beginnings of virtual playback channel support

instead of using two malloced arrays for storing channel lists, use an
slist.  convert the sndstat device to use sbufs and optionally provide more
detail about channel state.

vchans are software mixed playback channels.  they are not enabled by this
commit.  they use the feeder infrastructure to emulate normal playback
channels in a manner transparent to applications, whilst providing as many
channels are desired, especially suitable for devices with only one hardware
playback channel.  in the future they will provide additional features.

those wishing to test this functionality will need to add vchan.c to
sys/conf/files and use 'sysctl -w hw.snd.pcm0.vchans' to enable it.

blocksize and auto-rate selection are not yet supported.

10 files changed, 927 insertions, 212 deletions

diff --git a/sys/dev/sound/pcm/channel.c b/sys/dev/sound/pcm/channel.c
index 8eec528..727c509 100644
--- a/sys/dev/sound/pcm/channel.c
+++ b/sys/dev/sound/pcm/channel.c
@@ -121,6 +121,7 @@ chn_dmaupdate(struct pcm_channel *c)
 	struct snd_dbuf *b = c->bufhard;
 	unsigned int delta, old, hwptr, amt;
 
+	KASSERT(sndbuf_getsize(b) > 0, ("bufsize == 0"));
 	CHN_LOCKASSERT(c);
 	old = sndbuf_gethwptr(b);
 	hwptr = chn_getptr(c);
@@ -130,7 +131,7 @@ chn_dmaupdate(struct pcm_channel *c)
 	DEB(
 	if (delta >= ((sndbuf_getsize(b) * 15) / 16)) {
 		if (!(c->flags & (CHN_F_CLOSING | CHN_F_ABORTING)))
-			device_printf(c->parent->dev, "hwptr went backwards %d -> %d\n", old, hwptr);
+			device_printf(c->parentsnddev->dev, "hwptr went backwards %d -> %d\n", old, hwptr);
 	}
 	);
 
@@ -231,13 +232,13 @@ chn_write(struct pcm_channel *c, struct uio *buf)
 	 * the write operation avoids blocking.
 	 */
 	if ((c->flags & CHN_F_NBIO) && buf->uio_resid > sndbuf_getblksz(bs)) {
-		DEB(device_printf(c->parent->dev, "broken app, nbio and tried to write %d bytes with fragsz %d\n",
+		DEB(device_printf(c->parentsnddev->dev, "broken app, nbio and tried to write %d bytes with fragsz %d\n",
 			buf->uio_resid, sndbuf_getblksz(bs)));
 		newsize = 16;
 		while (newsize < min(buf->uio_resid, CHN_2NDBUFMAXSIZE / 2))
 			newsize <<= 1;
 		chn_setblocksize(c, sndbuf_getblkcnt(bs), newsize);
-		DEB(device_printf(c->parent->dev, "frags reset to %d x %d\n", sndbuf_getblkcnt(bs), sndbuf_getblksz(bs)));
+		DEB(device_printf(c->parentsnddev->dev, "frags reset to %d x %d\n", sndbuf_getblkcnt(bs), sndbuf_getblksz(bs)));
 	}
 
 	ret = 0;
@@ -271,7 +272,7 @@ chn_write(struct pcm_channel *c, struct uio *buf)
 
 	if (count <= 0) {
 		c->flags |= CHN_F_DEAD;
-		device_printf(c->parent->dev, "play interrupt timeout, channel dead\n");
+		device_printf(c->parentsnddev->dev, "play interrupt timeout, channel dead\n");
 	}
 
 	return ret;
@@ -391,7 +392,7 @@ chn_read(struct pcm_channel *c, struct uio *buf)
 
 	if (count <= 0) {
 		c->flags |= CHN_F_DEAD;
-		device_printf(c->parent->dev, "record interrupt timeout, channel dead\n");
+		device_printf(c->parentsnddev->dev, "record interrupt timeout, channel dead\n");
 	}
 
 	return ret;
@@ -423,8 +424,19 @@ chn_start(struct pcm_channel *c, int force)
 	i = (c->direction == PCMDIR_PLAY)? sndbuf_getready(bs) : sndbuf_getfree(bs);
 	if (force || (i >= sndbuf_getblksz(b))) {
 		c->flags |= CHN_F_TRIGGERED;
-		if (c->direction == PCMDIR_PLAY)
-			chn_wrfeed(c);
+		/*
+		 * if we're starting because a vchan started, don't feed any data
+		 * or it becomes impossible to start vchans synchronised with the
+		 * first one.  the hardbuf should be empty so we top it up with
+		 * silence to give it something to chew.  the real data will be
+		 * fed at the first irq.
+		 */
+		if (c->direction == PCMDIR_PLAY) {
+			if (SLIST_EMPTY(&c->children))
+				chn_wrfeed(c);
+			else
+				sndbuf_fillsilence(b);
+		}
 		sndbuf_setrun(b, 1);
 	    	chn_trigger(c, PCMTRIG_START);
 		return 0;
@@ -458,7 +470,6 @@ chn_sync(struct pcm_channel *c, int threshold)
 
 	CHN_LOCKASSERT(c);
     	for (;;) {
-		chn_wrupdate(c);
 		rdy = (c->direction == PCMDIR_PLAY)? sndbuf_getfree(bs) : sndbuf_getready(bs);
 		if (rdy <= threshold) {
 	    		ret = chn_sleep(c, "pcmsyn", 1);
@@ -495,7 +506,7 @@ chn_poll(struct pcm_channel *c, int ev, struct proc *p)
  * chn_abort terminates a running dma transfer.  it may sleep up to 200ms.
  * it returns the number of bytes that have not been transferred.
  *
- * called from: dsp_close, dsp_ioctl, with both bufhards locked
+ * called from: dsp_close, dsp_ioctl, with channel locked
  */
 int
 chn_abort(struct pcm_channel *c)
@@ -509,7 +520,10 @@ chn_abort(struct pcm_channel *c)
 		return 0;
 	c->flags |= CHN_F_ABORTING;
 
-	/* wait up to 200ms for the secondary bufhard to empty */
+	/*
+	 * wait up to 200ms for the secondary buffer to empty-
+	 * a vchan will never have data in the secondary buffer so we won't sleep
+	 */
 	cnt = 10;
 	while ((sndbuf_getready(bs) > 0) && (cnt-- > 0)) {
 		chn_sleep(c, "pcmabr", hz / 50);
@@ -649,7 +663,7 @@ chn_init(struct pcm_channel *c, void *devinfo, int dir)
 		sndbuf_destroy(b);
 		return ENODEV;
 	}
-	if (sndbuf_getsize(b) == 0) {
+	if ((sndbuf_getsize(b) == 0) && ((c->flags & CHN_F_VIRTUAL) == 0)) {
 		sndbuf_destroy(bs);
 		sndbuf_destroy(b);
 		return ENOMEM;
@@ -714,6 +728,7 @@ chn_tryspeed(struct pcm_channel *c, int speed)
 	int r, delta;
 
 	CHN_LOCKASSERT(c);
+	DEB(printf("setspeed, channel %s\n", c->name));
 	DEB(printf("want speed %d, ", speed));
 	if (speed <= 0)
 		return EINVAL;
@@ -724,7 +739,7 @@ chn_tryspeed(struct pcm_channel *c, int speed)
 		RANGE(speed, chn_getcaps(c)->minspeed, chn_getcaps(c)->maxspeed);
 		DEB(printf("try speed %d, ", speed));
 		sndbuf_setspd(b, CHANNEL_SETSPEED(c->methods, c->devinfo, speed));
-		DEB(printf("got speed %d, ", sndbuf_getspd(b)));
+		DEB(printf("got speed %d\n", sndbuf_getspd(b)));
 
 		delta = sndbuf_getspd(b) - sndbuf_getspd(bs);
 		if (delta < 0)
@@ -762,6 +777,7 @@ chn_tryspeed(struct pcm_channel *c, int speed)
 		r = FEEDER_SET(f, FEEDRATE_DST, sndbuf_getspd(b));
 		DEB(printf("feeder_set(FEEDRATE_DST, %d) = %d\n", sndbuf_getspd(b), r));
 out:
+		DEB(printf("setspeed done, r = %d\n", r));
 		return r;
 	} else
 		return EINVAL;
@@ -957,17 +973,32 @@ chn_buildfeeder(struct pcm_channel *c)
 
 	c->align = sndbuf_getalign(c->bufsoft);
 
