Restructure the library layers

src/os/allocators/arena/mem_arena_allocator.h

@@ -0,0 +1,43 @@
+// vim:fileencoding=utf-8:foldmethod=marker
+
+#ifndef MEM_ARENA_ALLOCATOR_H
+#define MEM_ARENA_ALLOCATOR_H
+
+#include "../../mem/mem_os.h"
+#include "../../../common/aliases/aliases.h"
+#include "../../../common/platform/platform.h"
+#include "../../../base/mem/allocator/mem_allocator.h"
+
+#ifdef WAPP_PLATFORM_CPP
+BEGIN_C_LINKAGE
+#endif // !WAPP_PLATFORM_CPP
+
+#define wapp_mem_arena_allocator_init(base_capacity)                           \
+  (wapp_mem_arena_allocator_init_custom(base_capacity, WAPP_MEM_ALLOC_RESERVE, false))
+#define wapp_mem_arena_allocator_init_commit(base_capacity)                    \
+  (wapp_mem_arena_allocator_init_custom(base_capacity, WAPP_MEM_ALLOC_RESERVE | WAPP_MEM_ALLOC_COMMIT, false))
+#define wapp_mem_arena_allocator_init_zero(base_capacity)                      \
+  (wapp_mem_arena_allocator_init_custom(base_capacity, WAPP_MEM_ALLOC_RESERVE, true))
+#define wapp_mem_arena_allocator_init_commit_and_zero(base_capacity)           \
+  (wapp_mem_arena_allocator_init_custom(base_capacity, WAPP_MEM_ALLOC_RESERVE | WAPP_MEM_ALLOC_COMMIT, true))
+
+/**
+ * Wraps an Arena in an Allocator object. It attempts to initialise the Arena
+ * and, if successful, defines the operations supported by it to be used by the
+ * Allocator.
+ *
+ * An Arena allocator only supports normal allocation and aligned allocation.
+ * Reallocation, aligned reallocation and freeing aren't implemented.
+ *
+ * The `wapp_mem_arena_allocator_init_custom` provides the most control over how
+ * the Arena is initialised. Wrapper macros are provided for easier use.
+ */
+Allocator wapp_mem_arena_allocator_init_custom(u64 base_capacity, MemAllocFlags flags, b8 zero_buffer);
+void wapp_mem_arena_allocator_clear(Allocator *allocator);
+void wapp_mem_arena_allocator_destroy(Allocator *allocator);
+
+#ifdef WAPP_PLATFORM_CPP
+END_C_LINKAGE
+#endif // !WAPP_PLATFORM_CPP
+
+#endif // !MEM_ARENA_ALLOCATOR_H