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0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  MIDI byte <-> sequencer event coder
0004  *
0005  *  Copyright (C) 1998,99 Takashi Iwai <tiwai@suse.de>,
0006  *                        Jaroslav Kysela <perex@perex.cz>
0007  */
0008 
0009 #include <linux/slab.h>
0010 #include <linux/errno.h>
0011 #include <linux/string.h>
0012 #include <linux/module.h>
0013 #include <sound/core.h>
0014 #include <sound/seq_kernel.h>
0015 #include <sound/seq_midi_event.h>
0016 #include <sound/asoundef.h>
0017 
0018 MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>, Jaroslav Kysela <perex@perex.cz>");
0019 MODULE_DESCRIPTION("MIDI byte <-> sequencer event coder");
0020 MODULE_LICENSE("GPL");
0021 
0022 /* event type, index into status_event[] */
0023 /* from 0 to 6 are normal commands (note off, on, etc.) for 0x9?-0xe? */
0024 #define ST_INVALID  7
0025 #define ST_SPECIAL  8
0026 #define ST_SYSEX    ST_SPECIAL
0027 /* from 8 to 15 are events for 0xf0-0xf7 */
0028 
0029 
0030 /*
0031  * prototypes
0032  */
0033 static void note_event(struct snd_midi_event *dev, struct snd_seq_event *ev);
0034 static void one_param_ctrl_event(struct snd_midi_event *dev, struct snd_seq_event *ev);
0035 static void pitchbend_ctrl_event(struct snd_midi_event *dev, struct snd_seq_event *ev);
0036 static void two_param_ctrl_event(struct snd_midi_event *dev, struct snd_seq_event *ev);
0037 static void one_param_event(struct snd_midi_event *dev, struct snd_seq_event *ev);
0038 static void songpos_event(struct snd_midi_event *dev, struct snd_seq_event *ev);
0039 static void note_decode(struct snd_seq_event *ev, unsigned char *buf);
0040 static void one_param_decode(struct snd_seq_event *ev, unsigned char *buf);
0041 static void pitchbend_decode(struct snd_seq_event *ev, unsigned char *buf);
0042 static void two_param_decode(struct snd_seq_event *ev, unsigned char *buf);
0043 static void songpos_decode(struct snd_seq_event *ev, unsigned char *buf);
0044 
0045 /*
0046  * event list
0047  */
0048 static struct status_event_list {
0049     int event;
0050     int qlen;
0051     void (*encode)(struct snd_midi_event *dev, struct snd_seq_event *ev);
0052     void (*decode)(struct snd_seq_event *ev, unsigned char *buf);
0053 } status_event[] = {
0054     /* 0x80 - 0xef */
0055     {SNDRV_SEQ_EVENT_NOTEOFF,    2, note_event, note_decode},
0056     {SNDRV_SEQ_EVENT_NOTEON,     2, note_event, note_decode},
0057     {SNDRV_SEQ_EVENT_KEYPRESS,   2, note_event, note_decode},
0058     {SNDRV_SEQ_EVENT_CONTROLLER,     2, two_param_ctrl_event, two_param_decode},
0059     {SNDRV_SEQ_EVENT_PGMCHANGE,  1, one_param_ctrl_event, one_param_decode},
0060     {SNDRV_SEQ_EVENT_CHANPRESS,  1, one_param_ctrl_event, one_param_decode},
0061     {SNDRV_SEQ_EVENT_PITCHBEND,  2, pitchbend_ctrl_event, pitchbend_decode},
0062     /* invalid */
0063     {SNDRV_SEQ_EVENT_NONE,      -1, NULL, NULL},
0064     /* 0xf0 - 0xff */
0065     {SNDRV_SEQ_EVENT_SYSEX,      1, NULL, NULL}, /* sysex: 0xf0 */
0066     {SNDRV_SEQ_EVENT_QFRAME,     1, one_param_event, one_param_decode}, /* 0xf1 */
0067     {SNDRV_SEQ_EVENT_SONGPOS,    2, songpos_event, songpos_decode}, /* 0xf2 */
0068     {SNDRV_SEQ_EVENT_SONGSEL,    1, one_param_event, one_param_decode}, /* 0xf3 */
0069     {SNDRV_SEQ_EVENT_NONE,      -1, NULL, NULL}, /* 0xf4 */
0070     {SNDRV_SEQ_EVENT_NONE,      -1, NULL, NULL}, /* 0xf5 */
0071     {SNDRV_SEQ_EVENT_TUNE_REQUEST,   0, NULL, NULL}, /* 0xf6 */
