4 files changed, 48 insertions, 1 deletions
diff --git a/uscript/uscript.c b/uscript/uscript.c
index a7e3ca1..0e6fc4b 100644
--- a/uscript/uscript.c
+++ b/uscript/uscript.c
@@ -36,12 +36,46 @@ void core_len(int argc)
         }
 }
 
+void core_range_next(int argc)
+{
+        (void)argc;
+
+        struct us_cfunc *cfunc = get_cfunc(vm_get(-1));
+        double min = get_num(cfunc_get_upval(cfunc, 0));
+        double max = get_num(cfunc_get_upval(cfunc, 1));
+
+        if (min == max) {
+                vm_push(create_zilch());
+                return;
+        }
+
+        vm_push(create_num(min));
+
+        int inc = max > min ? 1 : -1;
+        cfunc_set_upval(cfunc, 0, create_num(min + inc));
+}
+
+void core_range(int argc)
+{
+        if (vm_get(1).type != VAL_NUM || vm_get(2).type != VAL_NUM)
+                log_fatal(1, "core:range expected two numbers");
+
+        struct us_str *str = copy_str("rangenext", -1);
+        struct us_cfunc *cfunc = create_cfunc(str, core_range_next, 0);
+
+        for (int i = 0; i < argc; i++)
+                cfunc_add_upval(cfunc, vm_get(i));
+
+        vm_push(wrap_cfunc(cfunc));
+}
+
 void us_init(void)
 {
         init_vm();
 
         us_set_cfunc("core:len", core_len, 1);
         us_set_cfunc("core:log", core_print, 1);
+        us_set_cfunc("core:range", core_range, 2);
 }
 
 void us_deinit(void)
diff --git a/uscript/val.c b/uscript/val.c
index 357facc..76f1376 100644
--- a/uscript/val.c
+++ b/uscript/val.c
@@ -74,6 +74,7 @@ struct us_cfunc *create_cfunc(struct us_str *name, us_cfunc_sig func, int argc)
         cfunc->name = name;
         cfunc->c = func;
         cfunc->argc = argc;
+        cfunc->upvals = da_create(struct us_val, 0);
         init_obj(wrap_cfunc(cfunc), &cfunc->header);
         return cfunc;
 }
@@ -116,7 +117,12 @@ void free_val(struct us_val v)
                 mem_free(func);
                 break;
         }
-        case VAL_CFUNC:
+        case VAL_CFUNC: {
+                struct us_cfunc *cfunc = get_cfunc(v);
+                da_free(cfunc->upvals);
+                mem_free(cfunc);
+                break;
+        }
         case VAL_UPVAL:
                 mem_free(get_obj(v));
                 break;
diff --git a/uscript/val.h b/uscript/val.h
index 5140fc2..8ea91dd 100644
--- a/uscript/val.h
+++ b/uscript/val.h
@@ -28,6 +28,10 @@
 
 #define proto_add_byte(func, op) da_append(u8, &(func)->bytecode, op)
 
+#define cfunc_add_upval(c, v) da_append(struct us_val, &c->upvals, v)
+#define cfunc_set_upval(c, i, v) (c->upvals[i] = (v))
+#define cfunc_get_upval(c, i) (c->upvals[i])
+
 enum val_type {
         VAL_NUM,
         VAL_BOOL,
@@ -90,6 +94,7 @@ struct us_cfunc {
         struct us_obj header;
         us_cfunc_sig c;
         const struct us_str *name;
+        struct us_val *upvals;
         int argc;
 };
 
diff --git a/uscript/vm.h b/uscript/vm.h
index d3487b1..9ab1407 100644
--- a/uscript/vm.h
+++ b/uscript/vm.h
@@ -11,6 +11,8 @@
 #define vm_peek()  (vm.stacktop[-1])
 #define vm_push(v) (*vm.stacktop++ = (v))
 
+#define vm_get(i)  (vm.cf->stackbot[i])
+
 #define set_global(idx, v) (vm.gstack[idx].val = (v))
 #define get_global(idx)    (vm.gstack[idx].val)