Buflib: Make shrinking and buflib_available() smarter.

* shrinking now considers freespace just before the alloc-to-be-shrinked,
  that means less (or sometimes none at all) is taken from the audio buffer.
* core_available() now searches for the best free space, instead of simply the end,
  i.e. it will not return 0 if the audio buffer is allocated and there's free space
  before it. It also runs a compaction to ensure maximum contiguous memory.

audio_buffer_available() is also enhanced. It now considers the 256K reserve buffer,
and returns free buflib space instead if the audio buffer is short.

This all fixes the root problem of FS#12344 (Sansa Clip+: PANIC occurred when
dircache is enabled), that alloced from the audio buffer, even if it was very
short and buflib had many more available as free space before it.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@31006 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 4 insertions, 0 deletions

diff --git a/firmware/export/audio.h b/firmware/export/audio.h
index 57f3c24aae..5309ddd1d1 100644
--- a/firmware/export/audio.h
+++ b/firmware/export/audio.h
@@ -58,6 +58,10 @@ void audio_resume(void);
 void audio_next(void);
 void audio_prev(void);
 int audio_status(void);
+/* size of the audio buffer */
+size_t audio_buffer_size(void);
+/* size of the buffer available for allocating memory from the audio buffer using core_*()
+ * returns core_available() if audio buffer is not allocated yet */
 size_t audio_buffer_available(void);
 void audio_ff_rewind(long newpos);
 void audio_flush_and_reload_tracks(void);