buflib: Add CONFIG_BUFLIB_BACKEND for selecting a buflib backend

Defaults to the normal "mempool" backend, which is currently the
only implementation.

Change-Id: I56d034a6e0f5edc90c39526d1551945eec6ca336

firmware/include/buflib.h

@@ -0,0 +1,30 @@
+/**************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2023 Aidan MacDonald
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#ifndef _BUFLIB_H_
+#define _BUFLIB_H_
+
+#include "config.h"
+
+#if CONFIG_BUFLIB_BACKEND == BUFLIB_BACKEND_MEMPOOL
+#include "buflib_mempool.h"
+#endif
+
+#endif /* _BUFLIB_H_ */

firmware/include/buflib_mempool.h

@@ -26,6 +26,10 @@
 #ifndef _BUFLIB_MEMPOOL_H_
 #define _BUFLIB_MEMPOOL_H_
 
+#ifndef _BUFLIB_H_
+# error "include buflib.h instead"
+#endif
+
 #include <stdint.h>
 #include <stdbool.h>
 #include <string.h>

firmware/include/chunk_alloc.h

@@ -24,7 +24,7 @@
 #include <stdbool.h>
 #include <string.h>
 #include "config.h"
-#include "buflib_mempool.h"
+#include "buflib.h"
 
 #define CHUNK_ALLOC_INVALID ((size_t)-1)
 

firmware/include/core_alloc.h

@@ -4,7 +4,7 @@
 #include <string.h>
 #include <stdbool.h>
 #include "config.h"
-#include "buflib_mempool.h"
+#include "buflib.h"
 #include "chunk_alloc.h"
 
 /* All functions below are wrappers for functions in buflib.h, except