X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=afh_common.c;h=c5a25e36bfe889d22318fa28e5cf23088c2cbb67;hp=cad972d94026eb1f1587fdf7201b752786b801b7;hb=9c1aa53f0cda586aa13a022452d16a2704055578;hpb=c341594d9788fd7e52a76f6430d91fce41cbf0ec

diff --git a/afh_common.c b/afh_common.c
index cad972d9..c5a25e36 100644
--- a/afh_common.c
+++ b/afh_common.c
@@ -264,6 +264,12 @@ const char *audio_format_name(int i)
 	return afl[i].name;
 }
 
+static inline size_t get_chunk_len(long unsigned chunk_num,
+		const struct afh_info *afhi)
+{
+	return afhi->chunk_table[chunk_num + 1] - afhi->chunk_table[chunk_num];
+}
+
 /**
  * Get one chunk of audio data.
  *
@@ -281,7 +287,28 @@ void afh_get_chunk(long unsigned chunk_num, struct afh_info *afhi,
 {
 	size_t pos = afhi->chunk_table[chunk_num];
 	*buf = map + pos;
-	*len = afhi->chunk_table[chunk_num + 1] - pos;
+	*len = get_chunk_len(chunk_num, afhi);
+}
+
+/**
+ * Find a suitable start chunk.
+ *
+ * \param approx_chunk_num Upper bound for the chunk number to return.
+ * \param afhi Needed for the chunk table.
+ *
+ * \return The first non-empty chunk <= \a approx_chunk_num.
+ *
+ * \sa \ref afh_get_chunk().
+ */
+int32_t afh_get_start_chunk(int32_t approx_chunk_num,
+		const struct afh_info *afhi)
+{
+	int32_t k;
+
+	for (k = PARA_MAX(0, approx_chunk_num); k >= 0; k--)
+		if (get_chunk_len(k, afhi) > 0)
+			break;
+	return k;
 }
 
 /**