-	fc = feeder_getclass(NULL);
-	if (fc == NULL) {
-		DEB(printf("can't find root feeder\n"));
-		return EINVAL;
-	}
-	if (chn_addfeeder(c, fc, NULL)) {
-		DEB(printf("can't add root feeder\n"));
-		return EINVAL;
+	if (SLIST_EMPTY(&c->children)) {
+		fc = feeder_getclass(NULL);
+		if (fc == NULL) {
+			DEB(printf("can't find root feeder\n"));
+			return EINVAL;
+		}
+		if (chn_addfeeder(c, fc, NULL)) {
+			DEB(printf("can't add root feeder\n"));
+			return EINVAL;
+		}
+		c->feeder->desc->out = c->format;
+	} else {
+		desc.type = FEEDER_MIXER;
+		desc.in = 0;
+		desc.out = c->format;
+		desc.flags = 0;
+		fc = feeder_getclass(&desc);
+		if (fc == NULL) {
+			DEB(printf("can't find vchan feeder\n"));
+			return EINVAL;
+		}
+		if (chn_addfeeder(c, fc, &desc)) {
+			DEB(printf("can't add vchan feeder\n"));
+			return EINVAL;
+		}
 	}
-	c->feeder->desc->out = c->format;
-
 	flags = c->feederflags;
 
 	if ((c->flags & CHN_F_MAPPED) && (flags != 0)) {
@@ -1020,3 +1051,63 @@ chn_buildfeeder(struct pcm_channel *c)
 	return 0;
 }
 
+int
+chn_notify(struct pcm_channel *c, u_int32_t flags)
+{
+	struct pcmchan_children *pce;
+	struct pcm_channel *child;
+
+	if (SLIST_EMPTY(&c->children))
+		return ENODEV;
+
+	if (flags & CHN_N_RATE) {
+		/*
+		 * we could do something here, like scan children and decide on
+		 * the most appropriate rate to mix at, but we don't for now
+		 */
+	}
+	if (flags & CHN_N_FORMAT) {
+		/*
+		 * we could do something here, like scan children and decide on
+		 * the most appropriate mixer feeder to use, but we don't for now
+		 */
+	}
+	if (flags & CHN_N_VOLUME) {
+		/*
+		 * we could do something here but we don't for now
+		 */
+	}
+	if (flags & CHN_N_BLOCKSIZE) {
+		int blksz;
+		/*
+		 * scan the children, find the lowest blocksize and use that
+		 * for the hard blocksize
+		 */
+		blksz = sndbuf_getmaxsize(c->bufhard) / 2;
+		SLIST_FOREACH(pce, &c->children, link) {
+			child = pce->channel;
+			if (sndbuf_getblksz(child->bufhard) < blksz)
+				blksz = sndbuf_getblksz(child->bufhard);
+		}
+		chn_setblocksize(c, 2, blksz);
+	}
+	if (flags & CHN_N_TRIGGER) {
+		int run;
+		/*
+		 * scan the children, and figure out if any are running
+		 * if so, we need to be running, otherwise we need to be stopped
+		 * if we aren't in our target sstate, move to it
+		 */
+		run = 0;
+		SLIST_FOREACH(pce, &c->children, link) {
+			child = pce->channel;
+			if (child->flags & CHN_F_TRIGGERED)
+				run = 1;
+		}
+		if (run && !(c->flags & CHN_F_TRIGGERED))
+			chn_start(c, 1);
+		if (!run && (c->flags & CHN_F_TRIGGERED))
+			chn_abort(c);
+	}
+	return 0;
+}
diff --git a/sys/dev/sound/pcm/channel.h b/sys/dev/sound/pcm/channel.h
index 2b4bfba..bc0dff2 100644
--- a/sys/dev/sound/pcm/channel.h
+++ b/sys/dev/sound/pcm/channel.h
@@ -26,6 +26,11 @@
  * $FreeBSD$
  */
 
+struct pcmchan_children {
+	SLIST_ENTRY(pcmchan_children) link;
+	struct pcm_channel *channel;
+};
+
 struct pcmchan_caps {
 	u_int32_t minspeed, maxspeed;
 	u_int32_t *fmtlist;
@@ -36,6 +41,8 @@ struct pcmchan_caps {
 struct pcm_channel {
 	kobj_t methods;
 
+	pid_t pid;
+	int refcount;
 	struct pcm_feeder *feeder;
 	u_int32_t align;
 
@@ -48,10 +55,12 @@ struct pcm_channel {
 
 	int direction;
 	struct snd_dbuf *bufhard, *bufsoft;
-	struct snddev_info *parent;
+	struct snddev_info *parentsnddev;
+	struct pcm_channel *parentchannel;
 	void *devinfo;
 	char name[CHN_NAMELEN];
 	void *lock;
+	SLIST_HEAD(, pcmchan_children) children;
 };
 
 #include "channel_if.h"
@@ -86,12 +95,15 @@ int chn_abort(struct pcm_channel *c);
 void chn_wrupdate(struct pcm_channel *c);
 void chn_rdupdate(struct pcm_channel *c);
 
+int chn_notify(struct pcm_channel *c, u_int32_t flags);
+
 #define CHN_LOCK(c) mtx_lock((struct mtx *)((c)->lock))
 #define CHN_UNLOCK(c) mtx_unlock((struct mtx *)((c)->lock))
 #define CHN_LOCKASSERT(c)
 
 int fmtvalid(u_int32_t fmt, u_int32_t *fmtlist);
 
+#define PCMDIR_VIRTUAL 2
 #define PCMDIR_PLAY 1
 #define PCMDIR_REC -1
 
@@ -114,7 +126,15 @@ int fmtvalid(u_int32_t fmt, u_int32_t *fmtlist);
 #define CHN_F_DEAD		0x00020000
 #define CHN_F_BADSETTING	0x00040000
 
-#define CHN_F_RESET		(CHN_F_BUSY | CHN_F_DEAD)
+#define	CHN_F_VIRTUAL		0x10000000  /* not backed by hardware */
+
+#define CHN_F_RESET		(CHN_F_BUSY | CHN_F_DEAD | CHN_F_VIRTUAL)
+
+#define CHN_N_RATE		0x00000001
+#define CHN_N_FORMAT		0x00000002
+#define CHN_N_VOLUME		0x00000004
+#define CHN_N_BLOCKSIZE		0x00000008
+#define CHN_N_TRIGGER		0x00000010
 
 /*
  * This should be large enough to hold all pcm data between
diff --git a/sys/dev/sound/pcm/channel_if.m b/sys/dev/sound/pcm/channel_if.m
index c5675da..9d8e289 100644
--- a/sys/dev/sound/pcm/channel_if.m
+++ b/sys/dev/sound/pcm/channel_if.m
@@ -57,6 +57,18 @@ CODE {
 		return 1;
 	}
 
+	static u_int32_t
+	channel_nogetptr(kobj_t obj, void *data)
+	{
+		return 0;
+	}
+
+	static int
+	channel_nonotify(kobj_t obj, void *data, u_int32_t changed)
+	{
+		return 0;
+	}
+
 };
 
