sound/oss/midibuf.c - kernel/msm-4.9 - Gitiles

 /*
  * sound/midibuf.c
  *
  * Device file manager for /dev/midi#
  */
 /*
  * Copyright (C) by Hannu Savolainen 1993-1997
  *
  * OSS/Free for Linux is distributed under the GNU GENERAL PUBLIC LICENSE (GPL)
  * Version 2 (June 1991). See the "COPYING" file distributed with this software
  * for more info.
  */
 /*
  * Thomas Sailer   : ioctl code reworked (vmalloc/vfree removed)
  */
 #include <linux/stddef.h>
 #include <linux/kmod.h>
 #include <linux/spinlock.h>
 #define MIDIBUF_C

 #include "sound_config.h"


 /*
  * Don't make MAX_QUEUE_SIZE larger than 4000
  */

 #define MAX_QUEUE_SIZE	4000

 static wait_queue_head_t midi_sleeper[MAX_MIDI_DEV];
 static wait_queue_head_t input_sleeper[MAX_MIDI_DEV];

 struct midi_buf
 {
 	int len, head, tail;
 	unsigned char queue[MAX_QUEUE_SIZE];
 };

 struct midi_parms
 {
 	long prech_timeout;	/*
 				 * Timeout before the first ch
 				 */
 };

 static struct midi_buf *midi_out_buf[MAX_MIDI_DEV] = {NULL};
 static struct midi_buf *midi_in_buf[MAX_MIDI_DEV] = {NULL};
 static struct midi_parms parms[MAX_MIDI_DEV];

 static void midi_poll(unsigned long dummy);


 static struct timer_list poll_timer = TIMER_INITIALIZER(midi_poll, 0, 0);

 static volatile int open_devs;
 static DEFINE_SPINLOCK(lock);

 #define DATA_AVAIL(q) (q->len)
 #define SPACE_AVAIL(q) (MAX_QUEUE_SIZE - q->len)

 #define QUEUE_BYTE(q, data) \
 	if (SPACE_AVAIL(q)) \
 	{ \
 	  unsigned long flags; \
 	  spin_lock_irqsave(&lock, flags); \
 	  q->queue[q->tail] = (data); \
 	  q->len++; q->tail = (q->tail+1) % MAX_QUEUE_SIZE; \
 	  spin_unlock_irqrestore(&lock, flags); \
 	}

 #define REMOVE_BYTE(q, data) \
 	if (DATA_AVAIL(q)) \
 	{ \
 	  unsigned long flags; \
 	  spin_lock_irqsave(&lock, flags); \
 	  data = q->queue[q->head]; \
 	  q->len--; q->head = (q->head+1) % MAX_QUEUE_SIZE; \
 	  spin_unlock_irqrestore(&lock, flags); \
 	}

 static void drain_midi_queue(int dev)
 {

 	/*
 	 * Give the Midi driver time to drain its output queues
 	 */

 	if (midi_devs[dev]->buffer_status != NULL)
 		while (!signal_pending(current) && midi_devs[dev]->buffer_status(dev))
 			interruptible_sleep_on_timeout(&midi_sleeper[dev],
 						       HZ/10);
 }

 static void midi_input_intr(int dev, unsigned char data)
 {
 	if (midi_in_buf[dev] == NULL)
 		return;

 	if (data == 0xfe)	/*
 				 * Active sensing
 				 */
 		return;		/*
 				 * Ignore
 				 */

 	if (SPACE_AVAIL(midi_in_buf[dev])) {
 		QUEUE_BYTE(midi_in_buf[dev], data);
 		wake_up(&input_sleeper[dev]);
 	}
 }

 static void midi_output_intr(int dev)
 {
 	/*
 	 * Currently NOP
 	 */
 }

 static void midi_poll(unsigned long dummy)
 {
 	unsigned long   flags;
 	int             dev;

 	spin_lock_irqsave(&lock, flags);
 	if (open_devs)
 	{
 		for (dev = 0; dev < num_midis; dev++)
 			if (midi_devs[dev] != NULL && midi_out_buf[dev] != NULL)
 			{
 				int ok = 1;

 				while (DATA_AVAIL(midi_out_buf[dev]) && ok)
 				{
 					int c = midi_out_buf[dev]->queue[midi_out_buf[dev]->head];

