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fix bug in ash opcode

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* libguile/vm-i-scheme.c (ash): Fix embarrassing bug in (ash 1 32).
* test-suite/tests/bit-operations.test ("bitshifts on word boundaries"):
  Add tests.
This commit is contained in:
Andy Wingo 2010-03-31 22:29:29 +02:00
parent e275b8a220
commit 8ecd1943ef
2 changed files with 21 additions and 4 deletions
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19
libguile/vm-i-scheme.c
View file

@ -287,10 +287,23 @@ VM_DEFINE_FUNCTION (157, ash, "ash", 2)
if (SCM_I_INUMP (x) && SCM_I_INUMP (y))
{
if (SCM_I_INUM (y) < 0)
/* Right shift, will be a fixnum. */
RETURN (SCM_I_MAKINUM (SCM_I_INUM (x) >> -SCM_I_INUM (y)));
else if ((SCM_I_INUM (x) << SCM_I_INUM (y)) >> SCM_I_INUM (y)
== SCM_I_INUM (x))
RETURN (SCM_I_MAKINUM (SCM_I_INUM (x) << SCM_I_INUM (y)));
else
/* Left shift. See comments in scm_ash. */
{
long nn, bits_to_shift;
nn = SCM_I_INUM (x);
bits_to_shift = SCM_I_INUM (y);
if (bits_to_shift < SCM_I_FIXNUM_BIT-1
&& ((unsigned long)
(SCM_SRS (nn, (SCM_I_FIXNUM_BIT-1 - bits_to_shift)) + 1)
<= 1))
RETURN (SCM_I_MAKINUM (nn << bits_to_shift));
/* fall through */
}
/* fall through */
}
SYNC_REGISTER ();

6
test-suite/tests/bit-operations.test
View file

@ -1,5 +1,5 @@
;;;; bit-operations.test --- bitwise operations on numbers -*- scheme -*-
;;;; Copyright (C) 2000, 2001, 2003, 2006, 2009 Free Software Foundation, Inc.
;;;; Copyright (C) 2000, 2001, 2003, 2006, 2009, 2010 Free Software Foundation, Inc.
;;;;
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
@ -362,3 +362,7 @@
(+ fixnum-bit fixnum-bit 1) (- (ash 1 (+ fixnum-bit 1)) 1))
(list (- fixnum-min 1) (+ fixnum-bit 1)
(+ fixnum-bit fixnum-bit 2) (- (ash 1 (+ fixnum-bit 1)) 1))))))
(with-test-prefix "bitshifts on word boundaries"
(pass-if (= (ash 1 32) 4294967296))
(pass-if (= (ash 1 64) 18446744073709551616)))