Rework Arena into chain of MemoryBlock

src/arena.h

@@ -10,15 +10,20 @@ struct ArenaParams {
     ArenaFlags flags; // No flags defined yet
 };
 
-typedef struct Arena Arena;
-struct Arena {
-    Arena *current;
+typedef struct MemoryBlock MemoryBlock;
+struct MemoryBlock {
     U8 *base;
     U32 size;
-    U32 pos;          // start of next allocation
     U32 base_pos;     // absolute position of base relative to the first linked arena
+    U32 pos;          // start of next allocation
+    MemoryBlock *prev;
+};
+
+typedef struct Arena Arena;
+struct Arena {
+    MemoryBlock *current;
+    U32 requested_size;
     ArenaFlags flags;
-    Arena *prev;
     S32 checkpoint_level;
 };
 
@@ -28,16 +33,13 @@ struct ArenaCheckPoint {
     U32 absolute_pos;
 };
 
-StaticAssert(sizeof(Arena) <= 64);
-#define ARENA_HEADER_SZ 64u
+StaticAssert(sizeof(MemoryBlock) <= 64);
+#define MemoryBlock_Header_Size 64u
 
 
-static INLINE U32 arena_available(const Arena *arena)
-{
-    return arena->size - arena->pos;
-}
 
-Arena *arena_alloc(const ArenaParams *params);
+void arena_init(Arena *arena, const ArenaParams *params);
+
 void arena_free(Arena *arena);
 void *arena_push(Arena *arena, U32 size, U32 align);
 
@@ -48,3 +50,15 @@ ArenaCheckPoint arena_temp_begin(Arena *arena);
 void arena_temp_end(ArenaCheckPoint *checkpoint);
 void arena_pop_to(Arena *arena, U32 abs_pos);
 void arena_reset(Arena *arena);
+MemoryBlock *memoryblock_allocate(size_t size);
+
+static INLINE U32 memoryblock_available(const MemoryBlock *block)
+{
+    return block->size - block->pos;
+}
+
+static INLINE U32 arena_used(const Arena *arena)
+{
+    const MemoryBlock *block = arena->current;
+    return block->base_pos + block->pos;
+}