 					spin_unlock_irqrestore(&lock,flags);/* Give some time to others */
 					ok = midi_devs[dev]->outputc(dev, c);
 					spin_lock_irqsave(&lock, flags);
 					midi_out_buf[dev]->head = (midi_out_buf[dev]->head + 1) % MAX_QUEUE_SIZE;
 					midi_out_buf[dev]->len--;
 				}

 				if (DATA_AVAIL(midi_out_buf[dev]) < 100)
 					wake_up(&midi_sleeper[dev]);
 			}
 		poll_timer.expires = (1) + jiffies;
 		add_timer(&poll_timer);
 		/*
 		 * Come back later
 		 */
 	}
 	spin_unlock_irqrestore(&lock, flags);
 }

 int MIDIbuf_open(int dev, struct file *file)
 {
 	int mode, err;

 	dev = dev >> 4;
 	mode = translate_mode(file);

 	if (num_midis > MAX_MIDI_DEV)
 	{
 		printk(KERN_ERR "midi: Too many midi interfaces\n");
 		num_midis = MAX_MIDI_DEV;
 	}
 	if (dev < 0 || dev >= num_midis || midi_devs[dev] == NULL)
 		  return -ENXIO;
 	/*
 	 *    Interrupts disabled. Be careful
 	 */

 	module_put(midi_devs[dev]->owner);

 	if ((err = midi_devs[dev]->open(dev, mode,
 				 midi_input_intr, midi_output_intr)) < 0)
 		return err;

 	parms[dev].prech_timeout = MAX_SCHEDULE_TIMEOUT;
 	midi_in_buf[dev] = (struct midi_buf *) vmalloc(sizeof(struct midi_buf));

 	if (midi_in_buf[dev] == NULL)
 	{
 		printk(KERN_WARNING "midi: Can't allocate buffer\n");
 		midi_devs[dev]->close(dev);
 		return -EIO;
 	}
 	midi_in_buf[dev]->len = midi_in_buf[dev]->head = midi_in_buf[dev]->tail = 0;

 	midi_out_buf[dev] = (struct midi_buf *) vmalloc(sizeof(struct midi_buf));

 	if (midi_out_buf[dev] == NULL)
 	{
 		printk(KERN_WARNING "midi: Can't allocate buffer\n");
 		midi_devs[dev]->close(dev);
 		vfree(midi_in_buf[dev]);
 		midi_in_buf[dev] = NULL;
 		return -EIO;
 	}
 	midi_out_buf[dev]->len = midi_out_buf[dev]->head = midi_out_buf[dev]->tail = 0;
 	open_devs++;

 	init_waitqueue_head(&midi_sleeper[dev]);
 	init_waitqueue_head(&input_sleeper[dev]);

 	if (open_devs < 2)	/* This was first open */
 	{
 		poll_timer.expires = 1 + jiffies;
 		add_timer(&poll_timer);	/* Start polling */
 	}
 	return err;
 }

 void MIDIbuf_release(int dev, struct file *file)
 {
 	int mode;

 	dev = dev >> 4;
 	mode = translate_mode(file);

 	if (dev < 0 || dev >= num_midis || midi_devs[dev] == NULL)
 		return;

 	/*
 	 * Wait until the queue is empty
 	 */

 	if (mode != OPEN_READ)
 	{
 		midi_devs[dev]->outputc(dev, 0xfe);	/*
 							   * Active sensing to shut the
 							   * devices
 							 */

 		while (!signal_pending(current) && DATA_AVAIL(midi_out_buf[dev]))
 			  interruptible_sleep_on(&midi_sleeper[dev]);
 		/*
 		 *	Sync
 		 */

 		drain_midi_queue(dev);	/*
 					 * Ensure the output queues are empty
 					 */
 	}

 	midi_devs[dev]->close(dev);

 	open_devs--;
 	if (open_devs == 0)
 		del_timer_sync(&poll_timer);
 	vfree(midi_in_buf[dev]);
 	vfree(midi_out_buf[dev]);
 	midi_in_buf[dev] = NULL;
 	midi_out_buf[dev] = NULL;

 	module_put(midi_devs[dev]->owner);
 }

 int MIDIbuf_write(int dev, struct file *file, const char __user *buf, int count)
 {
 	int c, n, i;
 	unsigned char tmp_data;

 	dev = dev >> 4;

 	if (!count)
 		return 0;