 METHOD void* init {
@@ -115,10 +127,15 @@ METHOD int trigger {
 METHOD u_int32_t getptr {
 	kobj_t obj;
 	void *data;
-};
+} DEFAULT channel_nogetptr;
 
 METHOD struct pcmchan_caps* getcaps {
 	kobj_t obj;
 	void *data;
 };
 
+METHOD int notify {
+	kobj_t obj;
+	void *data;
+	u_int32_t changed;
+} DEFAULT channel_nonotify;
diff --git a/sys/dev/sound/pcm/dsp.c b/sys/dev/sound/pcm/dsp.c
index 0954442..c31d955 100644
--- a/sys/dev/sound/pcm/dsp.c
+++ b/sys/dev/sound/pcm/dsp.c
@@ -33,22 +33,6 @@
 
 #define OLDPCM_IOCTL
 
-static int getchns(struct snddev_info *d, int chan, struct pcm_channel **rdch, struct pcm_channel **wrch);
-
-static struct pcm_channel *
-allocchn(struct snddev_info *d, int direction)
-{
-	struct pcm_channel *chns = (direction == PCMDIR_PLAY)? d->play : d->rec;
-	int i, cnt = (direction == PCMDIR_PLAY)? d->playcount : d->reccount;
-	for (i = 0; i < cnt; i++) {
-		if (!(chns[i].flags & (CHN_F_BUSY | CHN_F_DEAD))) {
-			chns[i].flags |= CHN_F_BUSY;
-			return &chns[i];
-		}
-	}
-	return NULL;
-}
-
 static int
 getchns(struct snddev_info *d, int chan, struct pcm_channel **rdch, struct pcm_channel **wrch)
 {
@@ -75,35 +59,54 @@ setchns(struct snddev_info *d, int chan)
 }
 
 int
-dsp_open(struct snddev_info *d, int chan, int oflags, int devtype)
+dsp_open(struct snddev_info *d, int chan, int oflags, int devtype, pid_t pid)
 {
 	struct pcm_channel *rdch, *wrch;
 	u_int32_t fmt;
 
-	if (chan >= d->chancount) return ENODEV;
-	if ((d->flags & SD_F_SIMPLEX) && (d->ref[chan] > 0)) return EBUSY;
+	if (chan >= d->chancount)
+		return ENODEV;
+	if ((d->flags & SD_F_SIMPLEX) && (d->arec[chan] || d->aplay[chan]))
+		return EBUSY;
 
 	rdch = d->arec[chan];
 	wrch = d->aplay[chan];
+
 	if (oflags & FREAD) {
 		if (rdch == NULL) {
-			rdch = allocchn(d, PCMDIR_REC);
-			if (!rdch) return EBUSY;
-		} else return EBUSY;
+			rdch = pcm_chnalloc(d, PCMDIR_REC);
+			if (!rdch)
+				return EBUSY;
+			rdch->pid = pid;
+		} else
+			return EBUSY;
 	}
+
 	if (oflags & FWRITE) {
 		if (wrch == NULL) {
-			wrch = allocchn(d, PCMDIR_PLAY);
+			wrch = pcm_chnalloc(d, PCMDIR_PLAY);
 			if (!wrch) {
 				if (rdch && (oflags & FREAD))
-					rdch->flags &= ~CHN_F_BUSY;
+					pcm_chnfree(rdch);
 				return EBUSY;
 			}
-		} else return EBUSY;
+			wrch->pid = pid;
+		} else
+			return EBUSY;
+	}
+
+	if (rdch) {
+		CHN_LOCK(rdch);
+		pcm_chnref(rdch, 1);
+	}
+	if (wrch) {
+		CHN_LOCK(wrch);
+		pcm_chnref(wrch, 1);
 	}
+
 	d->aplay[chan] = wrch;
 	d->arec[chan] = rdch;
-	d->ref[chan]++;
+
 	switch (devtype) {
 	case SND_DEV_DSP16:
 		fmt = AFMT_S16_LE;
@@ -124,10 +127,6 @@ dsp_open(struct snddev_info *d, int chan, int oflags, int devtype)
 	default:
 		return ENXIO;
 	}
-	if (rdch)
-		CHN_LOCK(rdch);
-	if (wrch)
-		CHN_LOCK(wrch);
 
 	if (rdch && (oflags & FREAD)) {
 	        chn_reset(rdch, fmt);
@@ -149,28 +148,38 @@ dsp_close(struct snddev_info *d, int chan, int devtype)
 {
 	struct pcm_channel *rdch, *wrch;
 
-	d->ref[chan]--;
-	if (d->ref[chan]) return 0;
-	d->flags &= ~SD_F_TRANSIENT;
 	rdch = d->arec[chan];
 	wrch = d->aplay[chan];
 
+	if (rdch && pcm_chnref(rdch, -1))
+		return 0;
+	if (wrch && pcm_chnref(wrch, -1))
+		return 0;
+
+	d->aplay[chan] = NULL;
+	d->arec[chan] = NULL;
+
+	d->flags &= ~SD_F_TRANSIENT;
+
 	if (rdch) {
 		CHN_LOCK(rdch);
 		chn_abort(rdch);
-		rdch->flags &= ~(CHN_F_BUSY | CHN_F_RUNNING | CHN_F_MAPPED | CHN_F_DEAD);
+		rdch->flags &= ~(CHN_F_RUNNING | CHN_F_MAPPED | CHN_F_DEAD);
 		chn_reset(rdch, 0);
+		rdch->pid = -1;
+		pcm_chnfree(rdch);
 		CHN_UNLOCK(rdch);
 	}
 	if (wrch) {
 		CHN_LOCK(wrch);
 		chn_flush(wrch);
-		wrch->flags &= ~(CHN_F_BUSY | CHN_F_RUNNING | CHN_F_MAPPED | CHN_F_DEAD);
+		wrch->flags &= ~(CHN_F_RUNNING | CHN_F_MAPPED | CHN_F_DEAD);
 		chn_reset(wrch, 0);
+		wrch->pid = -1;
+		pcm_chnfree(wrch);
 		CHN_UNLOCK(wrch);
 	}
-	d->aplay[chan] = NULL;
-	d->arec[chan] = NULL;
+
 	return 0;
 }
 
diff --git a/sys/dev/sound/pcm/dsp.h b/sys/dev/sound/pcm/dsp.h
index 89d0624..8fa1a9e 100644
--- a/sys/dev/sound/pcm/dsp.h
+++ b/sys/dev/sound/pcm/dsp.h
@@ -26,7 +26,7 @@
  * $FreeBSD$
  */
 
-int dsp_open(struct snddev_info *d, int chan, int oflags, int devtype);
+int dsp_open(struct snddev_info *d, int chan, int oflags, int devtype, pid_t pid);
 int dsp_close(struct snddev_info *d, int chan, int devtype);
 int dsp_read(struct snddev_info *d, int chan, struct uio *buf, int flag);
 int dsp_write(struct snddev_info *d, int chan, struct uio *buf, int flag);
diff --git a/sys/dev/sound/pcm/fake.c b/sys/dev/sound/pcm/fake.c
index 9001653..aeb47ef 100644
--- a/sys/dev/sound/pcm/fake.c
+++ b/sys/dev/sound/pcm/fake.c
@@ -119,7 +119,7 @@ fkchan_setup(device_t dev)
 
 	c = malloc(sizeof(*c), M_DEVBUF, M_WAITOK);
 	c->methods = kobj_create(&fkchan_class, M_DEVBUF, M_WAITOK);
-	c->parent = d;
+	c->parentsnddev = d;
 	snprintf(c->name, CHN_NAMELEN, "%s:fake", device_get_nameunit(dev));
 
 	return c;
diff --git a/sys/dev/sound/pcm/sound.c b/sys/dev/sound/pcm/sound.c
index a3039e3..7fb6951 100644
--- a/sys/dev/sound/pcm/sound.c
+++ b/sys/dev/sound/pcm/sound.c
@@ -28,12 +28,16 @@
  */
 
