X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=afh_common.c;h=b06e4eb5a0ef16653476e61574e55ad6878efbe7;hp=5be43550c202b516aaedf332dbbfba341da20dcb;hb=093dda1824631372587d107d64601389027c6187;hpb=8bcf75a3921d15e03c4351b3efa609eac67c3817

diff --git a/afh_common.c b/afh_common.c
index 5be43550..b06e4eb5 100644
--- a/afh_common.c
+++ b/afh_common.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1997-2013 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 1997-2014 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
@@ -230,11 +230,12 @@ success:
 }
 
 /**
- * Deallocate contents of a filled-in ahi structure
+ * Deallocate the contents of an afh_info structure.
  *
  * \param afhi The structure to clear.
  *
- * The given pointer is kept, everything else is freed.
+ * This only frees the memory the various pointer fields of \a afhi point to.
+ * It does *not* free \a afhi itself.
  */
 void clear_afhi(struct afh_info *afhi)
 {
@@ -264,6 +265,12 @@ 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 +288,28 @@ 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;
 }
 
 /**