seq_midi_event.c

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/*
 *  MIDI byte <-> sequencer event coder
 *
 *  Copyright (C) 1998,99 Takashi Iwai <[email protected]>,
 *                        Jaroslav Kysela <[email protected]>
 *
 *   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
 */

#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/module.h>
#include <sound/core.h>
#include <sound/seq_kernel.h>
#include <sound/seq_midi_event.h>
#include <sound/asoundef.h>

MODULE_AUTHOR("Takashi Iwai <[email protected]>, Jaroslav Kysela <[email protected]>");
MODULE_DESCRIPTION("MIDI byte <-> sequencer event coder");
MODULE_LICENSE("GPL");

/* event type, index into status_event[] */
/* from 0 to 6 are normal commands (note off, on, etc.) for 0x9?-0xe? */
#define ST_INVALID  7
#define ST_SPECIAL  8
#define ST_SYSEX    ST_SPECIAL
/* from 8 to 15 are events for 0xf0-0xf7 */


/*
 * prototypes
 */
static void note_event(struct snd_midi_event *dev, struct snd_seq_event *ev);
static void one_param_ctrl_event(struct snd_midi_event *dev, struct snd_seq_event *ev);
static void pitchbend_ctrl_event(struct snd_midi_event *dev, struct snd_seq_event *ev);
static void two_param_ctrl_event(struct snd_midi_event *dev, struct snd_seq_event *ev);
static void one_param_event(struct snd_midi_event *dev, struct snd_seq_event *ev);
static void songpos_event(struct snd_midi_event *dev, struct snd_seq_event *ev);
static void note_decode(struct snd_seq_event *ev, unsigned char *buf);
static void one_param_decode(struct snd_seq_event *ev, unsigned char *buf);
static void pitchbend_decode(struct snd_seq_event *ev, unsigned char *buf);
static void two_param_decode(struct snd_seq_event *ev, unsigned char *buf);
static void songpos_decode(struct snd_seq_event *ev, unsigned char *buf);

/*
 * event list
 */
static struct status_event_list {
    int event;
    int qlen;
    void (*encode)(struct snd_midi_event *dev, struct snd_seq_event *ev);
    void (*decode)(struct snd_seq_event *ev, unsigned char *buf);
} status_event[] = {
    /* 0x80 - 0xef */
    {SNDRV_SEQ_EVENT_NOTEOFF,    2, note_event, note_decode},
    {SNDRV_SEQ_EVENT_NOTEON,     2, note_event, note_decode},
    {SNDRV_SEQ_EVENT_KEYPRESS,   2, note_event, note_decode},
    {SNDRV_SEQ_EVENT_CONTROLLER,     2, two_param_ctrl_event, two_param_decode},
    {SNDRV_SEQ_EVENT_PGMCHANGE,  1, one_param_ctrl_event, one_param_decode},
    {SNDRV_SEQ_EVENT_CHANPRESS,  1, one_param_ctrl_event, one_param_decode},
    {SNDRV_SEQ_EVENT_PITCHBEND,  2, pitchbend_ctrl_event, pitchbend_decode},
    /* invalid */
    {SNDRV_SEQ_EVENT_NONE,      -1, NULL, NULL},
    /* 0xf0 - 0xff */
    {SNDRV_SEQ_EVENT_SYSEX,      1, NULL, NULL}, /* sysex: 0xf0 */
    {SNDRV_SEQ_EVENT_QFRAME,     1, one_param_event, one_param_decode}, /* 0xf1 */
    {SNDRV_SEQ_EVENT_SONGPOS,    2, songpos_event, songpos_decode}, /* 0xf2 */
    {SNDRV_SEQ_EVENT_SONGSEL,    1, one_param_event, one_param_decode}, /* 0xf3 */
    {SNDRV_SEQ_EVENT_NONE,      -1, NULL, NULL}, /* 0xf4 */
    {SNDRV_SEQ_EVENT_NONE,      -1, NULL, NULL}, /* 0xf5 */
    {SNDRV_SEQ_EVENT_TUNE_REQUEST,   0, NULL, NULL}, /* 0xf6 */
    {SNDRV_SEQ_EVENT_NONE,      -1, NULL, NULL}, /* 0xf7 */
    {SNDRV_SEQ_EVENT_CLOCK,      0, NULL, NULL}, /* 0xf8 */
    {SNDRV_SEQ_EVENT_NONE,      -1, NULL, NULL}, /* 0xf9 */
    {SNDRV_SEQ_EVENT_START,      0, NULL, NULL}, /* 0xfa */
    {SNDRV_SEQ_EVENT_CONTINUE,   0, NULL, NULL}, /* 0xfb */
    {SNDRV_SEQ_EVENT_STOP,       0, NULL, NULL}, /* 0xfc */
    {SNDRV_SEQ_EVENT_NONE,      -1, NULL, NULL}, /* 0xfd */
    {SNDRV_SEQ_EVENT_SENSING,    0, NULL, NULL}, /* 0xfe */
    {SNDRV_SEQ_EVENT_RESET,      0, NULL, NULL}, /* 0xff */
};