 #include <dev/sound/pcm/sound.h>
+#include <dev/sound/pcm/vchan.h>
 #include <sys/sysctl.h>
+#include <sys/sbuf.h>
 
-static dev_t 	status_dev = 0;
-static int 	status_isopen = 0;
-static int 	status_init(char *buf, int size);
-static int 	status_read(struct uio *buf);
+#include "feeder_if.h"
+
+#undef	SNDSTAT_VERBOSE
+
+static dev_t status_dev = 0;
+static int do_status(int action, struct uio *buf);
 
 static d_open_t sndopen;
 static d_close_t sndclose;
@@ -88,7 +92,7 @@ nomenclature:
 static devclass_t pcm_devclass;
 
 #ifdef USING_DEVFS
-int snd_unit;
+static int snd_unit;
 TUNABLE_INT_DECL("hw.snd.unit", 0, snd_unit);
 #endif
 
@@ -164,6 +168,36 @@ snd_setup_intr(device_t dev, struct resource *res, int flags, driver_intr_t hand
 	return bus_setup_intr(dev, res, flags, hand, param, cookiep);
 }
 
+struct pcm_channel *
+pcm_chnalloc(struct snddev_info *d, int direction)
+{
+	struct pcm_channel *c;
+    	struct snddev_channel *sce;
+
+	SLIST_FOREACH(sce, &d->channels, link) {
+		c = sce->channel;
+		if ((c->direction == direction) && !(c->flags & CHN_F_BUSY)) {
+			c->flags |= CHN_F_BUSY;
+			return c;
+		}
+	}
+	return NULL;
+}
+
+int
+pcm_chnfree(struct pcm_channel *c)
+{
+	c->flags &= ~CHN_F_BUSY;
+	return 0;
+}
+
+int
+pcm_chnref(struct pcm_channel *c, int ref)
+{
+	c->refcount += ref;
+	return c->refcount;
+}
+
 #ifdef USING_DEVFS
 static void
 pcm_makelinks(void *dummy)
@@ -171,6 +205,7 @@ pcm_makelinks(void *dummy)
 	int unit;
 	dev_t pdev;
 	static dev_t dsp = 0, dspW = 0, audio = 0, mixer = 0;
+    	struct snddev_info *d;
 
 	if (pcm_devclass == NULL || devfs_present == 0)
 		return;
@@ -194,7 +229,8 @@ pcm_makelinks(void *dummy)
 	unit = snd_unit;
 	if (unit < 0 || unit > devclass_get_maxunit(pcm_devclass))
 		return;
-	if (devclass_get_softc(pcm_devclass, unit) == NULL)
+	d = devclass_get_softc(pcm_devclass, unit);
+	if (d == NULL || d->chancount == 0)
 		return;
 
 	pdev = makedev(CDEV_MAJOR, PCMMKMINOR(unit, SND_DEV_DSP, 0));
@@ -224,32 +260,86 @@ SYSCTL_PROC(_hw_snd, OID_AUTO, unit, CTLTYPE_INT | CTLFLAG_RW,
             0, sizeof(int), sysctl_hw_sndunit, "I", "");
 #endif
 
-int
-pcm_addchan(device_t dev, int dir, kobj_class_t cls, void *devinfo)
+struct pcm_channel *
+pcm_chn_create(struct snddev_info *d, struct pcm_channel *parent, kobj_class_t cls, int dir, void *devinfo)
 {
-    	int unit = device_get_unit(dev), idx;
-    	struct snddev_info *d = device_get_softc(dev);
-	struct pcm_channel *chns, *ch;
+	struct pcm_channel *ch;
 	char *dirs;
-	int err;
-
-	dirs = ((dir == PCMDIR_PLAY)? "play" : "record");
-	chns = ((dir == PCMDIR_PLAY)? d->play : d->rec);
-	idx = ((dir == PCMDIR_PLAY)? d->playcount++ : d->reccount++);
+    	int err;
 
-	if (chns == NULL) {
-		device_printf(dev, "bad channel add (%s:%d)\n", dirs, idx);
-		return 1;
+	switch(dir) {
+	case PCMDIR_PLAY:
+		dirs = "play";
+		break;
+	case PCMDIR_REC:
+		dirs = "record";
+		break;
+	case PCMDIR_VIRTUAL:
+		dirs = "virtual";
+		dir = PCMDIR_PLAY;
+		break;
+	default:
+		return NULL;
 	}
-	ch = &chns[idx];
+
+	ch = malloc(sizeof(*ch), M_DEVBUF, M_WAITOK | M_ZERO);
+	if (!ch)
+		return NULL;
+
 	ch->methods = kobj_create(cls, M_DEVBUF, M_WAITOK);
-	ch->parent = d;
-	snprintf(ch->name, 32, "%s:%s:%d", device_get_nameunit(dev), dirs, idx);
+	if (!ch->methods) {
+		free(ch, M_DEVBUF);
+		return NULL;
+	}
+
+	ch->pid = -1;
+	ch->parentsnddev = d;
+	ch->parentchannel = parent;
+	snprintf(ch->name, 32, "%s:%d:%s", device_get_nameunit(d->dev), d->chancount, dirs);
+
 	err = chn_init(ch, devinfo, dir);
 	if (err) {
-		device_printf(dev, "chn_init() for (%s:%d) failed: err = %d\n", dirs, idx, err);
-		return 1;
+		device_printf(d->dev, "chn_init() for channel %d (%s) failed: err = %d\n", d->chancount, dirs, err);
+		kobj_delete(ch->methods, M_DEVBUF);
+		free(ch, M_DEVBUF);
+		return NULL;
+	}
+
+	return ch;
+}
+
+int
+pcm_chn_destroy(struct pcm_channel *ch)
+{
+	int err;
+
+	err = chn_kill(ch);
+	if (err) {
+		device_printf(ch->parentsnddev->dev, "chn_kill() for %s failed, err = %d\n", ch->name, err);
+		return err;
 	}
+
+	kobj_delete(ch->methods, M_DEVBUF);
+	free(ch, M_DEVBUF);
+
+	return 0;
+}
+
+int
+pcm_chn_add(struct snddev_info *d, struct pcm_channel *ch)
+{
+    	struct snddev_channel *sce;
+    	int unit = device_get_unit(d->dev);
+
+	sce = malloc(sizeof(*sce), M_DEVBUF, M_WAITOK | M_ZERO);
+	if (!sce) {
+		free(ch, M_DEVBUF);
+		return ENOMEM;
+	}
+
+	sce->channel = ch;
+	SLIST_INSERT_HEAD(&d->channels, sce, link);
+
 	make_dev(&snd_cdevsw, PCMMKMINOR(unit, SND_DEV_DSP, d->chancount),
 		 UID_ROOT, GID_WHEEL, 0666, "dsp%d.%d", unit, d->chancount);
 	make_dev(&snd_cdevsw, PCMMKMINOR(unit, SND_DEV_DSP16, d->chancount),
@@ -257,49 +347,79 @@ pcm_addchan(device_t dev, int dir, kobj_class_t cls, void *devinfo)
 	make_dev(&snd_cdevsw, PCMMKMINOR(unit, SND_DEV_AUDIO, d->chancount),
 		 UID_ROOT, GID_WHEEL, 0666, "audio%d.%d", unit, d->chancount);
 	/* XXX SND_DEV_NORESET? */
-	d->chancount++;
+
 #ifdef USING_DEVFS
-    	if (d->chancount == 1)
+    	if (d->chancount++ == 0)
 		pcm_makelinks(NULL);
 #endif
+
 	return 0;
 }
 
