X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=alsa_write.c;h=047e88f2200a45f2518c7f1508874108e26a6bce;hp=34a71f9bd34b503fafdbb192d5479c1815846b49;hb=a7a72ca4acf7f44abca866d410e2bc80590e7fab;hpb=5ff2b0b3a6f9242033c436fb8272245f5594dd8c

diff --git a/alsa_write.c b/alsa_write.c
index 34a71f9b..047e88f2 100644
--- a/alsa_write.c
+++ b/alsa_write.c
@@ -52,6 +52,8 @@ struct private_alsa_write_data {
 	 */
 	unsigned channels;
 	struct timeval drain_barrier;
+	/* File descriptor for select(). */
+	int poll_fd;
 };
 
 static snd_pcm_format_t get_alsa_pcm_format(enum sample_format sf)
@@ -143,11 +145,13 @@ static int alsa_init(struct private_alsa_write_data *pad,
 
 static void alsa_write_pre_select(struct sched *s, struct task *t)
 {
+	struct pollfd pfd;
 	struct writer_node *wn = container_of(t, struct writer_node, task);
 	struct private_alsa_write_data *pad = wn->private_data;
-	snd_pcm_sframes_t avail, underrun;
 	int ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
 
+	if (pad)
+		pad->poll_fd = -1;
 	if (ret == 0)
 		return;
 	if (!pad) {
@@ -158,25 +162,14 @@ static void alsa_write_pre_select(struct sched *s, struct task *t)
 		sched_request_barrier_or_min_delay(&pad->drain_barrier, s);
 		return;
 	}
-	/*
-	 * Data is available to be written to the alsa handle.  Compute number
-	 * of milliseconds until next buffer underrun would occur.
-	 *
-	 * snd_pcm_avail_update() updates the current available count of
-	 * samples for writing.  It is a light method to obtain current stream
-	 * position, because it does not require the user <-> kernel context
-	 * switch, but the value is less accurate, because ring buffer pointers
-	 * are updated in kernel drivers only when an interrupt occurs.
-	 */
-	avail = snd_pcm_avail_update(pad->handle);
-	if (avail < 0)
-		avail = 0;
-	underrun = (pad->buffer_frames - avail) * pad->buffer_time
-		/ pad->buffer_frames / 1000;
-	if (underrun < 50)
-		underrun = 50;
-	underrun -= 50;
-	sched_request_timeout_ms(underrun, s);
+	ret = snd_pcm_poll_descriptors(pad->handle, &pfd, 1);
+	if (ret < 0) {
+		PARA_ERROR_LOG("%s\n", snd_strerror(-ret));
+		t->error = -E_ALSA_POLL_FDS;
+		return;
+	}
+	pad->poll_fd = pfd.fd;
+	para_fd_set(pfd.fd, &s->rfds, &s->max_fileno);
 }
 
 static void alsa_close(struct writer_node *wn)
@@ -255,6 +248,8 @@ again:
 		wn->min_iqs = pad->bytes_per_frame;
 		goto again;
 	}
+	if (pad->poll_fd >= 0 && !FD_ISSET(pad->poll_fd, &s->rfds))
+		return;
 	frames = bytes / pad->bytes_per_frame;
 	frames = snd_pcm_writei(pad->handle, data, frames);
 	if (frames == 0 || frames == -EAGAIN)
@@ -280,7 +275,6 @@ __malloc static void *alsa_parse_config_or_die(const char *options)
 {
 	struct alsa_write_args_info *conf = para_calloc(sizeof(*conf));
 
-	PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
 	/* exits on errors */
 	alsa_cmdline_parser_string(options, conf, "alsa_write");
 	return conf;