Soft volume implementation for audio devices without pcm mixer controller.

Submitted by:	Ariff Abdullah <skywizard@MyBSD.org.my>
Tested by:	multimedia@

3 files changed, 80 insertions, 1 deletions

diff --git a/sys/conf/files b/sys/conf/files
index eae581a..1af4da6 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -882,6 +882,7 @@ dev/sound/pcm/feeder.c		optional sound
 dev/sound/pcm/feeder_fmt.c	optional sound
 dev/sound/pcm/feeder_if.m	optional sound
 dev/sound/pcm/feeder_rate.c	optional sound
+dev/sound/pcm/feeder_volume.c	optional sound
 dev/sound/pcm/mixer.c		optional sound
 dev/sound/pcm/mixer_if.m	optional sound
 dev/sound/pcm/sndstat.c		optional sound
diff --git a/sys/dev/sound/pcm/feeder_volume.c b/sys/dev/sound/pcm/feeder_volume.c
new file mode 100644
index 0000000..378c793
--- /dev/null
+++ b/sys/dev/sound/pcm/feeder_volume.c
@@ -0,0 +1,78 @@
+/*-
+ * Copyright (c) 2005 Ariff Abdullah 
+ *        <skywizard@MyBSD.org.my> 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.
+ *
+ * feeder_volume, a long 'Lost Technology' rather than a new feature.
+ */
+
+#include <dev/sound/pcm/sound.h>
+#include "feeder_if.h"
+
+SND_DECLARE_FILE("$FreeBSD$");
+
+static int
+feed_volume_s16(struct pcm_feeder *f, struct pcm_channel *c, uint8_t *b,
+		uint32_t count, void *source)
+{
+	int i, j, k, vol[2];
+	int16_t *buf;
+
+	k = FEEDER_FEED(f->source, c, b, count & ~1, source);
+	if (k < 2) {
+#if 0
+		device_printf(c->dev, "%s: Not enough data (Got: %d bytes)\n",
+				__func__, k);
+#endif
+		return 0;
+	}
+#if 0
+	if (k & 1)
+		device_printf(c->dev, "%s: Bytes not 16bit aligned.\n", __func__);
+#endif
+	k &= ~1;
+	i = k >> 1;
+	buf = (int16_t *)b;
+	vol[0] = c->volume & 0x7f;
+	vol[1] = (c->volume >> 8) & 0x7f;
+	while (i > 0) {
+		i--;
+		j = (vol[i & 1] * buf[i]) / 100;
+		if (j > 32767)
+			j = 32767;
+		if (j < -32768)
+			j = -32768;
+		buf[i] = j;
+	}
+	return k;
+}
+
+static struct pcm_feederdesc feeder_volume_s16_desc[] = {
+	{FEEDER_VOLUME, AFMT_S16_LE|AFMT_STEREO, AFMT_S16_LE|AFMT_STEREO, 0},
+	{0, 0, 0, 0},
+};
+static kobj_method_t feeder_volume_s16_methods[] = {
+    	KOBJMETHOD(feeder_feed, feed_volume_s16),
+	{0, 0}
+};
+FEEDER_DECLARE(feeder_volume_s16, 2, NULL);
diff --git a/sys/modules/sound/sound/Makefile b/sys/modules/sound/sound/Makefile
index 8649d96..08c883d 100644
--- a/sys/modules/sound/sound/Makefile
+++ b/sys/modules/sound/sound/Makefile
@@ -8,7 +8,7 @@ SRCS=	device_if.h bus_if.h isa_if.h pci_if.h opt_isa.h
 SRCS+=	ac97_if.h channel_if.h feeder_if.h mixer_if.h
 SRCS+=	ac97_if.c channel_if.c feeder_if.c mixer_if.c
 SRCS+=	ac97.c ac97_patch.c buffer.c channel.c dsp.c
-SRCS+=	fake.c feeder.c feeder_fmt.c feeder_rate.c
+SRCS+=	fake.c feeder.c feeder_fmt.c feeder_rate.c feeder_volume.c
 SRCS+=	mixer.c sndstat.c sound.c vchan.c
 
 EXPORT_SYMS=	YES	# XXX evaluate