-static int
-pcm_killchan(device_t dev, int dir)
+int
+pcm_chn_remove(struct snddev_info *d, struct pcm_channel *ch)
 {
-    	int unit = device_get_unit(dev), idx;
-    	struct snddev_info *d = device_get_softc(dev);
-	struct pcm_channel *chns, *ch;
-	char *dirs;
+    	struct snddev_channel *sce;
+    	int unit = device_get_unit(d->dev);
 	dev_t pdev;
 
-	dirs = ((dir == PCMDIR_PLAY)? "play" : "record");
-	chns = ((dir == PCMDIR_PLAY)? d->play : d->rec);
-	idx = ((dir == PCMDIR_PLAY)? --d->playcount : --d->reccount);
-
-	if (chns == NULL || idx < 0) {
-		device_printf(dev, "bad channel kill (%s:%d)\n", dirs, idx);
-		return 1;
-	}
-	ch = &chns[idx];
-	if (chn_kill(ch)) {
-		device_printf(dev, "chn_kill() for (%s:%d) failed\n", dirs, idx);
-		return 1;
+	SLIST_FOREACH(sce, &d->channels, link) {
+		if (sce->channel == ch)
+			goto gotit;
 	}
-	kobj_delete(ch->methods, M_DEVBUF);
-	ch->methods = NULL;
+	return EINVAL;
+gotit:
 	d->chancount--;
+	SLIST_REMOVE(&d->channels, sce, snddev_channel, link);
+	free(sce, M_DEVBUF);
+
+#ifdef USING_DEVFS
+    	if (d->chancount == 0)
+		pcm_makelinks(NULL);
+#endif
 	pdev = makedev(CDEV_MAJOR, PCMMKMINOR(unit, SND_DEV_DSP, d->chancount));
 	destroy_dev(pdev);
 	pdev = makedev(CDEV_MAJOR, PCMMKMINOR(unit, SND_DEV_DSP16, d->chancount));
 	destroy_dev(pdev);
 	pdev = makedev(CDEV_MAJOR, PCMMKMINOR(unit, SND_DEV_AUDIO, d->chancount));
 	destroy_dev(pdev);
+
 	return 0;
 }
 
 int
+pcm_addchan(device_t dev, int dir, kobj_class_t cls, void *devinfo)
+{
+    	struct snddev_info *d = device_get_softc(dev);
+	struct pcm_channel *ch;
+    	int err;
+
+	ch = pcm_chn_create(d, NULL, cls, dir, devinfo);
+	if (!ch) {
+		device_printf(d->dev, "pcm_chn_create(%s, %d, %p) failed\n", cls->name, dir, devinfo);
+		return ENODEV;
+	}
+	err = pcm_chn_add(d, ch);
+	if (err) {
+		device_printf(d->dev, "pcm_chn_add(%s) failed, err=%d\n", ch->name, err);
+		pcm_chn_destroy(ch);
+	}
+
+	return err;
+}
+
+static int
+pcm_killchan(device_t dev)
+{
+    	struct snddev_info *d = device_get_softc(dev);
+    	struct snddev_channel *sce;
+
+	sce = SLIST_FIRST(&d->channels);
+
+	return pcm_chn_remove(d, sce->channel);
+}
+
+int
 pcm_setstatus(device_t dev, char *str)
 {
     	struct snddev_info *d = device_get_softc(dev);
@@ -340,44 +460,27 @@ pcm_register(device_t dev, void *devinfo, int numplay, int numrec)
 		status_dev = make_dev(&snd_cdevsw, PCMMKMINOR(0, SND_DEV_STATUS, 0),
 			 UID_ROOT, GID_WHEEL, 0444, "sndstat");
 	}
+
 	make_dev(&snd_cdevsw, PCMMKMINOR(unit, SND_DEV_CTL, 0),
 		 UID_ROOT, GID_WHEEL, 0666, "mixer%d", unit);
+
 	d->dev = dev;
 	d->devinfo = devinfo;
-	d->chancount = d->playcount = d->reccount = 0;
+	d->chancount = 0;
 	d->maxchans = numplay + numrec;
-    	sz = (numplay + numrec) * sizeof(struct pcm_channel *);
+    	sz = d->maxchans * sizeof(struct pcm_channel *);
 
 	if (sz > 0) {
-		d->aplay = (struct pcm_channel **)malloc(sz, M_DEVBUF, M_NOWAIT);
-    		if (!d->aplay) goto no;
-    		bzero(d->aplay, sz);
-
-    		d->arec = (struct pcm_channel **)malloc(sz, M_DEVBUF, M_NOWAIT);
-    		if (!d->arec) goto no;
-    		bzero(d->arec, sz);
-
-    		sz = (numplay + numrec) * sizeof(int);
-		d->ref = (int *)malloc(sz, M_DEVBUF, M_NOWAIT);
-    		if (!d->ref) goto no;
-    		bzero(d->ref, sz);
-	}
+		d->aplay = (struct pcm_channel **)malloc(sz, M_DEVBUF, M_WAITOK | M_ZERO);
+    		d->arec = (struct pcm_channel **)malloc(sz, M_DEVBUF, M_WAITOK | M_ZERO);
+    		if (!d->arec || !d->aplay) goto no;
 
-	if (numplay > 0) {
-    		d->play = (struct pcm_channel *)malloc(numplay * sizeof(struct pcm_channel),
-						M_DEVBUF, M_NOWAIT);
-    		if (!d->play) goto no;
-    		bzero(d->play, numplay * sizeof(struct pcm_channel));
-	} else
-		d->play = NULL;
-
-	if (numrec > 0) {
-	  	d->rec = (struct pcm_channel *)malloc(numrec * sizeof(struct pcm_channel),
-				       	M_DEVBUF, M_NOWAIT);
-    		if (!d->rec) goto no;
-    		bzero(d->rec, numrec * sizeof(struct pcm_channel));
-	} else
-		d->rec = NULL;
+		if (numplay == 0 || numrec == 0)
+			d->flags |= SD_F_SIMPLEX;
+
+		d->fakechan = fkchan_setup(dev);
+		chn_init(d->fakechan, NULL, 0);
+	}
 
 #ifdef SND_DYNSYSCTL
 	sysctl_ctx_init(&d->sysctl_tree);
@@ -389,36 +492,29 @@ pcm_register(device_t dev, void *devinfo, int numplay, int numrec)
 		goto no;
 	}
 #endif
-
-	if (numplay == 0 || numrec == 0)
-		d->flags |= SD_F_SIMPLEX;
-
-	d->fakechan = fkchan_setup(dev);
-	chn_init(d->fakechan, NULL, 0);
-
+#if 0
+	vchan_initsys(d);
+#endif
     	return 0;
 no:
 	if (d->aplay) free(d->aplay, M_DEVBUF);
-	if (d->play) free(d->play, M_DEVBUF);
 	if (d->arec) free(d->arec, M_DEVBUF);
-	if (d->rec) free(d->rec, M_DEVBUF);
-	if (d->ref) free(d->ref, M_DEVBUF);
 	return ENXIO;
 }
 
 int
 pcm_unregister(device_t dev)
 {
-    	int r, i, unit = device_get_unit(dev);
+    	int unit = device_get_unit(dev);
     	struct snddev_info *d = device_get_softc(dev);
+    	struct snddev_channel *sce;
 	dev_t pdev;
 
-	r = 0;
-	for (i = 0; i < d->chancount; i++)
-		if (d->ref[i]) r = EBUSY;
-	if (r) {
-		device_printf(dev, "unregister: channel busy");
-		return r;
+	SLIST_FOREACH(sce, &d->channels, link) {
+		if (sce->channel->refcount > 0) {
+			device_printf(dev, "unregister: channel busy");
+			return EBUSY;
+		}
 	}
 	if (mixer_isbusy(d->mixer)) {
 		device_printf(dev, "unregister: mixer busy");
@@ -434,23 +530,15 @@ pcm_unregister(device_t dev)
 	destroy_dev(pdev);
 	mixer_uninit(dev);
 