0072     {SNDRV_SEQ_EVENT_NONE,      -1, NULL, NULL}, /* 0xf7 */
0073     {SNDRV_SEQ_EVENT_CLOCK,      0, NULL, NULL}, /* 0xf8 */
0074     {SNDRV_SEQ_EVENT_NONE,      -1, NULL, NULL}, /* 0xf9 */
0075     {SNDRV_SEQ_EVENT_START,      0, NULL, NULL}, /* 0xfa */
0076     {SNDRV_SEQ_EVENT_CONTINUE,   0, NULL, NULL}, /* 0xfb */
0077     {SNDRV_SEQ_EVENT_STOP,       0, NULL, NULL}, /* 0xfc */
0078     {SNDRV_SEQ_EVENT_NONE,      -1, NULL, NULL}, /* 0xfd */
0079     {SNDRV_SEQ_EVENT_SENSING,    0, NULL, NULL}, /* 0xfe */
0080     {SNDRV_SEQ_EVENT_RESET,      0, NULL, NULL}, /* 0xff */
0081 };
0082 
0083 static int extra_decode_ctrl14(struct snd_midi_event *dev, unsigned char *buf, int len,
0084                    struct snd_seq_event *ev);
0085 static int extra_decode_xrpn(struct snd_midi_event *dev, unsigned char *buf, int count,
0086                  struct snd_seq_event *ev);
0087 
0088 static struct extra_event_list {
0089     int event;
0090     int (*decode)(struct snd_midi_event *dev, unsigned char *buf, int len,
0091               struct snd_seq_event *ev);
0092 } extra_event[] = {
0093     {SNDRV_SEQ_EVENT_CONTROL14, extra_decode_ctrl14},
0094     {SNDRV_SEQ_EVENT_NONREGPARAM, extra_decode_xrpn},
0095     {SNDRV_SEQ_EVENT_REGPARAM, extra_decode_xrpn},
0096 };
0097 
0098 /*
0099  *  new/delete record
0100  */
0101 
0102 int snd_midi_event_new(int bufsize, struct snd_midi_event **rdev)
0103 {
0104     struct snd_midi_event *dev;
0105 
0106     *rdev = NULL;
0107     dev = kzalloc(sizeof(*dev), GFP_KERNEL);
0108     if (dev == NULL)
0109         return -ENOMEM;
0110     if (bufsize > 0) {
0111         dev->buf = kmalloc(bufsize, GFP_KERNEL);
0112         if (dev->buf == NULL) {
0113             kfree(dev);
0114             return -ENOMEM;
0115         }
0116     }
0117     dev->bufsize = bufsize;
0118     dev->lastcmd = 0xff;
0119     dev->type = ST_INVALID;
0120     spin_lock_init(&dev->lock);
0121     *rdev = dev;
0122     return 0;
0123 }
0124 EXPORT_SYMBOL(snd_midi_event_new);
0125 
0126 void snd_midi_event_free(struct snd_midi_event *dev)
0127 {
0128     if (dev != NULL) {
0129         kfree(dev->buf);
0130         kfree(dev);
0131     }
0132 }
0133 EXPORT_SYMBOL(snd_midi_event_free);
0134 
0135 /*
0136  * initialize record
0137  */
0138 static inline void reset_encode(struct snd_midi_event *dev)
0139 {
0140     dev->read = 0;
0141     dev->qlen = 0;
0142     dev->type = ST_INVALID;
0143 }
0144 
0145 void snd_midi_event_reset_encode(struct snd_midi_event *dev)
0146 {
0147     unsigned long flags;
0148 
0149     spin_lock_irqsave(&dev->lock, flags);
0150     reset_encode(dev);
0151     spin_unlock_irqrestore(&dev->lock, flags);
0152 }
0153 EXPORT_SYMBOL(snd_midi_event_reset_encode);
0154 
0155 void snd_midi_event_reset_decode(struct snd_midi_event *dev)
0156 {
0157     unsigned long flags;
0158 
0159     spin_lock_irqsave(&dev->lock, flags);
0160     dev->lastcmd = 0xff;
0161     spin_unlock_irqrestore(&dev->lock, flags);
0162 }
0163 EXPORT_SYMBOL(snd_midi_event_reset_decode);
0164 
0165 void snd_midi_event_no_status(struct snd_midi_event *dev, int on)
0166 {
0167     dev->nostat = on ? 1 : 0;
0168 }
0169 EXPORT_SYMBOL(snd_midi_event_no_status);
0170 
0171 /*
0172  *  read one byte and encode to sequencer event:
0173  *  return true if MIDI bytes are encoded to an event
0174  *         false data is not finished
0175  */
0176 bool snd_midi_event_encode_byte(struct snd_midi_event *dev, unsigned char c,
0177                 struct snd_seq_event *ev)
0178 {