static int extra_decode_ctrl14(struct snd_midi_event *dev, unsigned char *buf, int len,
                   struct snd_seq_event *ev);
static int extra_decode_xrpn(struct snd_midi_event *dev, unsigned char *buf, int count,
                 struct snd_seq_event *ev);

static struct extra_event_list {
    int event;
    int (*decode)(struct snd_midi_event *dev, unsigned char *buf, int len,
              struct snd_seq_event *ev);
} extra_event[] = {
    {SNDRV_SEQ_EVENT_CONTROL14, extra_decode_ctrl14},
    {SNDRV_SEQ_EVENT_NONREGPARAM, extra_decode_xrpn},
    {SNDRV_SEQ_EVENT_REGPARAM, extra_decode_xrpn},
};

/*
 *  new/delete record
 */

int snd_midi_event_new(int bufsize, struct snd_midi_event **rdev)
{
    struct snd_midi_event *dev;

    *rdev = NULL;
    dev = kzalloc(sizeof(*dev), GFP_KERNEL);
    if (dev == NULL)
        return -ENOMEM;
    if (bufsize > 0) {
        dev->buf = kmalloc(bufsize, GFP_KERNEL);
        if (dev->buf == NULL) {
            kfree(dev);
            return -ENOMEM;
        }
    }
    dev->bufsize = bufsize;
    dev->lastcmd = 0xff;
    dev->type = ST_INVALID;
    spin_lock_init(&dev->lock);
    *rdev = dev;
    return 0;
}

void snd_midi_event_free(struct snd_midi_event *dev)
{
    if (dev != NULL) {
        kfree(dev->buf);
        kfree(dev);
    }
}

/*
 * initialize record
 */
static inline void reset_encode(struct snd_midi_event *dev)
{
    dev->read = 0;
    dev->qlen = 0;
    dev->type = ST_INVALID;
}

void snd_midi_event_reset_encode(struct snd_midi_event *dev)
{
    unsigned long flags;

    spin_lock_irqsave(&dev->lock, flags);
    reset_encode(dev);
    spin_unlock_irqrestore(&dev->lock, flags);
}

void snd_midi_event_reset_decode(struct snd_midi_event *dev)
{
    unsigned long flags;

    spin_lock_irqsave(&dev->lock, flags);
    dev->lastcmd = 0xff;
    spin_unlock_irqrestore(&dev->lock, flags);
}

#if 0
void snd_midi_event_init(struct snd_midi_event *dev)
{
    snd_midi_event_reset_encode(dev);
    snd_midi_event_reset_decode(dev);
}
#endif  /*  0  */

void snd_midi_event_no_status(struct snd_midi_event *dev, int on)
{
    dev->nostat = on ? 1 : 0;
}

/*
 * resize buffer
 */
#if 0
int snd_midi_event_resize_buffer(struct snd_midi_event *dev, int bufsize)
{
    unsigned char *new_buf, *old_buf;
    unsigned long flags;

    if (bufsize == dev->bufsize)
        return 0;
    new_buf = kmalloc(bufsize, GFP_KERNEL);
    if (new_buf == NULL)
        return -ENOMEM;
    spin_lock_irqsave(&dev->lock, flags);
    old_buf = dev->buf;
    dev->buf = new_buf;
    dev->bufsize = bufsize;
    reset_encode(dev);
    spin_unlock_irqrestore(&dev->lock, flags);
    kfree(old_buf);
    return 0;
}
#endif  /*  0  */