-	while (d->playcount > 0)
-		pcm_killchan(dev, PCMDIR_PLAY);
-	while (d->reccount > 0)
-		pcm_killchan(dev, PCMDIR_REC);
+	while (d->chancount > 0)
+		pcm_killchan(dev);
 
 	if (d->aplay) free(d->aplay, M_DEVBUF);
-	if (d->play) free(d->play, M_DEVBUF);
 	if (d->arec) free(d->arec, M_DEVBUF);
-	if (d->rec) free(d->rec, M_DEVBUF);
-	if (d->ref) free(d->ref, M_DEVBUF);
 
 	chn_kill(d->fakechan);
 	fkchan_kill(d->fakechan);
 
-#ifdef USING_DEVFS
-	pcm_makelinks(NULL);
-#endif
 	return 0;
 }
 
@@ -506,9 +594,7 @@ sndopen(dev_t i_dev, int flags, int mode, struct proc *p)
 
     	switch(dev) {
     	case SND_DEV_STATUS:
-		if (status_isopen) return EBUSY;
-		status_isopen = 1;
-		return 0;
+		return do_status(0, NULL);
 
     	case SND_DEV_CTL:
 		return d? mixer_busy(d->mixer, 1) : ENXIO;
@@ -517,7 +603,7 @@ sndopen(dev_t i_dev, int flags, int mode, struct proc *p)
     	case SND_DEV_DSP:
     	case SND_DEV_DSP16:
 	case SND_DEV_NORESET:
-		return d? dsp_open(d, chan, flags, dev) : ENXIO;
+		return d? dsp_open(d, chan, flags, dev, p->p_pid) : ENXIO;
 
     	default:
     		return ENXIO;
@@ -534,9 +620,7 @@ sndclose(dev_t i_dev, int flags, int mode, struct proc *p)
 
     	switch(dev) { /* only those for which close makes sense */
     	case SND_DEV_STATUS:
-		if (!status_isopen) return EBADF;
-		status_isopen = 0;
-		return 0;
+		return do_status(1, NULL);
 
     	case SND_DEV_CTL:
 		return d? mixer_busy(d->mixer, 0) : ENXIO;
@@ -560,7 +644,7 @@ sndread(dev_t i_dev, struct uio *buf, int flag)
 
     	switch(dev) {
     	case SND_DEV_STATUS:
-		return status_isopen? status_read(buf) : EBADF;
+		return do_status(2, buf);
 
     	case SND_DEV_AUDIO:
     	case SND_DEV_DSP:
@@ -675,52 +759,116 @@ sndmmap(dev_t i_dev, vm_offset_t offset, int nprot)
 }
 
 static int
-status_init(char *buf, int size)
+status_init(struct sbuf *s)
 {
-    	int             i;
-    	device_t	    dev;
-    	struct snddev_info     *d;
+    	int i, pc, rc, vc;
+    	device_t dev;
+    	struct snddev_info *d;
+    	struct snddev_channel *sce;
+	struct pcm_channel *c;
+	struct pcm_feeder *f;
 
-    	snprintf(buf, size, "FreeBSD Audio Driver (newpcm) %s %s\n"
-		 "Installed devices:\n", __DATE__, __TIME__);
+	sbuf_printf(s, "FreeBSD Audio Driver (newpcm) %s %s\nInstalled devices:\n",
+		 	__DATE__, __TIME__);
 
     	for (i = 0; i <= devclass_get_maxunit(pcm_devclass); i++) {
 		d = devclass_get_softc(pcm_devclass, i);
-		if (!d) continue;
+		if (!d)
+			continue;
 		dev = devclass_get_device(pcm_devclass, i);
-        	if (1) {
-			snprintf(buf + strlen(buf), size - strlen(buf),
-		            	"pcm%d: <%s> %s",
-		            	i, device_get_desc(dev), d->status);
-			if (d->chancount > 0)
-				snprintf(buf + strlen(buf), size - strlen(buf),
-				" (%dp/%dr channels%s)\n",
-			    	d->playcount, d->reccount,
-			    	(!(d->flags & SD_F_SIMPLEX))? " duplex" : "");
-			else
-				snprintf(buf + strlen(buf), size - strlen(buf),
-				" (mixer only)\n");
-		}
+		sbuf_printf(s, "pcm%d: <%s> %s", i, device_get_desc(dev), d->status);
+		if (d->chancount > 0) {
+			pc = rc = vc = 0;
+			SLIST_FOREACH(sce, &d->channels, link) {
+				c = sce->channel;
+				if (c->direction == PCMDIR_PLAY) {
+					if (c->flags & CHN_F_VIRTUAL)
+						vc++;
+					else
+						pc++;
+				} else
+					rc++;
+			}
+			sbuf_printf(s, " (%dp/%dr/%dv channels%s%s)\n", pc, rc, vc,
+					(d->flags & SD_F_SIMPLEX)? "" : " duplex",
+#ifdef USING_DEVFS
+					(i == snd_unit)? " default" : ""
+#else
+					""
+#endif
+					);
+#ifdef SNDSTAT_VERBOSE
+			SLIST_FOREACH(sce, &d->channels, link) {
+				c = sce->channel;
+				sbuf_printf(s, "\t%s[%s]: speed %d, format %08x, flags %08x",
+					c->parentchannel? c->parentchannel->name : "",
+					c->name, c->speed, c->format, c->flags);
+				if (c->pid != -1)
+					sbuf_printf(s, ", pid %d", c->pid);
+				sbuf_printf(s, "\n\t");
+				f = c->feeder;
+				while (f) {
+					sbuf_printf(s, "%s", f->class->name);
+					if (f->desc->type == FEEDER_FMT)
+						sbuf_printf(s, "(%08x <- %08x)", f->desc->out, f->desc->in);
+					if (f->desc->type == FEEDER_RATE)
+						sbuf_printf(s, "(%d <- %d)", FEEDER_GET(f, FEEDRATE_DST), FEEDER_GET(f, FEEDRATE_SRC));
+					if (f->desc->type == FEEDER_ROOT || f->desc->type == FEEDER_MIXER)
+						sbuf_printf(s, "(%08x)", f->desc->out);
+					if (f->source)
+						sbuf_printf(s, " <- ");
+					f = f->source;
+				}
+				sbuf_printf(s, "\n");
+			}
+#endif
+		} else
+			sbuf_printf(s, " (mixer only)\n");
     	}
-    	return strlen(buf);
+	sbuf_finish(s);
+    	return sbuf_len(s);
 }
 
 static int
-status_read(struct uio *buf)
+do_status(int action, struct uio *buf)
 {
-    	static char	status_buf[4096];
-    	static int 	bufptr = 0, buflen = 0;
-    	int l;
-
-    	if (status_isopen == 1) {
-		status_isopen++;
+	static struct sbuf s;
+    	static int bufptr = 0;
+	static int status_open = 0;
+    	int l, err;
+
+	switch(action) {
+	case 0: /* open */
+		if (status_open)
+			return EBUSY;
+		if (sbuf_new(&s, NULL, 4096, 0))
+			return ENXIO;
 		bufptr = 0;
-		buflen = status_init(status_buf, sizeof status_buf);
-    	}
+		err = (status_init(&s) > 0)? 0 : ENOMEM;
+		if (!err)
+			status_open = 1;
+		return err;
+
+	case 1: /* close */
+		if (!status_open)
+			return EBADF;
+		sbuf_delete(&s);
+		status_open = 0;
+		return 0;
+
+	case 2:
+		if (!status_open)
+			return EBADF;
+	    	l = min(buf->uio_resid, sbuf_len(&s) - bufptr);
+		err = (l > 0)? uiomove(sbuf_data(&s) + bufptr, l, buf) : 0;
+    		bufptr += l;
+    		return err;
+
+	case 3:
+		return status_open;
+	}
 
