+/**
+ * Print help text of each filter to stdout.
+ *
+ * \param flags Passed to \ref ggo_print_help().
+ */
+void print_filter_helps(unsigned flags)
+{
+ int i, num = 0;
+
+ printf_or_die("\nAvailable filters: ");
+ FOR_EACH_SUPPORTED_FILTER(i) {
+ if (num > 50) {
+ printf_or_die("\n ");
+ num = 0;
+ }
+ num += printf_or_die("%s%s", i? " " : "", filter_get(i)->name);
+ }
+ printf_or_die("\n");
+
+ FOR_EACH_SUPPORTED_FILTER(i) {
+ struct filter *f = (struct filter *)filter_get(i);
+
+ if (!f->help.short_help)
+ continue;
+ printf_or_die("\nOptions for %s (%s):", f->name,
+ f->help.purpose);
+ ggo_print_help(&f->help, flags);
+ }
+}
+
+/**
+ * Set select timeout of the scheduler.
+ *
+ * \param s The scheduler.
+ * \param context Pointer to the filter node (task context).
+ *
+ * This looks at the status of the btr node of the filter. If data is available
+ * in the input queue of the filter, or if an error occurred, a minimal timeout
+ * for the next select call is requested from the scheduler. Otherwise the
+ * scheduler timeout is left unchanged.
+ */
+void generic_filter_pre_select(struct sched *s, void *context)
+{
+ struct filter_node *fn = context;
+
+ if (btr_node_status(fn->btrn, fn->min_iqs, BTR_NT_INTERNAL) != 0)
+ sched_min_delay(s);
+}
+
+#ifdef WORDS_BIGENDIAN
+#define DECODER_SAMPLE_FORMAT SF_S16_BE
+#else
+#define DECODER_SAMPLE_FORMAT SF_S16_LE
+#endif
+
+/**
+ * Execute a btr command for a decoder.
+ *
+ * The buffer tree nodes of the writers ask the parent nodes about sample_rate,
+ * channels count and sample format. This function is called by all decoders to
+ * answer these queries.
+ *
+ * \param cmd The command to be executed by the child node.
+ * \param sample_rate Known to the decoder.
+ * \param channels Known to the decoder.
+ * \param result Ascii representation on the answer is stored here.
+ *
+ * \return Standard.
+ */
+int decoder_execute(const char *cmd, unsigned sample_rate, unsigned channels,
+ char **result)
+{
+ if (!strcmp(cmd, "sample_rate")) {
+ if (sample_rate == 0)
+ return -E_BTR_NAVAIL;
+ *result = make_message("%u", sample_rate);
+ return 1;
+ }
+ if (!strcmp(cmd, "channels")) {
+ if (channels == 0)
+ return -E_BTR_NAVAIL;
+ *result = make_message("%u", channels);
+ return 1;
+ }
+ if (!strcmp(cmd, "sample_format")) {
+ *result = make_message("%u", DECODER_SAMPLE_FORMAT);
+ return 1;
+ }
+ return -ERRNO_TO_PARA_ERROR(ENOTSUP);
+}