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.

1 files changed, 383 insertions, 0 deletions

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;
+}
+
+