0179     bool rc = false;
0180     unsigned long flags;
0181 
0182     if (c >= MIDI_CMD_COMMON_CLOCK) {
0183         /* real-time event */
0184         ev->type = status_event[ST_SPECIAL + c - 0xf0].event;
0185         ev->flags &= ~SNDRV_SEQ_EVENT_LENGTH_MASK;
0186         ev->flags |= SNDRV_SEQ_EVENT_LENGTH_FIXED;
0187         return ev->type != SNDRV_SEQ_EVENT_NONE;
0188     }
0189 
0190     spin_lock_irqsave(&dev->lock, flags);
0191     if ((c & 0x80) &&
0192         (c != MIDI_CMD_COMMON_SYSEX_END || dev->type != ST_SYSEX)) {
0193         /* new command */
0194         dev->buf[0] = c;
0195         if ((c & 0xf0) == 0xf0) /* system messages */
0196             dev->type = (c & 0x0f) + ST_SPECIAL;
0197         else
0198             dev->type = (c >> 4) & 0x07;
0199         dev->read = 1;
0200         dev->qlen = status_event[dev->type].qlen;
0201     } else {
0202         if (dev->qlen > 0) {
0203             /* rest of command */
0204             dev->buf[dev->read++] = c;
0205             if (dev->type != ST_SYSEX)
0206                 dev->qlen--;
0207         } else {
0208             /* running status */
0209             dev->buf[1] = c;
0210             dev->qlen = status_event[dev->type].qlen - 1;
0211             dev->read = 2;
0212         }
0213     }
0214     if (dev->qlen == 0) {
0215         ev->type = status_event[dev->type].event;
0216         ev->flags &= ~SNDRV_SEQ_EVENT_LENGTH_MASK;
0217         ev->flags |= SNDRV_SEQ_EVENT_LENGTH_FIXED;
0218         if (status_event[dev->type].encode) /* set data values */
0219             status_event[dev->type].encode(dev, ev);
0220         if (dev->type >= ST_SPECIAL)
0221             dev->type = ST_INVALID;
0222         rc = true;
0223     } else  if (dev->type == ST_SYSEX) {
0224         if (c == MIDI_CMD_COMMON_SYSEX_END ||
0225             dev->read >= dev->bufsize) {
0226             ev->flags &= ~SNDRV_SEQ_EVENT_LENGTH_MASK;
0227             ev->flags |= SNDRV_SEQ_EVENT_LENGTH_VARIABLE;
0228             ev->type = SNDRV_SEQ_EVENT_SYSEX;
0229             ev->data.ext.len = dev->read;
0230             ev->data.ext.ptr = dev->buf;
0231             if (c != MIDI_CMD_COMMON_SYSEX_END)
0232                 dev->read = 0; /* continue to parse */
0233             else
0234                 reset_encode(dev); /* all parsed */
0235             rc = true;
0236         }
0237     }
0238 
0239     spin_unlock_irqrestore(&dev->lock, flags);
0240     return rc;
0241 }
0242 EXPORT_SYMBOL(snd_midi_event_encode_byte);
0243 
0244 /* encode note event */
0245 static void note_event(struct snd_midi_event *dev, struct snd_seq_event *ev)
0246 {
0247     ev->data.note.channel = dev->buf[0] & 0x0f;
0248     ev->data.note.note = dev->buf[1];
0249     ev->data.note.velocity = dev->buf[2];
0250 }
0251 
0252 /* encode one parameter controls */
0253 static void one_param_ctrl_event(struct snd_midi_event *dev, struct snd_seq_event *ev)
0254 {
0255     ev->data.control.channel = dev->buf[0] & 0x0f;
0256     ev->data.control.value = dev->buf[1];
0257 }
0258 
0259 /* encode pitch wheel change */
0260 static void pitchbend_ctrl_event(struct snd_midi_event *dev, struct snd_seq_event *ev)
0261 {
0262     ev->data.control.channel = dev->buf[0] & 0x0f;
0263     ev->data.control.value = (int)dev->buf[2] * 128 + (int)dev->buf[1] - 8192;
0264 }
0265 
0266 /* encode midi control change */
0267 static void two_param_ctrl_event(struct snd_midi_event *dev, struct snd_seq_event *ev)
0268 {
0269     ev->data.control.channel = dev->buf[0] & 0x0f;
