From ee985a31cdf8579bd178e0aaa67d308cb4501363 Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Sun, 13 Oct 2013 17:02:29 +0900
Subject: [PATCH] add GC arena

---
 include/picrin.h |  3 +++
 src/gc.c         | 22 ++++++++++++++++++++++
 src/state.c      |  4 ++++
 3 files changed, 29 insertions(+)

diff --git a/include/picrin.h b/include/picrin.h
index 6eafba52..76241b67 100644
--- a/include/picrin.h
+++ b/include/picrin.h
@@ -11,6 +11,7 @@ struct pic_env {
   struct pic_env *parent;
 };
 
+#define PIC_ARENA_SIZE 1024
 #define PIC_HEAP_SIZE 1024
 
 typedef struct {
@@ -20,6 +21,8 @@ typedef struct {
   struct pic_env *global_env;
 
   struct heap_page *heap;
+  struct pic_object *arena[PIC_ARENA_SIZE];
+  int arena_idx;
 } pic_state;
 
 void *pic_alloc(pic_state *, size_t);
diff --git a/src/gc.c b/src/gc.c
index 1c5f4ded..c51a2e8c 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -104,5 +104,27 @@ pic_obj_alloc(pic_state *pic, size_t size, enum pic_tt tt)
   obj = (struct pic_object *)malloc(size);
   obj->tt = tt;
 
+  pic_gc_protect(pic, obj);
   return obj;
 }
+
+void
+pic_gc_protect(pic_state *pic, struct pic_object *obj)
+{
+  if (pic->arena_idx >= PIC_ARENA_SIZE) {
+    pic_raise(pic, "arena overflow");
+  }
+  pic->arena[pic->arena_idx++] = obj;
+}
+
+int
+pic_gc_arena_preserve(pic_state *pic)
+{
+  return pic->arena_idx;
+}
+
+void
+pic_gc_arena_restore(pic_state *pic, int state)
+{
+  pic->arena_idx = state;
+}
diff --git a/src/state.c b/src/state.c
index 812c0299..17ad6368 100644
--- a/src/state.c
+++ b/src/state.c
@@ -30,6 +30,10 @@ pic_open()
   pic->heap = (struct heap_page *)malloc(sizeof(struct heap_page));
   init_heap_page(pic->heap);
 
+  /* GC arena */
+  pic->arena = (struct pic_object *)calloc(PIC_ARENA_SIZE, sizeof(struct pic_object *));
+  pic->arena_idx = 0;
+
   pic->global_env = pic_new_empty_env();
 
   return pic;