Added SDL_ReserveSpaceInDataQueue() to make space without copying data.

1 files changed, 15 insertions, 0 deletions

diff --git a/src/SDL_dataqueue.h b/src/SDL_dataqueue.h
index d7d2697e9c..a5e3e1c60e 100644
--- a/src/SDL_dataqueue.h
+++ b/src/SDL_dataqueue.h
@@ -33,6 +33,21 @@ int SDL_WriteToDataQueue(SDL_DataQueue *queue, const void *data, const size_t le
 size_t SDL_ReadFromDataQueue(SDL_DataQueue *queue, void *buf, const size_t len);
 size_t SDL_CountDataQueue(SDL_DataQueue *queue);
 
+/* this sets a section of the data queue aside (possibly allocating memory for it)
+   as if it's been written to, but returns a pointer to that space. You may write
+   to this space until a read would consume it. Writes (and other calls to this
+   function) will safely append their data after this reserved space and can
+   be in flight at the same time. There is no thread safety.
+   If there isn't an existing block of memory that can contain the reserved
+   space, one will be allocated for it. You can not (currently) allocate
+   a space larger than the packetlen requested in SDL_NewDataQueue.
+   Returned buffer is uninitialized.
+   This lets you avoid an extra copy in some cases, but it's safer to use
+   SDL_WriteToDataQueue() unless you know what you're doing.
+   Returns pointer to buffer of at least (len) bytes, NULL on error.
+*/
+void *SDL_ReserveSpaceInDataQueue(SDL_DataQueue *queue, const size_t len);
+
 #endif /* SDL_dataqueue_h_ */
 
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