afh: Dynamic chunks.

[paraslash.git] / afh_common.c

diff --git a/afh_common.c b/afh_common.c
index 75d8b5118db91586d46f339fff0d1d1f693dfc07..a1021ee57a2fd67f0192a8049cfa512ecd5629d3 100644 (file)
--- a/afh_common.c
+++ b/afh_common.c
@@ -109,6 +109,11 @@ void afh_init(void)
        }
 }
 
+static bool afh_supports_dynamic_chunks(int audio_format_id)
+{
+       return afl[audio_format_id].get_chunk;
+}
+
 /**
  * Guess the audio format judging from filename.
  *
@@ -261,21 +266,73 @@ static inline size_t get_chunk_len(long unsigned chunk_num,
 /**
  * Get one chunk of audio data.
  *
+ * This implicitly calls the ->open method of the audio format handler at the
+ * first call.
+ *
  * \param chunk_num The number of the chunk to get.
  * \param afhi Describes the audio file.
+ * \param audio_format_id Determines the afh.
  * \param map The memory mapped audio file.
+ * \param mapsize Passed to the afh's ->open() method.
  * \param buf Result pointer.
  * \param len The length of the chunk in bytes.
+ * \param afh_context Value/result, determines whether ->open() is called.
  *
  * Upon return, \a buf will point so memory inside \a map. The returned buffer
  * must therefore not be freed by the caller.
+ *
+ * \return Standard.
  */
-void afh_get_chunk(long unsigned chunk_num, struct afh_info *afhi,
-               void *map, const char **buf, size_t *len)
+__must_check int afh_get_chunk(long unsigned chunk_num, struct afh_info *afhi,
+               uint8_t audio_format_id, const void *map, size_t mapsize,
+               const char **buf, size_t *len, void **afh_context)
 {
-       size_t pos = afhi->chunk_table[chunk_num];
-       *buf = map + pos;
-       *len = get_chunk_len(chunk_num, afhi);
+       struct audio_format_handler *afh = afl + audio_format_id;
+
+       if (afh_supports_dynamic_chunks(audio_format_id)) {
+               int ret;
+
+               if (!*afh_context) {
+                       ret = afh->open(map, mapsize, afh_context);
+                       if (ret < 0)
+                               return ret;
+               }
+               ret = afl[audio_format_id].get_chunk(chunk_num, *afh_context,
+                       buf, len);
+               if (ret < 0) {
+                       afh->close(*afh_context);
+                       *afh_context = NULL;
+               }
+               return ret;
+       } else {
+               size_t pos = afhi->chunk_table[chunk_num];
+               *buf = map + pos;
+               *len = get_chunk_len(chunk_num, afhi);
+               return 0;
+       }
+}
+
+/**
+ * Deallocate resources allocated due to dynamic chunk handling.
+ *
+ * This function should be called if afh_get_chunk() was called at least once.
+ * It is OK to call it even for audio formats which do not support dynamic
+ * chunks, in which case the function does nothing.
+ *
+ * \param afh_context As returned from the ->open method of the afh.
+ * \param audio_format_id Determines the afh.
+ */
+void afh_close(void *afh_context, uint8_t audio_format_id)
+{
+       struct audio_format_handler *afh = afl + audio_format_id;
+
+       if (!afh_supports_dynamic_chunks(audio_format_id))
+               return;
+       if (!afh->close)
+               return;
+       if (!afh_context)
+               return;
+       afh->close(afh_context);
 }
 
 /**
@@ -283,16 +340,22 @@ void afh_get_chunk(long unsigned chunk_num, struct afh_info *afhi,
  *
  * \param approx_chunk_num Upper bound for the chunk number to return.
  * \param afhi Needed for the chunk table.
+ * \param audio_format_id Determines the afh.
  *
- * \return The first non-empty chunk <= \a approx_chunk_num.
+ * \return For audio format handlers which support dynamic chunks, the function
+ * returns the given chunk number. Otherwise it returns 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)
+               const struct afh_info *afhi, uint8_t audio_format_id)
 {
        int32_t k;
 
+       if (afh_supports_dynamic_chunks(audio_format_id))
+               return approx_chunk_num;
+
        for (k = PARA_MAX(0, approx_chunk_num); k >= 0; k--)
                if (get_chunk_len(k, afhi) > 0)
                        return k;