0270     ev->data.control.param = dev->buf[1];
0271     ev->data.control.value = dev->buf[2];
0272 }
0273 
0274 /* encode one parameter value*/
0275 static void one_param_event(struct snd_midi_event *dev, struct snd_seq_event *ev)
0276 {
0277     ev->data.control.value = dev->buf[1];
0278 }
0279 
0280 /* encode song position */
0281 static void songpos_event(struct snd_midi_event *dev, struct snd_seq_event *ev)
0282 {
0283     ev->data.control.value = (int)dev->buf[2] * 128 + (int)dev->buf[1];
0284 }
0285 
0286 /*
0287  * decode from a sequencer event to midi bytes
0288  * return the size of decoded midi events
0289  */
0290 long snd_midi_event_decode(struct snd_midi_event *dev, unsigned char *buf, long count,
0291                struct snd_seq_event *ev)
0292 {
0293     unsigned int cmd, type;
0294 
0295     if (ev->type == SNDRV_SEQ_EVENT_NONE)
0296         return -ENOENT;
0297 
0298     for (type = 0; type < ARRAY_SIZE(status_event); type++) {
0299         if (ev->type == status_event[type].event)
0300             goto __found;
0301     }
0302     for (type = 0; type < ARRAY_SIZE(extra_event); type++) {
0303         if (ev->type == extra_event[type].event)
0304             return extra_event[type].decode(dev, buf, count, ev);
0305     }
0306     return -ENOENT;
0307 
0308       __found:
0309     if (type >= ST_SPECIAL)
0310         cmd = 0xf0 + (type - ST_SPECIAL);
0311     else
0312         /* data.note.channel and data.control.channel is identical */
0313         cmd = 0x80 | (type << 4) | (ev->data.note.channel & 0x0f);
0314 
0315 
0316     if (cmd == MIDI_CMD_COMMON_SYSEX) {
0317         snd_midi_event_reset_decode(dev);
0318         return snd_seq_expand_var_event(ev, count, buf, 1, 0);
0319     } else {
0320         int qlen;
0321         unsigned char xbuf[4];
0322         unsigned long flags;
0323 
0324         spin_lock_irqsave(&dev->lock, flags);
0325         if ((cmd & 0xf0) == 0xf0 || dev->lastcmd != cmd || dev->nostat) {
0326             dev->lastcmd = cmd;
0327             spin_unlock_irqrestore(&dev->lock, flags);
0328             xbuf[0] = cmd;
0329             if (status_event[type].decode)
0330                 status_event[type].decode(ev, xbuf + 1);
0331             qlen = status_event[type].qlen + 1;
0332         } else {
0333             spin_unlock_irqrestore(&dev->lock, flags);
0334             if (status_event[type].decode)
0335                 status_event[type].decode(ev, xbuf + 0);
0336             qlen = status_event[type].qlen;
0337         }
0338         if (count < qlen)
0339             return -ENOMEM;
0340         memcpy(buf, xbuf, qlen);
0341         return qlen;
0342     }
0343 }
0344 EXPORT_SYMBOL(snd_midi_event_decode);
0345 
0346 
0347 /* decode note event */
0348 static void note_decode(struct snd_seq_event *ev, unsigned char *buf)
0349 {
0350     buf[0] = ev->data.note.note & 0x7f;
0351     buf[1] = ev->data.note.velocity & 0x7f;
0352 }
0353 
0354 /* decode one parameter controls */
0355 static void one_param_decode(struct snd_seq_event *ev, unsigned char *buf)
0356 {
0357     buf[0] = ev->data.control.value & 0x7f;
0358 }
0359 
0360 /* decode pitch wheel change */
0361 static void pitchbend_decode(struct snd_seq_event *ev, unsigned char *buf)
0362 {
0363     int value = ev->data.control.value + 8192;
0364     buf[0] = value & 0x7f;
0365     buf[1] = (value >> 7) & 0x7f;
0366 }
0367 
0368 /* decode midi control change */
0369 static void two_param_decode(struct snd_seq_event *ev, unsigned char *buf)