/*
 *  read bytes and encode to sequencer event if finished
 *  return the size of encoded bytes
 */
long snd_midi_event_encode(struct snd_midi_event *dev, unsigned char *buf, long count,
               struct snd_seq_event *ev)
{
    long result = 0;
    int rc;

    ev->type = SNDRV_SEQ_EVENT_NONE;

    while (count-- > 0) {
        rc = snd_midi_event_encode_byte(dev, *buf++, ev);
        result++;
        if (rc < 0)
            return rc;
        else if (rc > 0)
            return result;
    }

    return result;
}

/*
 *  read one byte and encode to sequencer event:
 *  return 1 if MIDI bytes are encoded to an event
 *         0 data is not finished
 *         negative for error
 */
int snd_midi_event_encode_byte(struct snd_midi_event *dev, int c,
                   struct snd_seq_event *ev)
{
    int rc = 0;
    unsigned long flags;

    c &= 0xff;

    if (c >= MIDI_CMD_COMMON_CLOCK) {
        /* real-time event */
        ev->type = status_event[ST_SPECIAL + c - 0xf0].event;
        ev->flags &= ~SNDRV_SEQ_EVENT_LENGTH_MASK;
        ev->flags |= SNDRV_SEQ_EVENT_LENGTH_FIXED;
        return ev->type != SNDRV_SEQ_EVENT_NONE;
    }

    spin_lock_irqsave(&dev->lock, flags);
    if ((c & 0x80) &&
        (c != MIDI_CMD_COMMON_SYSEX_END || dev->type != ST_SYSEX)) {
        /* new command */
        dev->buf[0] = c;
        if ((c & 0xf0) == 0xf0) /* system messages */
            dev->type = (c & 0x0f) + ST_SPECIAL;
        else
            dev->type = (c >> 4) & 0x07;
        dev->read = 1;
        dev->qlen = status_event[dev->type].qlen;
    } else {
        if (dev->qlen > 0) {
            /* rest of command */
            dev->buf[dev->read++] = c;
            if (dev->type != ST_SYSEX)
                dev->qlen--;
        } else {
            /* running status */
            dev->buf[1] = c;
            dev->qlen = status_event[dev->type].qlen - 1;
            dev->read = 2;
        }
    }
    if (dev->qlen == 0) {
        ev->type = status_event[dev->type].event;
        ev->flags &= ~SNDRV_SEQ_EVENT_LENGTH_MASK;
        ev->flags |= SNDRV_SEQ_EVENT_LENGTH_FIXED;
        if (status_event[dev->type].encode) /* set data values */
            status_event[dev->type].encode(dev, ev);
        if (dev->type >= ST_SPECIAL)
            dev->type = ST_INVALID;
        rc = 1;
    } else  if (dev->type == ST_SYSEX) {
        if (c == MIDI_CMD_COMMON_SYSEX_END ||
            dev->read >= dev->bufsize) {
            ev->flags &= ~SNDRV_SEQ_EVENT_LENGTH_MASK;
            ev->flags |= SNDRV_SEQ_EVENT_LENGTH_VARIABLE;
            ev->type = SNDRV_SEQ_EVENT_SYSEX;
            ev->data.ext.len = dev->read;
            ev->data.ext.ptr = dev->buf;
            if (c != MIDI_CMD_COMMON_SYSEX_END)
                dev->read = 0; /* continue to parse */
            else
                reset_encode(dev); /* all parsed */
            rc = 1;
        }
    }

    spin_unlock_irqrestore(&dev->lock, flags);
    return rc;
}

/* encode note event */
static void note_event(struct snd_midi_event *dev, struct snd_seq_event *ev)
{
    ev->data.note.channel = dev->buf[0] & 0x0f;
    ev->data.note.note = dev->buf[1];
    ev->data.note.velocity = dev->buf[2];
}

/* encode one parameter controls */
static void one_param_ctrl_event(struct snd_midi_event *dev, struct snd_seq_event *ev)
{
    ev->data.control.channel = dev->buf[0] & 0x0f;
    ev->data.control.value = dev->buf[1];
}