 	c = 0;

 	while (c < count)
 	{
 		n = SPACE_AVAIL(midi_out_buf[dev]);

 		if (n == 0) {	/*
 				 * No space just now.
 				 */

 			if (file->f_flags & O_NONBLOCK) {
 				c = -EAGAIN;
 				goto out;
 			}

 			interruptible_sleep_on(&midi_sleeper[dev]);
 			if (signal_pending(current))
 			{
 				c = -EINTR;
 				goto out;
 			}
 			n = SPACE_AVAIL(midi_out_buf[dev]);
 		}
 		if (n > (count - c))
 			n = count - c;

 		for (i = 0; i < n; i++)
 		{
 			/* BROKE BROKE BROKE - CANT DO THIS WITH CLI !! */
 			/* yes, think the same, so I removed the cli() brackets
 				QUEUE_BYTE is protected against interrupts */
 			if (copy_from_user((char *) &tmp_data, &(buf)[c], 1)) {
 				c = -EFAULT;
 				goto out;
 			}
 			QUEUE_BYTE(midi_out_buf[dev], tmp_data);
 			c++;
 		}
 	}
 out:
 	return c;
 }


 int MIDIbuf_read(int dev, struct file *file, char __user *buf, int count)
 {
 	int n, c = 0;
 	unsigned char tmp_data;

 	dev = dev >> 4;

 	if (!DATA_AVAIL(midi_in_buf[dev])) {	/*
 						 * No data yet, wait
 						 */
  		if (file->f_flags & O_NONBLOCK) {
  			c = -EAGAIN;
 			goto out;
  		}
 		interruptible_sleep_on_timeout(&input_sleeper[dev],
 					       parms[dev].prech_timeout);

 		if (signal_pending(current))
 			c = -EINTR;	/* The user is getting restless */
 	}
 	if (c == 0 && DATA_AVAIL(midi_in_buf[dev]))	/*
 							 * Got some bytes
 							 */
 	{
 		n = DATA_AVAIL(midi_in_buf[dev]);
 		if (n > count)
 			n = count;
 		c = 0;

 		while (c < n)
 		{
 			char *fixit;
 			REMOVE_BYTE(midi_in_buf[dev], tmp_data);
 			fixit = (char *) &tmp_data;
 			/* BROKE BROKE BROKE */
 			/* yes removed the cli() brackets again
 			 should q->len,tail&head be atomic_t? */
 			if (copy_to_user(&(buf)[c], fixit, 1)) {
 				c = -EFAULT;
 				goto out;
 			}
 			c++;
 		}
 	}
 out:
 	return c;
 }

 int MIDIbuf_ioctl(int dev, struct file *file,
 		  unsigned int cmd, void __user *arg)
 {
 	int val;

 	dev = dev >> 4;

 	if (((cmd >> 8) & 0xff) == 'C')
 	{
 		if (midi_devs[dev]->coproc)	/* Coprocessor ioctl */
 			return midi_devs[dev]->coproc->ioctl(midi_devs[dev]->coproc->devc, cmd, arg, 0);
 /*		printk("/dev/midi%d: No coprocessor for this device\n", dev);*/
 		return -ENXIO;
 	}
 	else
 	{
 		switch (cmd)
 		{
 			case SNDCTL_MIDI_PRETIME:
 				if (get_user(val, (int __user *)arg))
 					return -EFAULT;
 				if (val < 0)
 					val = 0;
 				val = (HZ * val) / 10;
 				parms[dev].prech_timeout = val;
 				return put_user(val, (int __user *)arg);

 			default:
 				if (!midi_devs[dev]->ioctl)
 					return -EINVAL;
 				return midi_devs[dev]->ioctl(dev, cmd, arg);
 		}
 	}
 }

 /* No kernel lock - fine */
 unsigned int MIDIbuf_poll(int dev, struct file *file, poll_table * wait)
 {
 	unsigned int mask = 0;

 	dev = dev >> 4;

 	/* input */
 	poll_wait(file, &input_sleeper[dev], wait);
 	if (DATA_AVAIL(midi_in_buf[dev]))
 		mask |= POLLIN | POLLRDNORM;

