buflib: Try harder in buflib_alloc_maximum().

This function will now ask shrinkable allocations to give up all of their
memory. With future support of playback.c this can be used as a safe
replacement for audio_get_buffer().

Change-Id: I290a51d2c75254e66baf5698c41dc444dea6247a

1 files changed, 5 insertions, 3 deletions

diff --git a/firmware/include/buflib.h b/firmware/include/buflib.h
index 7183951c6c..aa6c232f72 100644
--- a/firmware/include/buflib.h
+++ b/firmware/include/buflib.h
@@ -111,10 +111,10 @@ struct buflib_callbacks {
     void (*sync_callback)(int handle, bool sync_on);
 };
 
-#define BUFLIB_SHRINK_POS_MASK ((1<<0|1<<1)<<30)
 #define BUFLIB_SHRINK_SIZE_MASK (~BUFLIB_SHRINK_POS_MASK)
 #define BUFLIB_SHRINK_POS_FRONT (1u<<31)
 #define BUFLIB_SHRINK_POS_BACK  (1u<<30)
+#define BUFLIB_SHRINK_POS_MASK  (BUFLIB_SHRINK_POS_FRONT|BUFLIB_SHRINK_POS_BACK)
 
 /**
  * Possible return values for the callbacks, some of them can cause
@@ -193,8 +193,10 @@ int buflib_alloc_ex(struct buflib_context *ctx, size_t size, const char *name,
  * will allow buflib to permit allocations by shrinking the buffer returned by
  * this function.
  *
- * Note that this currently gives whatever buflib_available() returns. However,
- * do not depend on this behavior, it may change.
+ * Note that this might return many more bytes than buflib_available() or
+ * buflib_allocatable() return, because it agressively compacts the pool
+ * and even shrinks other allocations. However, do not depend on this behavior,
+ * it may change.
  *
  * name: A string identifier giving this allocation a name
  * size: The actual size will be returned into size