3 files changed, 27 insertions, 14 deletions
diff --git a/include/mruby.h b/include/mruby.h
index 9fe70e5b8..73c38cf1d 100644
--- a/include/mruby.h
+++ b/include/mruby.h
@@ -61,16 +61,8 @@ typedef struct {
   struct REnv *env;
 } mrb_callinfo;
 
-enum gc_state {
-  GC_STATE_NONE = 0,
-  GC_STATE_MARK,
-  GC_STATE_SWEEP
-};
-
-typedef struct mrb_state {
-  void *jmp;
-
-  mrb_allocf allocf;
+struct mrb_context {
+  struct mrb_context *prev;
 
   mrb_value *stack;
   mrb_value *stbase, *stend;
@@ -82,10 +74,24 @@ typedef struct mrb_state {
   int rsize;
   struct RProc **ensure;
   int esize;
+};
+
+enum gc_state {
+  GC_STATE_NONE = 0,
+  GC_STATE_MARK,
+  GC_STATE_SWEEP
+};
+
+typedef struct mrb_state {
+  void *jmp;
+
+  mrb_allocf allocf;
+
+  struct mrb_context *c;
+  struct mrb_context *root_c;
 
   struct RObject *exc;
   struct iv_tbl *globals;
-
   struct mrb_irep **irep;
   size_t irep_len, irep_capa;
 
@@ -140,7 +146,6 @@ typedef struct mrb_state {
   struct RClass *eStandardError_class;
 
   void *ud; /* auxiliary data */
-
 } mrb_state;
 
 typedef mrb_value (*mrb_func_t)(mrb_state *mrb, mrb_value);
diff --git a/include/mruby/gc.h b/include/mruby/gc.h
index 2f7dc73cf..7afa24b48 100644
--- a/include/mruby/gc.h
+++ b/include/mruby/gc.h
@@ -12,5 +12,6 @@
 
 typedef void (each_object_callback)(mrb_state *mrb, struct RBasic* obj, void *data);
 void mrb_objspace_each_objects(mrb_state *mrb, each_object_callback* callback, void *data);
+void mrb_free_context(mrb_state *mrb, struct mrb_context *c);
 
 #endif  /* MRUBY_GC_H */
diff --git a/include/mruby/value.h b/include/mruby/value.h
index 0ce59e06a..fa2a68ac8 100644
--- a/include/mruby/value.h
+++ b/include/mruby/value.h
@@ -34,7 +34,8 @@ enum mrb_vtype {
   MRB_TT_FILE,        /*  19 */
   MRB_TT_ENV,         /*  20 */
   MRB_TT_DATA,        /*  21 */
-  MRB_TT_MAXDEFINE    /*  22 */
+  MRB_TT_FIBER,       /*  22 */
+  MRB_TT_MAXDEFINE    /*  23 */
 };
 
 typedef struct mrb_value {
@@ -92,7 +93,8 @@ enum mrb_vtype {
   MRB_TT_FILE,        /*  20 */
   MRB_TT_ENV,         /*  21 */
   MRB_TT_DATA,        /*  22 */
-  MRB_TT_MAXDEFINE    /*  23 */
+  MRB_TT_FIBER,       /*  23 */
+  MRB_TT_MAXDEFINE    /*  24 */
 };
 
 #ifdef MRB_ENDIAN_BIG
@@ -202,6 +204,11 @@ struct RObject {
 #define mrb_immediate_p(x) (mrb_type(x) <= MRB_TT_VOIDP)
 #define mrb_special_const_p(x) mrb_immediate_p(x)
 
+struct RFiber {
+  MRB_OBJECT_HEADER;
+  struct mrb_context *cxt;
+};
+
 static inline mrb_value
 mrb_fixnum_value(mrb_int i)
 {