 	/* output */
 	poll_wait(file, &midi_sleeper[dev], wait);
 	if (!SPACE_AVAIL(midi_out_buf[dev]))
 		mask |= POLLOUT | POLLWRNORM;

 	return mask;
 }


 void MIDIbuf_init(void)
 {
 	/* drag in midi_syms.o */
 	{
 		extern char midi_syms_symbol;
 		midi_syms_symbol = 0;
 	}
 }

 int MIDIbuf_avail(int dev)
 {
 	if (midi_in_buf[dev])
 		return DATA_AVAIL (midi_in_buf[dev]);
 	return 0;
 }
	/*
	* sound/midibuf.c
	*
	* Device file manager for /dev/midi#
	*/
	/*
	* Copyright (C) by Hannu Savolainen 1993-1997
	*
	* OSS/Free for Linux is distributed under the GNU GENERAL PUBLIC LICENSE (GPL)
	* Version 2 (June 1991). See the "COPYING" file distributed with this software
	* for more info.
	*/
	/*
	* Thomas Sailer : ioctl code reworked (vmalloc/vfree removed)
	*/
	#include <linux/stddef.h>
	#include <linux/kmod.h>
	#include <linux/spinlock.h>
	#define MIDIBUF_C

	#include "sound_config.h"


	/*
	* Don't make MAX_QUEUE_SIZE larger than 4000
	*/

	#define MAX_QUEUE_SIZE 4000

	static wait_queue_head_t midi_sleeper[MAX_MIDI_DEV];
	static wait_queue_head_t input_sleeper[MAX_MIDI_DEV];

	struct midi_buf
	{
	int len, head, tail;
	unsigned char queue[MAX_QUEUE_SIZE];
	};

	struct midi_parms
	{
	long prech_timeout; /*
	* Timeout before the first ch
	*/
	};

	static struct midi_buf *midi_out_buf[MAX_MIDI_DEV] = {NULL};
	static struct midi_buf *midi_in_buf[MAX_MIDI_DEV] = {NULL};
	static struct midi_parms parms[MAX_MIDI_DEV];

	static void midi_poll(unsigned long dummy);


	static struct timer_list poll_timer = TIMER_INITIALIZER(midi_poll, 0, 0);

	static volatile int open_devs;
	static DEFINE_SPINLOCK(lock);

	#define DATA_AVAIL(q) (q->len)
	#define SPACE_AVAIL(q) (MAX_QUEUE_SIZE - q->len)

	#define QUEUE_BYTE(q, data) \
	if (SPACE_AVAIL(q)) \
	{ \
	unsigned long flags; \
	spin_lock_irqsave(&lock, flags); \
	q->queue[q->tail] = (data); \
	q->len++; q->tail = (q->tail+1) % MAX_QUEUE_SIZE; \
	spin_unlock_irqrestore(&lock, flags); \
	}

	#define REMOVE_BYTE(q, data) \
	if (DATA_AVAIL(q)) \
	{ \
	unsigned long flags; \
	spin_lock_irqsave(&lock, flags); \
	data = q->queue[q->head]; \
	q->len--; q->head = (q->head+1) % MAX_QUEUE_SIZE; \
	spin_unlock_irqrestore(&lock, flags); \
	}

	static void drain_midi_queue(int dev)
	{

	/*
	* Give the Midi driver time to drain its output queues
	*/

	if (midi_devs[dev]->buffer_status != NULL)
	while (!signal_pending(current) && midi_devs[dev]->buffer_status(dev))
	interruptible_sleep_on_timeout(&midi_sleeper[dev],
	HZ/10);
	}

	static void midi_input_intr(int dev, unsigned char data)
	{
	if (midi_in_buf[dev] == NULL)
	return;

	if (data == 0xfe) /*
	* Active sensing
	*/
	return; /*
	* Ignore
	*/

	if (SPACE_AVAIL(midi_in_buf[dev])) {
	QUEUE_BYTE(midi_in_buf[dev], data);
	wake_up(&input_sleeper[dev]);
	}
	}

	static void midi_output_intr(int dev)
	{
	/*
	* Currently NOP
	*/
	}

	static void midi_poll(unsigned long dummy)
	{
	unsigned long flags;
	int dev;

	spin_lock_irqsave(&lock, flags);
	if (open_devs)
	{
	for (dev = 0; dev < num_midis; dev++)
	if (midi_devs[dev] != NULL && midi_out_buf[dev] != NULL)
	{
	int ok = 1;

