From 85a766a24250a4a757e096843cc79e3370cb3ca1 Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Thu, 20 Feb 2014 17:41:59 +0900
Subject: [PATCH] adjust stack pointer to the next to the initial position
 after calling function

---
 src/cont.c | 18 +++++++++---------
 src/vm.c   | 11 ++++++-----
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/src/cont.c b/src/cont.c
index 6e7dc00b..f89c9728 100644
--- a/src/cont.c
+++ b/src/cont.c
@@ -181,13 +181,13 @@ pic_values(pic_state *pic, size_t c, ...)
   va_start(ap, c);
 
   for (i = 0; i < c; ++i) {
-    *pic->sp++ = va_arg(ap, pic_value);
+    pic->sp[i] = va_arg(ap, pic_value);
   }
   pic->ci->retc = c;
 
   va_end(ap);
 
-  return c == 0 ? pic_none_value() : pic->sp[-c];
+  return c == 0 ? pic_none_value() : pic->sp[0];
 }
 
 pic_value
@@ -196,26 +196,26 @@ pic_values_by_array(pic_state *pic, size_t argc, pic_value *argv)
   size_t i;
 
   for (i = 0; i < argc; ++i) {
-    *pic->sp++ = argv[i];
+    pic->sp[i] = argv[i];
   }
   pic->ci->retc = argc;
 
-  return argc == 0 ? pic_none_value() : pic->sp[-argc];
+  return argc == 0 ? pic_none_value() : pic->sp[0];
 }
 
 pic_value
 pic_values_by_list(pic_state *pic, pic_value list)
 {
   pic_value v;
-  size_t c;
+  size_t i;
 
-  c = pic_length(pic, list);
+  i = 0;
   pic_for_each (v, list) {
-    *pic->sp++ = v;
+    pic->sp[i++] = v;
   }
-  pic->ci->retc = c;
+  pic->ci->retc = i;
 
-  return pic_nil_p(list) ? pic_none_value() : pic->sp[-c];
+  return pic_nil_p(list) ? pic_none_value() : pic->sp[0];
 }
 
 size_t
diff --git a/src/vm.c b/src/vm.c
index 48823f23..b97061a3 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -572,10 +572,8 @@ pic_apply(pic_state *pic, struct pic_proc *proc, pic_value argv)
       if (pic_proc_cfunc_p(x)) {
 
         /* invoke! */
-	v = proc->u.cfunc(pic);
-        if (ci->retc == 1 && pic->sp == ci->fp + c.u.i) {
-          PUSH(v);
-        }
+	pic->sp[0] = proc->u.cfunc(pic);
+        pic->sp += ci->retc;
 
         pic_gc_arena_restore(pic, ai);
         goto L_RET;
@@ -656,11 +654,14 @@ pic_apply(pic_state *pic, struct pic_proc *proc, pic_value argv)
     L_RET:
       retc = pic->ci->retc;
       retv = pic->sp - retc;
+      if (retc == 0) {
+        pic->ci->fp[0] = retv[0]; /* copy at least once */
+      }
       for (i = 0; i < retc; ++i) {
         pic->ci->fp[i] = retv[i];
       }
       ci = POPCI();
-      pic->sp = ci->fp + retc;
+      pic->sp = ci->fp + 1;     /* advance only one! */
       pic->ip = ci->ip;
 
       NEXT;