From 4ebbaaa4625577ac112691445db8472b5e658b44 Mon Sep 17 00:00:00 2001
From: Judah Caruso <judah@tuta.io>
Date: Wed, 18 Feb 2026 23:31:03 -0700
Subject: [PATCH] region

---
 src/arena.c | 44 +++++++++++++++++++++++++++++++++++++-------
 src/main.c  | 24 +++++++++++++++++-------
 2 files changed, 54 insertions(+), 14 deletions(-)

diff --git a/src/arena.c b/src/arena.c
index 432a871..eb5bf0b 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -1,23 +1,27 @@
 #include <string.h>
 #include <stdlib.h>
+#include <assert.h>
 
-typedef enum { arena__alloc, arena__reset, arena__release } arena__action;
+typedef enum { arena__alloc, arena__reset, arena__save, arena__restore, arena__release } arena__action;
 
-typedef void* (^Arena)(arena__action, usize, usize, usize*, const char*, sreg);
+typedef void* (^Arena)(arena__action, usize, usize, void*, const char*, sreg);
 
-#define arena_new(A, T)  cast(T*, A(arena__alloc, sizeof(T), alignof(T), 0, __FILE__, __LINE__))
-#define arena_reset(A)   A(arena__reset, 0, 0, 0, __FILE__, __LINE__)
-#define arena_release(A) A(arena__release, 0, 0, 0, __FILE__, __LINE__)
+#define arena_new(A, T)      cast(T*, A(arena__alloc, sizeof(T), alignof(T), 0, __FILE__, __LINE__))
+#define arena_make(A, C, T)  cast(T*, A(arena__alloc, sizeof(T) * (C), alignof(T), 0, __FILE__, __LINE__))
+#define arena_reset(A)       A(arena__reset, 0, 0, 0, __FILE__, __LINE__)
+#define arena_release(A)     A(arena__release, 0, 0, 0, __FILE__, __LINE__)
+#define arena_save(A, SP)    A(arena__save, 0, 0, (SP), __FILE__, __LINE__)
+#define arena_restore(A, SP) A(arena__restore, 0, 0, (SP), __FILE__, __LINE__)
 
 // just a nice macro to make these easier to write
-#define func(a1, a2, a3, a4, a5, a6) ^void* (arena__action a1, usize a2, usize a3, usize* a4, const char* a5, sreg a6)
+#define func(a1, a2, a3, a4, a5, a6) ^void* (arena__action a1, usize a2, usize a3, void* a4, const char* a5, sreg a6)
 
 static Arena
 Static(u8* data, usize count) {
    memset(data, 0, count);
 
    capture usize offset = 0;
-   return closure(func(action, size, align, _1, _2, _3) {
+   return closure(func(action, size, align, savepoint, _2, _3) {
       switch (action) {
          default: {
          } break;
@@ -35,6 +39,16 @@ Static(u8* data, usize count) {
          case arena__reset: {
             offset = 0;
          } break;
+
+         case arena__save: {
+            assert(savepoint != NULL && "Static: savepoint was null");
+            *cast(usize*, savepoint) = offset;
+         } break;
+
+         case arena__restore: {
+            assert(savepoint != NULL && "Static: savepoint was null");
+            offset = *cast(usize*, savepoint);
+         } break;
       }
 
       return 0;
@@ -63,6 +77,8 @@ Logger(Arena arena) {
          case arena__alloc:   action_str = "alloc";   break;
          case arena__reset:   action_str = "reset";   break;
          case arena__release: action_str = "release"; break;
+         case arena__save:    action_str = "save";    break;
+         case arena__restore: action_str = "restore"; break;
       }
 
       printf("[ARENA] %s:%zd: %s (%zu, %zu)\n", file, line, action_str, size, align);
@@ -70,4 +86,18 @@ Logger(Arena arena) {
    });
 }
 
+static Arena
+Region(Arena arena) {
+   capture usize savepoint = 0;
+   arena_save(arena, &savepoint);
+
+   return closure(func(action, size, align, _, file, line) {
+      if (action == arena__reset || action == arena__restore) {
+         return arena(arena__restore, size, align, &savepoint, file, line);
+      }
+
+      return arena(action, size, align, &savepoint, file, line);
+   });
+}
+
 #undef func
diff --git a/src/main.c b/src/main.c
index 8b5d6f2..ffcb2b5 100644
--- a/src/main.c
+++ b/src/main.c
@@ -2,7 +2,6 @@
 #include "base.c"
 #include "arena.c"
 
-#define SOKOL_IMPL
 
 #ifdef PLATFORM_WINDOWS
    #define SOKOL_D3D11
@@ -14,6 +13,7 @@
    #error "unsupported platform"
 #endif
 
+#define SOKOL_IMPL
 #include "sokol/sokol_app.h"
 #include "sokol/sokol_gfx.h"
 #include "sokol/sokol_glue.h"
@@ -64,6 +64,16 @@ init(void) {
 
    sreg* a = arena_new(arena, sreg);
    sreg* b = arena_new(arena, sreg);
+
+   {
+      auto region = Region(arena);
+      scope_exit { arena_reset(region); };
+
+      arena_make(region, 10, sreg);
+      arena_make(region, 10, f32);
+      arena_make(region, 10, bool);
+   }
+
    sreg* c = arena_new(arena, sreg);
 
    *a = 1024;
@@ -96,14 +106,14 @@ frame(void) {
    });
 
    sdtx_origin(0, 0);
-	sdtx_canvas(sapp_widthf(), sapp_heightf());
+   sdtx_canvas(sapp_widthf(), sapp_heightf());
 
-	sdtx_font(3);
-	sdtx_pos(1, 1);
-	sdtx_color3b(0, 0xFF, 0);
-	sdtx_puts("press escape to quit");
+   sdtx_font(3);
+   sdtx_pos(1, 1);
+   sdtx_color3b(0, 0xFF, 0);
+   sdtx_puts("press escape to quit");
 
-	sdtx_draw();
+   sdtx_draw();
    sg_end_pass();
    sg_commit();
 }