0370 {
0371     buf[0] = ev->data.control.param & 0x7f;
0372     buf[1] = ev->data.control.value & 0x7f;
0373 }
0374 
0375 /* decode song position */
0376 static void songpos_decode(struct snd_seq_event *ev, unsigned char *buf)
0377 {
0378     buf[0] = ev->data.control.value & 0x7f;
0379     buf[1] = (ev->data.control.value >> 7) & 0x7f;
0380 }
0381 
0382 /* decode 14bit control */
0383 static int extra_decode_ctrl14(struct snd_midi_event *dev, unsigned char *buf,
0384                    int count, struct snd_seq_event *ev)
0385 {
0386     unsigned char cmd;
0387     int idx = 0;
0388 
0389     cmd = MIDI_CMD_CONTROL|(ev->data.control.channel & 0x0f);
0390     if (ev->data.control.param < 0x20) {
0391         if (count < 4)
0392             return -ENOMEM;
0393         if (dev->nostat && count < 6)
0394             return -ENOMEM;
0395         if (cmd != dev->lastcmd || dev->nostat) {
0396             if (count < 5)
0397                 return -ENOMEM;
0398             buf[idx++] = dev->lastcmd = cmd;
0399         }
0400         buf[idx++] = ev->data.control.param;
0401         buf[idx++] = (ev->data.control.value >> 7) & 0x7f;
0402         if (dev->nostat)
0403             buf[idx++] = cmd;
0404         buf[idx++] = ev->data.control.param + 0x20;
0405         buf[idx++] = ev->data.control.value & 0x7f;
0406     } else {
0407         if (count < 2)
0408             return -ENOMEM;
0409         if (cmd != dev->lastcmd || dev->nostat) {
0410             if (count < 3)
0411                 return -ENOMEM;
0412             buf[idx++] = dev->lastcmd = cmd;
0413         }
0414         buf[idx++] = ev->data.control.param & 0x7f;
0415         buf[idx++] = ev->data.control.value & 0x7f;
0416     }
0417     return idx;
0418 }
0419 
0420 /* decode reg/nonreg param */
0421 static int extra_decode_xrpn(struct snd_midi_event *dev, unsigned char *buf,
0422                  int count, struct snd_seq_event *ev)
0423 {
0424     unsigned char cmd;
0425     const char *cbytes;
0426     static const char cbytes_nrpn[4] = { MIDI_CTL_NONREG_PARM_NUM_MSB,
0427                        MIDI_CTL_NONREG_PARM_NUM_LSB,
0428                        MIDI_CTL_MSB_DATA_ENTRY,
0429                        MIDI_CTL_LSB_DATA_ENTRY };
0430     static const char cbytes_rpn[4] =  { MIDI_CTL_REGIST_PARM_NUM_MSB,
0431                        MIDI_CTL_REGIST_PARM_NUM_LSB,
0432                        MIDI_CTL_MSB_DATA_ENTRY,
0433                        MIDI_CTL_LSB_DATA_ENTRY };
0434     unsigned char bytes[4];
0435     int idx = 0, i;
0436 
0437     if (count < 8)
0438         return -ENOMEM;
0439     if (dev->nostat && count < 12)
0440         return -ENOMEM;
0441     cmd = MIDI_CMD_CONTROL|(ev->data.control.channel & 0x0f);
0442     bytes[0] = (ev->data.control.param & 0x3f80) >> 7;
0443     bytes[1] = ev->data.control.param & 0x007f;
0444     bytes[2] = (ev->data.control.value & 0x3f80) >> 7;
0445     bytes[3] = ev->data.control.value & 0x007f;
0446     if (cmd != dev->lastcmd && !dev->nostat) {
0447         if (count < 9)
0448             return -ENOMEM;
0449         buf[idx++] = dev->lastcmd = cmd;
0450     }
0451     cbytes = ev->type == SNDRV_SEQ_EVENT_NONREGPARAM ? cbytes_nrpn : cbytes_rpn;
0452     for (i = 0; i < 4; i++) {
0453         if (dev->nostat)
0454             buf[idx++] = dev->lastcmd = cmd;
0455         buf[idx++] = cbytes[i];
0456         buf[idx++] = bytes[i];
0457     }
0458     return idx;
0459 }
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