	while (DATA_AVAIL(midi_out_buf[dev]) && ok)
	{
	int c = midi_out_buf[dev]->queue[midi_out_buf[dev]->head];

	spin_unlock_irqrestore(&lock,flags);/* Give some time to others */
	ok = midi_devs[dev]->outputc(dev, c);
	spin_lock_irqsave(&lock, flags);
	midi_out_buf[dev]->head = (midi_out_buf[dev]->head + 1) % MAX_QUEUE_SIZE;
	midi_out_buf[dev]->len--;
	}

	if (DATA_AVAIL(midi_out_buf[dev]) < 100)
	wake_up(&midi_sleeper[dev]);
	}
	poll_timer.expires = (1) + jiffies;
	add_timer(&poll_timer);
	/*
	* Come back later
	*/
	}
	spin_unlock_irqrestore(&lock, flags);
	}

	int MIDIbuf_open(int dev, struct file *file)
	{
	int mode, err;

	dev = dev >> 4;
	mode = translate_mode(file);

	if (num_midis > MAX_MIDI_DEV)
	{
	printk(KERN_ERR "midi: Too many midi interfaces\n");
	num_midis = MAX_MIDI_DEV;
	}
	if (dev < 0 \|\| dev >= num_midis \|\| midi_devs[dev] == NULL)
	return -ENXIO;
	/*
	* Interrupts disabled. Be careful
	*/

	module_put(midi_devs[dev]->owner);

	if ((err = midi_devs[dev]->open(dev, mode,
	midi_input_intr, midi_output_intr)) < 0)
	return err;

	parms[dev].prech_timeout = MAX_SCHEDULE_TIMEOUT;
	midi_in_buf[dev] = (struct midi_buf *) vmalloc(sizeof(struct midi_buf));

	if (midi_in_buf[dev] == NULL)
	{
	printk(KERN_WARNING "midi: Can't allocate buffer\n");
	midi_devs[dev]->close(dev);
	return -EIO;
	}
	midi_in_buf[dev]->len = midi_in_buf[dev]->head = midi_in_buf[dev]->tail = 0;

	midi_out_buf[dev] = (struct midi_buf *) vmalloc(sizeof(struct midi_buf));

	if (midi_out_buf[dev] == NULL)
	{
	printk(KERN_WARNING "midi: Can't allocate buffer\n");
	midi_devs[dev]->close(dev);
	vfree(midi_in_buf[dev]);
	midi_in_buf[dev] = NULL;
	return -EIO;
	}
	midi_out_buf[dev]->len = midi_out_buf[dev]->head = midi_out_buf[dev]->tail = 0;
	open_devs++;

	init_waitqueue_head(&midi_sleeper[dev]);
	init_waitqueue_head(&input_sleeper[dev]);

	if (open_devs < 2) /* This was first open */
	{
	poll_timer.expires = 1 + jiffies;
	add_timer(&poll_timer); /* Start polling */
	}
	return err;
	}

	void MIDIbuf_release(int dev, struct file *file)
	{
	int mode;

	dev = dev >> 4;
	mode = translate_mode(file);

	if (dev < 0 \|\| dev >= num_midis \|\| midi_devs[dev] == NULL)
	return;

	/*
	* Wait until the queue is empty
	*/

	if (mode != OPEN_READ)
	{
	midi_devs[dev]->outputc(dev, 0xfe); /*
	* Active sensing to shut the
	* devices
	*/

	while (!signal_pending(current) && DATA_AVAIL(midi_out_buf[dev]))
	interruptible_sleep_on(&midi_sleeper[dev]);
	/*
	* Sync
	*/

	drain_midi_queue(dev); /*
	* Ensure the output queues are empty
	*/
	}

	midi_devs[dev]->close(dev);

	open_devs--;
	if (open_devs == 0)
	del_timer_sync(&poll_timer);
	vfree(midi_in_buf[dev]);
	vfree(midi_out_buf[dev]);
	midi_in_buf[dev] = NULL;
	midi_out_buf[dev] = NULL;

	module_put(midi_devs[dev]->owner);
	}

	int MIDIbuf_write(int dev, struct file file, const char __user buf, int count)
	{
	int c, n, i;
	unsigned char tmp_data;

	dev = dev >> 4;

	if (!count)
	return 0;

	c = 0;

	while (c < count)
	{
	n = SPACE_AVAIL(midi_out_buf[dev]);

