add c and jai

c/base/base_arena.h

@@ -0,0 +1,44 @@
+#pragma once
+// base_arena.h - Linear arena allocator
+// Simplified from raddebugger's virtual-memory-backed arena to a malloc-based one.
+// Suitable for per-frame scratch allocations and persistent state.
+
+#include "base/base_core.h"
+
+////////////////////////////////
+// Arena type
+
+typedef struct Arena {
+    U8  *base;
+    U64  pos;
+    U64  cap;
+} Arena;
+
+// Temporary scope (save/restore position)
+typedef struct Temp {
+    Arena *arena;
+    U64    pos;
+} Temp;
+
+////////////////////////////////
+// Arena functions
+
+Arena *arena_alloc(U64 cap);
+void   arena_release(Arena *arena);
+void  *arena_push(Arena *arena, U64 size);
+void  *arena_push_no_zero(Arena *arena, U64 size);
+U64    arena_pos(Arena *arena);
+void   arena_pop_to(Arena *arena, U64 pos);
+void   arena_clear(Arena *arena);
+
+////////////////////////////////
+// Temporary scope helpers
+
+static inline Temp temp_begin(Arena *arena) { Temp t = {arena, arena->pos}; return t; }
+static inline void temp_end(Temp temp)      { arena_pop_to(temp.arena, temp.pos); }
+
+////////////////////////////////
+// Push helper macros
+
+#define push_array(arena, T, count)         ((T *)arena_push((arena), sizeof(T) * (count)))
+#define push_array_no_zero(arena, T, count) ((T *)arena_push_no_zero((arena), sizeof(T) * (count)))