-extern scm_t_bits scm_tc16_heap_frame;
-
-#define SCM_HEAP_FRAME_P(x) SCM_SMOB_PREDICATE (scm_tc16_heap_frame, x)
-#define SCM_HEAP_FRAME_DATA(f) ((SCM *) SCM_SMOB_DATA (f))
-#define SCM_HEAP_FRAME_SELF(f) (SCM_HEAP_FRAME_DATA (f) + 0)
-#define SCM_HEAP_FRAME_POINTER(f) (SCM_HEAP_FRAME_DATA (f) + 2)
-#define SCM_VALIDATE_HEAP_FRAME(p,x) SCM_MAKE_VALIDATE (p, x, HEAP_FRAME_P)
-
-extern SCM scm_heap_frame_p (SCM obj);
-extern SCM scm_frame_program (SCM frame);
-extern SCM scm_frame_local_ref (SCM frame, SCM index);
-extern SCM scm_frame_local_set_x (SCM frame, SCM index, SCM val);
-extern SCM scm_frame_return_address (SCM frame);
-extern SCM scm_frame_mv_return_address (SCM frame);
-extern SCM scm_frame_dynamic_link (SCM frame);
-extern SCM scm_frame_external_link (SCM frame);
+extern scm_t_bits scm_tc16_vm_frame;
+
+struct scm_vm_frame
+{
+ SCM stack_holder;
+ SCM *fp;
+ SCM *sp;
+ scm_byte_t *ip;
+ scm_t_ptrdiff offset;
+};
+
+#define SCM_VM_FRAME_P(x) SCM_SMOB_PREDICATE (scm_tc16_vm_frame, x)
+#define SCM_VM_FRAME_DATA(x) ((struct scm_vm_frame*)SCM_SMOB_DATA (x))
+#define SCM_VM_FRAME_STACK_HOLDER(f) SCM_VM_FRAME_DATA(f)->stack_holder
+#define SCM_VM_FRAME_FP(f) SCM_VM_FRAME_DATA(f)->fp
+#define SCM_VM_FRAME_SP(f) SCM_VM_FRAME_DATA(f)->sp
+#define SCM_VM_FRAME_IP(f) SCM_VM_FRAME_DATA(f)->ip
+#define SCM_VM_FRAME_OFFSET(f) SCM_VM_FRAME_DATA(f)->offset
+#define SCM_VALIDATE_VM_FRAME(p,x) SCM_MAKE_VALIDATE (p, x, VM_FRAME_P)
+
+/* FIXME rename scm_byte_t */
+extern SCM scm_c_make_vm_frame (SCM stack_holder, SCM *fp, SCM *sp,
+ scm_byte_t *ip, scm_t_ptrdiff offset);
+extern SCM scm_vm_frame_p (SCM obj);
+extern SCM scm_vm_frame_program (SCM frame);
+extern SCM scm_vm_frame_arguments (SCM frame);
+extern SCM scm_vm_frame_source (SCM frame);
+extern SCM scm_vm_frame_local_ref (SCM frame, SCM index);
+extern SCM scm_vm_frame_local_set_x (SCM frame, SCM index, SCM val);
+extern SCM scm_vm_frame_return_address (SCM frame);
+extern SCM scm_vm_frame_mv_return_address (SCM frame);
+extern SCM scm_vm_frame_dynamic_link (SCM frame);
+extern SCM scm_vm_frame_external_link (SCM frame);
+extern SCM scm_vm_frame_stack (SCM frame);
+
+extern SCM scm_c_vm_frame_prev (SCM frame);