+/**
+ * Get one chunk of audio data.
+ *
+ * \param chunk_num The number of the chunk to get.
+ * \param afhi Describes the audio file.
+ * \param map The memory mapped audio file.
+ * \param buf Result pointer.
+ * \param len The length of the chunk in bytes.
+ *
+ * Upon return, \a buf will point so memory inside \a map. The returned buffer
+ * must therefore not be freed by the caller.
+ */
+void afh_get_chunk(long unsigned chunk_num, struct afh_info *afhi,
+ void *map, const char **buf, size_t *len)
+{
+ size_t pos = afhi->chunk_table[chunk_num];
+ *buf = map + pos;
+ *len = afhi->chunk_table[chunk_num + 1] - pos;
+}
+
+/**
+ * Get the header of an audio file.
+ *
+ * \param afhi The audio file handler data describing the file.
+ * \param audio_format_id Determines the audio format handler.
+ * \param map The data of the audio file.
+ * \param mapsize The amount of bytes of the mmapped audio file.
+ * \param buf The length of the header is stored here.
+ * \param len Points to a buffer containing the header on return.
+ *
+ * This function sets \a buf to \p NULL and \a len to zero if \a map or \a
+ * afhi is \p NULL, or if the current audio format does not need special
+ * header treatment.
+ *
+ * Otherwise, it is checked whether the audio format handler given by
+ * \a audio_format_id defines a ->get_header() method. If it does, this
+ * method is called to obtain the header. If ->get_header() is \p NULL,
+ * a reference to the first chunk of the audio file is returned.
+ *
+ * Once the header is no longer needed, the caller must call \ref
+ * afh_free_header() to free the resources allocated by this function.
+ */
+void afh_get_header(struct afh_info *afhi, uint8_t audio_format_id,
+ void *map, size_t mapsize, char **buf, size_t *len)
+{
+ struct audio_format_handler *afh = afl + audio_format_id;
+
+ if (!map || !afhi || !afhi->header_len) {
+ *buf = NULL;
+ *len = 0;
+ return;
+ }
+ if (!afh->get_header) {
+ *len = afhi->header_len;
+ *buf = map;
+ return;
+ }
+ afh->get_header(map, mapsize, buf, len);
+}
+
+/**
+ * Deallocate any resources obtained from afh_get_header().
+ *
+ * \param header_buf Pointer obtained via afh_get_header().
+ * \param audio_format_id Determines the audio format handler.
+ */
+void afh_free_header(char *header_buf, uint8_t audio_format_id)
+{
+ struct audio_format_handler *afh = afl + audio_format_id;
+
+ if (afh->get_header)
+ free(header_buf);
+}