	if (n == 0) { /*
	* No space just now.
	*/

	if (file->f_flags & O_NONBLOCK) {
	c = -EAGAIN;
	goto out;
	}

	interruptible_sleep_on(&midi_sleeper[dev]);
	if (signal_pending(current))
	{
	c = -EINTR;
	goto out;
	}
	n = SPACE_AVAIL(midi_out_buf[dev]);
	}
	if (n > (count - c))
	n = count - c;

	for (i = 0; i < n; i++)
	{
	/* BROKE BROKE BROKE - CANT DO THIS WITH CLI !! */
	/* yes, think the same, so I removed the cli() brackets
	QUEUE_BYTE is protected against interrupts */
	if (copy_from_user((char *) &tmp_data, &(buf)[c], 1)) {
	c = -EFAULT;
	goto out;
	}
	QUEUE_BYTE(midi_out_buf[dev], tmp_data);
	c++;
	}
	}
	out:
	return c;
	}


	int MIDIbuf_read(int dev, struct file file, char __user buf, int count)
	{
	int n, c = 0;
	unsigned char tmp_data;

	dev = dev >> 4;

	if (!DATA_AVAIL(midi_in_buf[dev])) { /*
	* No data yet, wait
	*/
	if (file->f_flags & O_NONBLOCK) {
	c = -EAGAIN;
	goto out;
	}
	interruptible_sleep_on_timeout(&input_sleeper[dev],
	parms[dev].prech_timeout);

	if (signal_pending(current))
	c = -EINTR; /* The user is getting restless */
	}
	if (c == 0 && DATA_AVAIL(midi_in_buf[dev])) /*
	* Got some bytes
	*/
	{
	n = DATA_AVAIL(midi_in_buf[dev]);
	if (n > count)
	n = count;
	c = 0;

	while (c < n)
	{
	char *fixit;
	REMOVE_BYTE(midi_in_buf[dev], tmp_data);
	fixit = (char *) &tmp_data;
	/* BROKE BROKE BROKE */
	/* yes removed the cli() brackets again
	should q->len,tail&head be atomic_t? */
	if (copy_to_user(&(buf)[c], fixit, 1)) {
	c = -EFAULT;
	goto out;
	}
	c++;
	}
	}
	out:
	return c;
	}

	int MIDIbuf_ioctl(int dev, struct file *file,
	unsigned int cmd, void __user *arg)
	{
	int val;

	dev = dev >> 4;

	if (((cmd >> 8) & 0xff) == 'C')
	{
	if (midi_devs[dev]->coproc) /* Coprocessor ioctl */
	return midi_devs[dev]->coproc->ioctl(midi_devs[dev]->coproc->devc, cmd, arg, 0);
	/* printk("/dev/midi%d: No coprocessor for this device\n", dev);*/
	return -ENXIO;
	}
	else
	{
	switch (cmd)
	{
	case SNDCTL_MIDI_PRETIME:
	if (get_user(val, (int __user *)arg))
	return -EFAULT;
	if (val < 0)
	val = 0;
	val = (HZ * val) / 10;
	parms[dev].prech_timeout = val;
	return put_user(val, (int __user *)arg);

	default:
	if (!midi_devs[dev]->ioctl)
	return -EINVAL;
	return midi_devs[dev]->ioctl(dev, cmd, arg);
	}
	}
	}

	/* No kernel lock - fine */
	unsigned int MIDIbuf_poll(int dev, struct file file, poll_table wait)
	{
	unsigned int mask = 0;

	dev = dev >> 4;

	/* input */
	poll_wait(file, &input_sleeper[dev], wait);
	if (DATA_AVAIL(midi_in_buf[dev]))
	mask \|= POLLIN \| POLLRDNORM;

	/* output */
	poll_wait(file, &midi_sleeper[dev], wait);
	if (!SPACE_AVAIL(midi_out_buf[dev]))
	mask \|= POLLOUT \| POLLWRNORM;

	return mask;
	}


	void MIDIbuf_init(void)
	{
	/* drag in midi_syms.o */
	{
	extern char midi_syms_symbol;
	midi_syms_symbol = 0;
	}
	}

	int MIDIbuf_avail(int dev)
	{
	if (midi_in_buf[dev])
	return DATA_AVAIL (midi_in_buf[dev]);
	return 0;
	}