Day 35 complete.

handmade.h

@@ -143,6 +143,26 @@ typedef struct memory_arena {
     U64 Used;
 } memory_arena;
 
+static void InitializeArena(memory_arena *Arena, U64 Size, U8 *Base)
+{
+    Arena->Size = Size;
+    Arena->Base = Base;
+    Arena->Used = 0;
+}
+
+#define PUSH_STRUCT(Arena, type) (type *)PushSize_(Arena, sizeof(type))
+#define PUSH_ARRAY(Arena, Count, type) (type *)PushSize_(Arena, (Count)*sizeof(type))
+static void *PushSize_(memory_arena *Arena, U64 Size)
+{
+    void *Result;
+
+    ASSERT((Arena->Used + Size) <= Arena->Size);
+
+    Result = (void *)(Arena->Base + Arena->Used);
+    Arena->Used += Size;
+    return Result;
+}
+
 typedef struct world {
     tile_map *TileMap;
 } world;