X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=oss_write.c;h=35f7b6280115ec53bf88d5f2e303e34f8cc45d98;hp=3c61a445eec2456ec5fdcf585a9d95753d4cd71c;hb=d1e7875caba9aface190dab0de394435a80edd21;hpb=650e5374914c1eb725ce7d2a720611bec22112bc

diff --git a/oss_write.c b/oss_write.c
index 3c61a445..35f7b628 100644
--- a/oss_write.c
+++ b/oss_write.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2009-2013 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2009-2014 Andre Noll <maan@tuebingen.mpg.de>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
@@ -31,6 +31,29 @@ struct private_oss_write_data {
 	int bytes_per_frame;
 };
 
+/*
+ * We keep one bit of static storage to make sure only one instance of the oss
+ * writer is running at any given time.
+ */
+static bool sound_device_busy;
+
+static bool sound_device_is_busy(void)
+{
+	return sound_device_busy;
+}
+
+static void set_sound_device_busy(void)
+{
+	assert(!sound_device_busy);
+	sound_device_busy = true;
+}
+
+static void set_sound_device_idle(void)
+{
+	assert(sound_device_busy);
+	sound_device_busy = false;
+}
+
 static int get_oss_format(enum sample_format sf)
 {
 	switch (sf) {
@@ -44,13 +67,13 @@ static int get_oss_format(enum sample_format sf)
 	}
 }
 
-static void oss_pre_select(struct sched *s, struct task *t)
+static void oss_pre_select(struct sched *s, void *context)
 {
-	struct writer_node *wn = container_of(t, struct writer_node, task);
+	struct writer_node *wn = context;
 	struct private_oss_write_data *powd = wn->private_data;
 	int ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
 
-	if (ret == 0)
+	if (ret == 0 || (sound_device_is_busy() && !powd))
 		return;
 	if (ret < 0 || !powd)
 		return sched_min_delay(s);
@@ -65,6 +88,7 @@ static void oss_close(struct writer_node *wn)
 		return;
 	close(powd->fd);
 	free(powd);
+	set_sound_device_idle();
 }
 
 /*
@@ -157,17 +181,17 @@ err_free:
 	return ret;
 }
 
-static int oss_post_select(__a_unused struct sched *s,
-		struct task *t)
+static int oss_post_select(__a_unused struct sched *s, void *context)
 {
-	struct writer_node *wn = container_of(t, struct writer_node, task);
+	struct writer_node *wn = context;
 	struct private_oss_write_data *powd = wn->private_data;
 	struct btr_node *btrn = wn->btrn;
 	size_t frames, bytes;
 	int ret;
 	char *data;
+	audio_buf_info abi;
 
-	ret = task_get_notification(t);
+	ret = task_get_notification(wn->task);
 	if (ret < 0)
 		goto out;
 	ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
@@ -175,12 +199,16 @@ static int oss_post_select(__a_unused struct sched *s,
 		goto out;
 	if (!powd) {
 		int32_t rate, ch, format;
+
+		if (sound_device_is_busy())
+			return 0;
 		get_btr_sample_rate(btrn, &rate);
 		get_btr_channels(btrn, &ch);
 		get_btr_sample_format(btrn, &format);
 		ret = oss_init(wn, rate, ch, format);
 		if (ret < 0)
 			goto out;
+		set_sound_device_busy();
 		return 0;
 	}
 	btr_merge(btrn, wn->min_iqs);
@@ -193,6 +221,15 @@ static int oss_post_select(__a_unused struct sched *s,
 	ret = 0;
 	if (!FD_ISSET(powd->fd, &s->wfds))
 		goto out;
+	/* get maximal number of bytes that can be written */
+	ret = ioctl(powd->fd, SNDCTL_DSP_GETOSPACE, &abi);
+	if (ret >= 0) {
+		size_t max_frames = abi.bytes / powd->bytes_per_frame;
+		if (max_frames == 0)
+			goto out;
+		/* cap number of frames to avoid sound artefacts */
+		frames = PARA_MIN(frames, max_frames);
+	}
 	ret = xwrite(powd->fd, data, frames * powd->bytes_per_frame);
 	if (ret < 0)
 		goto out;