fix ROTATE-BYTE on 64-bit words using constant negative rotation

[sbcl.git] / contrib / sb-rotate-byte / x86-64-vm.lisp

diff --git a/contrib/sb-rotate-byte/x86-64-vm.lisp b/contrib/sb-rotate-byte/x86-64-vm.lisp
index d45b596..a311933 100644 (file)
--- a/contrib/sb-rotate-byte/x86-64-vm.lisp
+++ b/contrib/sb-rotate-byte/x86-64-vm.lisp
@@ -59,7 +59,7 @@
     (move result integer)
     (if (> count 0)
         (inst rol result count)
-        (inst ror result count))))
+        (inst ror result (- count)))))
 
 (define-vop (%64bit-rotate-byte)
   (:policy :fast-safe)