/* encode pitch wheel change */
static void pitchbend_ctrl_event(struct snd_midi_event *dev, struct snd_seq_event *ev)
{
    ev->data.control.channel = dev->buf[0] & 0x0f;
    ev->data.control.value = (int)dev->buf[2] * 128 + (int)dev->buf[1] - 8192;
}

/* encode midi control change */
static void two_param_ctrl_event(struct snd_midi_event *dev, struct snd_seq_event *ev)
{
    ev->data.control.channel = dev->buf[0] & 0x0f;
    ev->data.control.param = dev->buf[1];
    ev->data.control.value = dev->buf[2];
}

/* encode one parameter value*/
static void one_param_event(struct snd_midi_event *dev, struct snd_seq_event *ev)
{
    ev->data.control.value = dev->buf[1];
}

/* encode song position */
static void songpos_event(struct snd_midi_event *dev, struct snd_seq_event *ev)
{
    ev->data.control.value = (int)dev->buf[2] * 128 + (int)dev->buf[1];
}

/*
 * decode from a sequencer event to midi bytes
 * return the size of decoded midi events
 */
long snd_midi_event_decode(struct snd_midi_event *dev, unsigned char *buf, long count,
               struct snd_seq_event *ev)
{
    unsigned int cmd, type;

    if (ev->type == SNDRV_SEQ_EVENT_NONE)
        return -ENOENT;

    for (type = 0; type < ARRAY_SIZE(status_event); type++) {
        if (ev->type == status_event[type].event)
            goto __found;
    }
    for (type = 0; type < ARRAY_SIZE(extra_event); type++) {
        if (ev->type == extra_event[type].event)
            return extra_event[type].decode(dev, buf, count, ev);
    }
    return -ENOENT;

      __found:
    if (type >= ST_SPECIAL)
        cmd = 0xf0 + (type - ST_SPECIAL);
    else
        /* data.note.channel and data.control.channel is identical */
        cmd = 0x80 | (type << 4) | (ev->data.note.channel & 0x0f);


    if (cmd == MIDI_CMD_COMMON_SYSEX) {
        snd_midi_event_reset_decode(dev);
        return snd_seq_expand_var_event(ev, count, buf, 1, 0);
    } else {
        int qlen;
        unsigned char xbuf[4];
        unsigned long flags;

        spin_lock_irqsave(&dev->lock, flags);
        if ((cmd & 0xf0) == 0xf0 || dev->lastcmd != cmd || dev->nostat) {
            dev->lastcmd = cmd;
            spin_unlock_irqrestore(&dev->lock, flags);
            xbuf[0] = cmd;
            if (status_event[type].decode)
                status_event[type].decode(ev, xbuf + 1);
            qlen = status_event[type].qlen + 1;
        } else {
            spin_unlock_irqrestore(&dev->lock, flags);
            if (status_event[type].decode)
                status_event[type].decode(ev, xbuf + 0);
            qlen = status_event[type].qlen;
        }
        if (count < qlen)
            return -ENOMEM;
        memcpy(buf, xbuf, qlen);
        return qlen;
    }
}


/* decode note event */
static void note_decode(struct snd_seq_event *ev, unsigned char *buf)
{
    buf[0] = ev->data.note.note & 0x7f;
    buf[1] = ev->data.note.velocity & 0x7f;
}

/* decode one parameter controls */
static void one_param_decode(struct snd_seq_event *ev, unsigned char *buf)
{
    buf[0] = ev->data.control.value & 0x7f;
}

/* decode pitch wheel change */
static void pitchbend_decode(struct snd_seq_event *ev, unsigned char *buf)
{
    int value = ev->data.control.value + 8192;
    buf[0] = value & 0x7f;
    buf[1] = (value >> 7) & 0x7f;
}

/* decode midi control change */
static void two_param_decode(struct snd_seq_event *ev, unsigned char *buf)
{
    buf[0] = ev->data.control.param & 0x7f;
    buf[1] = ev->data.control.value & 0x7f;
}

/* decode song position */
static void songpos_decode(struct snd_seq_event *ev, unsigned char *buf)
{
    buf[0] = ev->data.control.value & 0x7f;
    buf[1] = (ev->data.control.value >> 7) & 0x7f;
}

