X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=check_wav.c;h=a36cea9ab34fb319bf7070eaa43e8bb65dcfcd24;hp=12f44b5be4efb032ba6db054764d108b987cb58c;hb=5f511d41a111aa04189b32fd77d02e16f90ff2cc;hpb=216399fa29e2c071cd4485c57b6b1c9f4a74057b

diff --git a/check_wav.c b/check_wav.c
index 12f44b5b..a36cea9a 100644
--- a/check_wav.c
+++ b/check_wav.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2005-2012 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2005-2014 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
@@ -19,9 +19,13 @@
 /** Length of a standard wav header. */
 #define WAV_HEADER_LEN 44
 
+/** The possible states of a check_wav instance. */
 enum check_wav_state {
+	/** Initial state, less than \p WAV_HEADER_LEN bytes available. */
 	CWS_NEED_HEADER,
+	/** Wav hader was detected. */
 	CWS_HAVE_HEADER,
+	/** First part of the stream did not look like a wav header. */
 	CWS_NO_HEADER,
 };
 
@@ -37,6 +41,15 @@ struct check_wav_context {
 	unsigned sample_rate;
 };
 
+/**
+ * Set select timeout according to the given context.
+ *
+ * \param s Contains the timeval that should be set.
+ * \param cwc Contains a pointer to the buffer tree node.
+ *
+ * This requests a minimal timeout from the scheduler if btrn of \a cwc is not
+ * idle.
+ */
 void check_wav_pre_select(struct sched *s, struct check_wav_context *cwc)
 {
 	int ret = btr_node_status(cwc->btrn, cwc->min_iqs, BTR_NT_INTERNAL);
@@ -77,6 +90,13 @@ out:
 			val = header_val;
 			break;
 		case CWS_NO_HEADER:
+			/*
+			 * No wav header available and no value specified at
+			 * the command line. Maybe one of our parent nodes
+			 * knows.
+			 */
+			if (btr_exec_up(btr_parent(cwc->btrn), cmd, result) >= 0)
+				return 1;
 			/* Use default value */
 			val = arg;
 			break;
@@ -88,6 +108,22 @@ out:
 	return 1;
 }
 
+/**
+ * Filter out the wav header, pushdown everything else.
+ *
+ * \param cwc The context of this instance.
+ *
+ * This function looks at the first \p WAV_HEADER_SIZE bytes of the input queue
+ * of the btrn of \a cwc. If they look like a wav header, the function extracts
+ * the information of interest and swallows this part of the stream. Otherwise
+ * it is pushed down to all children. In either case the rest of the input is
+ * pushed down as well.
+ *
+ * Once the first part has been processed this way, the state of the instance
+ * changes from \p CWS_NEED_HEADER to \p CWS_HAVE_HEADER or \p CWS_NO_HEADER.
+ *
+ * \return Standard.
+ */
 int check_wav_post_select(struct check_wav_context *cwc)
 {
 	struct btr_node *btrn = cwc->btrn;
@@ -97,6 +133,8 @@ int check_wav_post_select(struct check_wav_context *cwc)
 	uint16_t bps; /* bits per sample */
 	const char *sample_formats[] = {SAMPLE_FORMATS};
 
+	if (!btrn)
+		return 0;
 	ret = btr_node_status(btrn, cwc->min_iqs, BTR_NT_INTERNAL);
 	if (ret <= 0)
 		goto out;
@@ -151,8 +189,26 @@ out:
 	return ret;
 }
 
+/**
+ * Allocate and set up a new check_wav instance.
+ *
+ * \param parent This buffer tree node will be the parent of the new node.
+ * \param child The child of the new node.
+ * \param params Default values and options.
+ * \param cw_btrn A pointer to the check wav node is returned here.
+ *
+ * This function also sets up the ->execute handler of the btrn so that all
+ * children of this node can figure out channel count, sample rate, etc.
+ *
+ * \return The (opaque) handle of the newly created check_wav instance. It is
+ * supposed to be passed to \ref check_wav_pre_select() and \ref
+ * check_wav_post_select().
+ *
+ * \sa \ref btr_new_node.
+ */
 struct check_wav_context *check_wav_init(struct btr_node *parent,
-		struct wav_params *params, struct btr_node **cw_btrn)
+		struct btr_node *child, struct wav_params *params,
+		struct btr_node **cw_btrn)
 {
 	struct check_wav_context *cwc = para_calloc(sizeof(*cwc));
 
@@ -160,13 +216,21 @@ struct check_wav_context *check_wav_init(struct btr_node *parent,
 	cwc->min_iqs = WAV_HEADER_LEN;
 	cwc->params = *params;
 	cwc->btrn = btr_new_node(&(struct btr_node_description)
-		EMBRACE(.name = "check_wav", .parent = parent,
+		EMBRACE(.name = "check_wav", .parent = parent, .child = child,
 		.handler = check_wav_exec, .context = cwc));
 	if (cw_btrn)
 		*cw_btrn = cwc->btrn;
 	return cwc;
 }
 
+/**
+ * Dellocate all ressources of a check_wav instance.
+ *
+ * \param cwc Determines the instance to shut down.
+ *
+ * This function may only be called after check_wav_post_select() has returned
+ * negative.
+ */
 void check_wav_shutdown(struct check_wav_context *cwc)
 {
 	free(cwc);