// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  MIDI byte <-> sequencer event coder
 *
 *  Copyright (C) 1998,99 Takashi Iwai <tiwai@suse.de>,
 *                        Jaroslav Kysela <perex@perex.cz>
 */

#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 <tiwai@suse.de>, Jaroslav Kysela <perex@perex.cz>");
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_obj(*dev);
        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;
}
EXPORT_SYMBOL(snd_midi_event_new);

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

/*
 * 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)
{
        guard(spinlock_irqsave)(&dev->lock);
        reset_encode(dev);
}
EXPORT_SYMBOL(snd_midi_event_reset_encode);

void snd_midi_event_reset_decode(struct snd_midi_event *dev)
{
        guard(spinlock_irqsave)(&dev->lock);
        dev->lastcmd = 0xff;
}
EXPORT_SYMBOL(snd_midi_event_reset_decode);

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

/*
 *  read one byte and encode to sequencer event:
 *  return true if MIDI bytes are encoded to an event
 *         false data is not finished
 */
bool snd_midi_event_encode_byte(struct snd_midi_event *dev, unsigned char c,
                                struct snd_seq_event *ev)
{
        bool rc = false;

        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;
        }

        guard(spinlock_irqsave)(&dev->lock);
        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 = true;
        } 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 = true;
                }
        }

        return rc;
}
EXPORT_SYMBOL(snd_midi_event_encode_byte);

/* 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;
        }
}
EXPORT_SYMBOL(snd_midi_event_decode);


/* 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;
        const char *cbytes;
        static const 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 const 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;
}