum_channel = 1;    /* Default ch 10 as drums */
}

/*
 * Allocate and initialise a set of midi channel control blocks.
 */
static struct snd_midi_channel *snd_midi_channel_init_set(int n)
{
        struct snd_midi_channel *chan;
        int  i;

        chan = kmalloc(n * sizeof(struct snd_midi_channel), GFP_KERNEL);
        if (chan) {
                for (i = 0; i < n; i++)
                        snd_midi_channel_init(chan+i, i);
        }

        return chan;
}

/*
 * reset all midi channels
 */
static void
reset_all_channels(struct snd_midi_channel_set *chset)
{
        int ch;
        for (ch = 0; ch < chset->max_channels; ch++) {
                struct snd_midi_channel *chan = chset->channels + ch;
                snd_midi_reset_controllers(chan);
                chan->gm_rpn_pitch_bend_range = 256; /* 2 semitones */
                chan->gm_rpn_fine_tuning = 0;
                chan->gm_rpn_coarse_tuning = 0;

                if (ch == 9)
                        chan->drum_channel = 1;
                else
                        chan->drum_channel = 0;
        }
}


/*
 * Allocate and initialise a midi channel set.
 */
struct snd_midi_channel_set *snd_midi_channel_alloc_set(int n)
{
        struct snd_midi_channel_set *chset;

        chset = kmalloc(sizeof(*chset), GFP_KERNEL);
        if (chset) {
                chset->channels = snd_midi_channel_init_set(n);
                chset->private_data = NULL;
                chset->max_channels = n;
        }
        return chset;
}

/*
 * Reset the midi controllers on a particular channel to default values.
 */
static void snd_midi_reset_controllers(struct snd_midi_channel *chan)
{
        memset(chan->control, 0, sizeof(chan->control));
        chan->gm_volume = 127;
        chan->gm_expression = 127;
        chan->gm_pan = 64;
}


/*
 * Free a midi channel set.
 */
void snd_midi_channel_free_set(struct snd_midi_channel_set *chset)
{
        if (chset == NULL)
                return;
        kfree(chset->channels);
        kfree(chset);
}

static int __init alsa_seq_midi_emul_init(void)
{
        return 0;
}

static void __exit alsa_seq_midi_emul_exit(void)
{
}

module_init(alsa_seq_midi_emul_init)
module_exit(alsa_seq_midi_emul_exit)

EXPORT_SYMBOL(snd_midi_process_event);
EXPORT_SYMBOL(snd_midi_channel_set_clear);
EXPORT_SYMBOL(snd_midi_channel_alloc_set);
EXPORT_SYMBOL(snd_midi_channel_free_set);