/* decode 14bit control */
static int extra_decode_ctrl14(struct snd_midi_event *dev, unsigned char *buf,
                   int count, struct snd_seq_event *ev)
{
    unsigned char cmd;
    int idx = 0;

    cmd = MIDI_CMD_CONTROL|(ev->data.control.channel & 0x0f);
    if (ev->data.control.param < 0x20) {
        if (count < 4)
            return -ENOMEM;
        if (dev->nostat && count < 6)
            return -ENOMEM;
        if (cmd != dev->lastcmd || dev->nostat) {
            if (count < 5)
                return -ENOMEM;
            buf[idx++] = dev->lastcmd = cmd;
        }
        buf[idx++] = ev->data.control.param;
        buf[idx++] = (ev->data.control.value >> 7) & 0x7f;
        if (dev->nostat)
            buf[idx++] = cmd;
        buf[idx++] = ev->data.control.param + 0x20;
        buf[idx++] = ev->data.control.value & 0x7f;
    } else {
        if (count < 2)
            return -ENOMEM;
        if (cmd != dev->lastcmd || dev->nostat) {
            if (count < 3)
                return -ENOMEM;
            buf[idx++] = dev->lastcmd = cmd;
        }
        buf[idx++] = ev->data.control.param & 0x7f;
        buf[idx++] = ev->data.control.value & 0x7f;
    }
    return idx;
}

/* decode reg/nonreg param */
static int extra_decode_xrpn(struct snd_midi_event *dev, unsigned char *buf,
                 int count, struct snd_seq_event *ev)
{
    unsigned char cmd;
    char *cbytes;
    static char cbytes_nrpn[4] = { MIDI_CTL_NONREG_PARM_NUM_MSB,
                       MIDI_CTL_NONREG_PARM_NUM_LSB,
                       MIDI_CTL_MSB_DATA_ENTRY,
                       MIDI_CTL_LSB_DATA_ENTRY };
    static char cbytes_rpn[4] =  { MIDI_CTL_REGIST_PARM_NUM_MSB,
                       MIDI_CTL_REGIST_PARM_NUM_LSB,
                       MIDI_CTL_MSB_DATA_ENTRY,
                       MIDI_CTL_LSB_DATA_ENTRY };
    unsigned char bytes[4];
    int idx = 0, i;

    if (count < 8)
        return -ENOMEM;
    if (dev->nostat && count < 12)
        return -ENOMEM;
    cmd = MIDI_CMD_CONTROL|(ev->data.control.channel & 0x0f);
    bytes[0] = (ev->data.control.param & 0x3f80) >> 7;
    bytes[1] = ev->data.control.param & 0x007f;
    bytes[2] = (ev->data.control.value & 0x3f80) >> 7;
    bytes[3] = ev->data.control.value & 0x007f;
    if (cmd != dev->lastcmd && !dev->nostat) {
        if (count < 9)
            return -ENOMEM;
        buf[idx++] = dev->lastcmd = cmd;
    }
    cbytes = ev->type == SNDRV_SEQ_EVENT_NONREGPARAM ? cbytes_nrpn : cbytes_rpn;
    for (i = 0; i < 4; i++) {
        if (dev->nostat)
            buf[idx++] = dev->lastcmd = cmd;
        buf[idx++] = cbytes[i];
        buf[idx++] = bytes[i];
    }
    return idx;
}

/*
 *  exports
 */
 
EXPORT_SYMBOL(snd_midi_event_new);
EXPORT_SYMBOL(snd_midi_event_free);
EXPORT_SYMBOL(snd_midi_event_reset_encode);
EXPORT_SYMBOL(snd_midi_event_reset_decode);
EXPORT_SYMBOL(snd_midi_event_no_status);
EXPORT_SYMBOL(snd_midi_event_encode);
EXPORT_SYMBOL(snd_midi_event_encode_byte);
EXPORT_SYMBOL(snd_midi_event_decode);

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

static void __exit alsa_seq_midi_event_exit(void)
{
}

module_init(alsa_seq_midi_event_init)
module_exit(alsa_seq_midi_event_exit)