Imported gcc-4.4.3

[msp430-gcc.git] / gmp / mpz / divis_2exp.c

diff --git a/gmp/mpz/divis_2exp.c b/gmp/mpz/divis_2exp.c
new file mode 100644 (file)
index 0000000..5e07b4a
--- /dev/null
+++ b/gmp/mpz/divis_2exp.c
@@ -0,0 +1,49 @@
+/* mpz_divisible_2exp_p -- mpz by 2^n divisibility test
+
+Copyright 2001, 2002 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP Library is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 3 of the License, or (at your
+option) any later version.
+
+The GNU MP Library is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
+License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+
+
+int
+mpz_divisible_2exp_p (mpz_srcptr a, unsigned long d)
+{
+  unsigned long  i, dlimbs, dbits;
+  mp_ptr         ap;
+  mp_limb_t      dmask;
+  mp_size_t      asize;
+
+  asize = ABSIZ(a);
+  dlimbs = d / GMP_NUMB_BITS;
+
+  /* if d covers the whole of a, then only a==0 is divisible */
+  if (asize <= dlimbs)
+    return asize == 0;
+
+  /* whole limbs must be zero */
+  ap = PTR(a);
+  for (i = 0; i < dlimbs; i++)
+    if (ap[i] != 0)
+      return 0;
+
+  /* left over bits must be zero */
+  dbits = d % GMP_NUMB_BITS;
+  dmask = (CNST_LIMB(1) << dbits) - 1;
+  return (ap[dlimbs] & dmask) == 0;
+}