-    	l = min(buf->uio_resid, buflen - bufptr);
-    	bufptr += l;
-    	return (l > 0)? uiomove(status_buf + bufptr - l, l, buf) : 0;
+	return EBADF;
 }
 
 static int
@@ -731,7 +879,7 @@ sndpcm_modevent(module_t mod, int type, void *data)
 	case MOD_LOAD:
 		break;
 	case MOD_UNLOAD:
-		if (status_isopen)
+		if (do_status(3, NULL))
 			return EBUSY;
 		if (status_dev)
 			destroy_dev(status_dev);
diff --git a/sys/dev/sound/pcm/sound.h b/sys/dev/sound/pcm/sound.h
index 007285b..df6d729 100644
--- a/sys/dev/sound/pcm/sound.h
+++ b/sys/dev/sound/pcm/sound.h
@@ -98,12 +98,17 @@ struct snd_mixer;
 #include <dev/sound/pcm/mixer.h>
 #include <dev/sound/pcm/dsp.h>
 
+struct snddev_channel {
+	SLIST_ENTRY(snddev_channel) link;
+	struct pcm_channel *channel;
+};
+
 #define SND_STATUSLEN	64
 /* descriptor of audio device */
 struct snddev_info {
-	struct pcm_channel *play, *rec, **aplay, **arec, *fakechan;
-	int *ref;
-	unsigned playcount, reccount, chancount, maxchans;
+	SLIST_HEAD(, snddev_channel) channels;
+	struct pcm_channel **aplay, **arec, *fakechan;
+	unsigned chancount, maxchans;
 	struct snd_mixer *mixer;
 	unsigned flags;
 	void *devinfo;
@@ -193,6 +198,15 @@ int fkchan_kill(struct pcm_channel *c);
 
 SYSCTL_DECL(_hw_snd);
 
+struct pcm_channel *pcm_chnalloc(struct snddev_info *d, int direction);
+int pcm_chnfree(struct pcm_channel *c);
+int pcm_chnref(struct pcm_channel *c, int ref);
+
+struct pcm_channel *pcm_chn_create(struct snddev_info *d, struct pcm_channel *parent, kobj_class_t cls, int dir, void *devinfo);
+int pcm_chn_destroy(struct pcm_channel *ch);
+int pcm_chn_add(struct snddev_info *d, struct pcm_channel *ch);
+int pcm_chn_remove(struct snddev_info *d, struct pcm_channel *ch);
+
 int pcm_addchan(device_t dev, int dir, kobj_class_t cls, void *devinfo);
 int pcm_register(device_t dev, void *devinfo, int numplay, int numrec);
 int pcm_unregister(device_t dev);
diff --git a/sys/dev/sound/pcm/vchan.c b/sys/dev/sound/pcm/vchan.c
new file mode 100644
index 0000000..c96f0f3
--- /dev/null
+++ b/sys/dev/sound/pcm/vchan.c
@@ -0,0 +1,383 @@
+/*
+ * Copyright (c) 2001 Cameron Grant <gandalf@vilnya.demon.co.uk>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#include <dev/sound/pcm/sound.h>
+#include <dev/sound/pcm/vchan.h>
+#include "feeder_if.h"
+
+struct vchinfo {
+	u_int32_t spd, fmt, blksz, run;
+	struct pcm_channel *channel, *parent;
+	struct pcmchan_caps caps;
+};
+
+static u_int32_t vchan_fmt[] = {
+	AFMT_S16_LE,
+	AFMT_STEREO | AFMT_S16_LE,
+	0
+};
+
+
+static int
+vchan_mix_s16(int16_t *to, int16_t *tmp, unsigned int count)
+{
+	/*
+	 * to is the output buffer, tmp is the input buffer
+	 * count is the number of 16bit samples to mix
+	 */
+	int i;
+	int x;
+
+	for(i = 0; i < count; i++) {
+		x = to[i];
+		x += tmp[i];
+		if (x < -32768) {
+			/* printf("%d + %d = %d (u)\n", to[i], tmp[i], x); */
+			x = -32768;
+		}
+		if (x > 32767) {
+			/* printf("%d + %d = %d (o)\n", to[i], tmp[i], x); */
+			x = 32767;
+		}
+		to[i] = x & 0x0000ffff;
+	}
+	return 0;
+}
+
+static int
+feed_vchan_s16(struct pcm_feeder *f, struct pcm_channel *c, u_int8_t *b, u_int32_t count, void *source)
+{
+	/* we're going to abuse things a bit */
+	struct snd_dbuf *src = source;
+	struct pcmchan_children *cce;
+	struct pcm_channel *ch;
+	int16_t *tmp, *dst;
+	unsigned int cnt;
+
+	KASSERT(sndbuf_getsize(src) >= count, ("bad bufsize"));
+	count &= ~1;
+	bzero(b, count);
+
+	/*
+	 * we are going to use our source as a temporary buffer since it's
+	 * got no other purpose.  we obtain our data by traversing the channel
+	 * list of children and calling vchan_mix_* to mix count bytes from each
+	 * into our destination buffer, b
+	 */
+	dst = (int16_t *)b;
+	tmp = (int16_t *)sndbuf_getbuf(src);
+	bzero(tmp, count);
+	SLIST_FOREACH(cce, &c->children, link) {
+		ch = cce->channel;
+		cnt = FEEDER_FEED(ch->feeder, ch, (u_int8_t *)tmp, count, ch->bufsoft);
+		vchan_mix_s16(dst, tmp, cnt / 2);
+	}
+
+	return count;
+}
+
+static struct pcm_feederdesc feeder_vchan_s16_desc[] = {
+	{FEEDER_MIXER, AFMT_S16_LE, AFMT_S16_LE, 0},
+	{FEEDER_MIXER, AFMT_S16_LE | AFMT_STEREO, AFMT_S16_LE | AFMT_STEREO, 0},
+	{0},
+};
+static kobj_method_t feeder_vchan_s16_methods[] = {
+    	KOBJMETHOD(feeder_feed,		feed_vchan_s16),
+	{ 0, 0 }
+};
+FEEDER_DECLARE(feeder_vchan_s16, 2, NULL);
+
+/************************************************************/
+
+static void *
+vchan_init(kobj_t obj, void *devinfo, struct snd_dbuf *b, struct pcm_channel *c, int dir)
+{
+	struct vchinfo *ch;
+	struct pcm_channel *parent = devinfo;
+
+	KASSERT(dir == PCMDIR_PLAY, ("vchan_init: bad direction"));
+	ch = malloc(sizeof(*ch), M_DEVBUF, M_WAITOK | M_ZERO);
+	ch->parent = parent;
+	ch->channel = c;
+	ch->fmt = AFMT_U8;
+	ch->spd = DSP_DEFAULT_SPEED;
+	ch->blksz = 2048;
+
+	c->flags |= CHN_F_VIRTUAL;
+
+	return ch;
+}
+
+static int
+vchan_free(kobj_t obj, void *data)
+{
+	return 0;
+}
+
+static int
+vchan_setformat(kobj_t obj, void *data, u_int32_t format)
+{
+	struct vchinfo *ch = data;
+	struct pcm_channel *parent = ch->parent;
+
+	ch->fmt = format;
+	chn_notify(parent, CHN_N_FORMAT);
+	return 0;
+}
+
+static int
+vchan_setspeed(kobj_t obj, void *data, u_int32_t speed)
+{
+	struct vchinfo *ch = data;
+	struct pcm_channel *parent = ch->parent;
+
+	ch->spd = speed;
+	chn_notify(parent, CHN_N_RATE);
+	return speed;
+}
+
+static int
+vchan_setblocksize(kobj_t obj, void *data, u_int32_t blocksize)
+{
+	struct vchinfo *ch = data;
+	struct pcm_channel *parent = ch->parent;
+
+	ch->blksz = blocksize;
+	chn_notify(parent, CHN_N_BLOCKSIZE);
+	return blocksize;
+}
+
+static int
+vchan_trigger(kobj_t obj, void *data, int go)
+{
+	struct vchinfo *ch = data;
+	struct pcm_channel *parent = ch->parent;
+
+	if (go == PCMTRIG_EMLDMAWR || go == PCMTRIG_EMLDMARD)
+		return 0;
+
+	ch->run = (go == PCMTRIG_START)? 1 : 0;
+	chn_notify(parent, CHN_N_TRIGGER);
+
+	return 0;
+}
+
+static struct pcmchan_caps *
+vchan_getcaps(kobj_t obj, void *data)
+{
+	struct vchinfo *ch = data;
+
+	ch->caps.minspeed = sndbuf_getspd(ch->parent->bufhard);
+	ch->caps.maxspeed = ch->caps.minspeed;
+	ch->caps.fmtlist = vchan_fmt;
+	ch->caps.caps = 0;
+
+	return &ch->caps;
+}
+
+static kobj_method_t vchan_methods[] = {
+    	KOBJMETHOD(channel_init,		vchan_init),
+    	KOBJMETHOD(channel_free,		vchan_free),
+    	KOBJMETHOD(channel_setformat,		vchan_setformat),
+    	KOBJMETHOD(channel_setspeed,		vchan_setspeed),
+    	KOBJMETHOD(channel_setblocksize,	vchan_setblocksize),
+    	KOBJMETHOD(channel_trigger,		vchan_trigger),
+    	KOBJMETHOD(channel_getcaps,		vchan_getcaps),
+	{ 0, 0 }
+};
+CHANNEL_DECLARE(vchan);
+
+/* virtual channel interface */
+
+int
+vchan_create(struct pcm_channel *parent)
+{
+    	struct snddev_info *d = parent->parentsnddev;
+	struct pcmchan_children *pce;
+	struct pcm_channel *child;
+	int err, first;
+
+	if (!(parent->flags & CHN_F_BUSY))
+		return EBUSY;
+
+	pce = malloc(sizeof(*pce), M_DEVBUF, M_WAITOK | M_ZERO);
+	if (!pce)
+		return ENOMEM;
+
+	/* create a new playback channel */
+	child = pcm_chn_create(d, parent, &vchan_class, PCMDIR_VIRTUAL, parent);
+	if (!child) {
+		free(pce, M_DEVBUF);
+		return ENODEV;
+	}
+
+	first = SLIST_EMPTY(&parent->children);
+	/* add us to our parent channel's children */
+	pce->channel = child;
+	SLIST_INSERT_HEAD(&parent->children, pce, link);
+
+	/* add us to our grandparent's channel list */
+	err = pcm_chn_add(d, child);
+	if (err) {
+		pcm_chn_destroy(child);
+		free(pce, M_DEVBUF);
+	}
+
+	/* XXX gross ugly hack, kill murder death */
+	if (first && !err) {
+		err = chn_reset(parent, AFMT_STEREO | AFMT_S16_LE);
+		if (err)
+			printf("chn_reset: %d\n", err);
+		err = chn_setspeed(parent, 44100);
+		if (err)
+			printf("chn_setspeed: %d\n", err);
+	}
+
+	return err;
+}
+
+int
+vchan_destroy(struct pcm_channel *c)
+{
+	struct pcm_channel *parent = c->parentchannel;
+    	struct snddev_info *d = parent->parentsnddev;
+	struct pcmchan_children *pce;
+	int err;
+
+	if (!(parent->flags & CHN_F_BUSY))
+		return EBUSY;
+	if (SLIST_EMPTY(&parent->children))
+		return EINVAL;
+
+	/* remove us from our grantparent's channel list */
+	err = pcm_chn_remove(d, c);
+	if (err)
+		return err;
+
+	/* remove us from our parent's children list */
+	SLIST_FOREACH(pce, &parent->children, link) {
+		if (pce->channel == c)
+			goto gotch;
+	}
+	return EINVAL;
+gotch:
+	SLIST_REMOVE(&parent->children, pce, pcmchan_children, link);
+	free(pce, M_DEVBUF);
+
+	if (SLIST_EMPTY(&parent->children))
+		parent->flags &= ~CHN_F_BUSY;
+	/* destroy ourselves */
+	err = pcm_chn_destroy(c);
+
+	return err;
+}
+
+#ifdef SND_DYNSYSCTL
+static int
+sysctl_hw_snd_vchans(SYSCTL_HANDLER_ARGS)
+{
+	struct snddev_info *d;
+    	struct snddev_channel *sce;
+	struct pcm_channel *c;
+	int err, newcnt, cnt;
+
+	d = oidp->oid_arg1;
+
+	cnt = 0;
+	SLIST_FOREACH(sce, &d->channels, link) {
+		c = sce->channel;
+		if ((c->direction == PCMDIR_PLAY) && (c->flags & CHN_F_VIRTUAL))
+			cnt++;
+	}
+	newcnt = cnt;
+
+	err = sysctl_handle_int(oidp, &newcnt, sizeof(newcnt), req);
+	if (err == 0 && req->newptr != NULL) {
+		if (newcnt > cnt) {
+			/* add new vchans - find a parent channel first */
+			SLIST_FOREACH(sce, &d->channels, link) {
+				c = sce->channel;
+				/* not a candidate if not a play channel */
+				if (c->direction != PCMDIR_PLAY)
+					goto addskip;
+				/* not a candidate if a virtual channel */
+				if (c->flags & CHN_F_VIRTUAL)
+					goto addskip;
+				/* not a candidate if it's in use */
+				if ((c->flags & CHN_F_BUSY) && (SLIST_EMPTY(&c->children)))
+					goto addskip;
+				/*
+				 * if we get here we're a nonvirtual play channel, and either
+				 * 1) not busy
+				 * 2) busy with children, not directly open
+				 *
+				 * thus we can add children
+				 */
+				goto addok;
+addskip:
+			}
+			return EBUSY;
+addok:
+			c->flags |= CHN_F_BUSY;
+			while (err == 0 && newcnt > cnt) {
+				err = vchan_create(c);
+				if (err == 0)
+					cnt++;
+			}
+		} else if (newcnt < cnt) {
+			while (err == 0 && newcnt < cnt) {
+				SLIST_FOREACH(sce, &d->channels, link) {
+					c = sce->channel;
+					if ((c->flags & (CHN_F_BUSY | CHN_F_VIRTUAL)) == CHN_F_VIRTUAL)
+						goto remok;
+				}
+				return EINVAL;
+remok:
+				err = vchan_destroy(c);
+				if (err == 0)
+					cnt--;
+			}
+		}
+	}
+
+	return err;
+}
+#endif
+
+int
+vchan_initsys(struct snddev_info *d)
+{
+#ifdef SND_DYNSYSCTL
+	SYSCTL_ADD_PROC(&d->sysctl_tree, SYSCTL_CHILDREN(d->sysctl_tree_top),
+            OID_AUTO, "vchans", CTLTYPE_INT | CTLFLAG_RW, d, sizeof(d),
+	    sysctl_hw_snd_vchans, "I", "")
+#endif
+	return 0;
+}
+
+
diff --git a/sys/dev/sound/pcm/vchan.h b/sys/dev/sound/pcm/vchan.h
new file mode 100644
index 0000000..7e057ce
--- /dev/null
+++ b/sys/dev/sound/pcm/vchan.h
@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2001 Cameron Grant <gandalf@vilnya.demon.co.uk>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+int vchan_create(struct pcm_channel *parent);
+int vchan_destroy(struct pcm_channel *c);
+int vchan_initsys(struct snddev_info *d);
+
+