Reorganisation of the source tree

[ghc-hetmet.git] / rts / gmp / mpn / generic / scan1.c

diff --git a/rts/gmp/mpn/generic/scan1.c b/rts/gmp/mpn/generic/scan1.c
new file mode 100644 (file)
index 0000000..98e2e0d
--- /dev/null
+++ b/rts/gmp/mpn/generic/scan1.c
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+/* mpn_scan1 -- Scan from a given bit position for the next set bit.
+
+Copyright (C) 1994, 1996 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 2.1 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; see the file COPYING.LIB.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+MA 02111-1307, USA. */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+#include "longlong.h"
+
+/* Design issues:
+   1. What if starting_bit is not within U?  Caller's problem?
+   2. Bit index should be 'unsigned'?
+
+   Argument constraints:
+   1. U must sooner ot later have a limb != 0.
+ */
+
+unsigned long int
+#if __STDC__
+mpn_scan1 (register mp_srcptr up,
+          register unsigned long int starting_bit)
+#else
+mpn_scan1 (up, starting_bit)
+     register mp_srcptr up;
+     register unsigned long int starting_bit;
+#endif
+{
+  mp_size_t starting_word;
+  mp_limb_t alimb;
+  int cnt;
+  mp_srcptr p;
+
+  /* Start at the word implied by STARTING_BIT.  */
+  starting_word = starting_bit / BITS_PER_MP_LIMB;
+  p = up + starting_word;
+  alimb = *p++;
+
+  /* Mask off any bits before STARTING_BIT in the first limb.  */
+  alimb &= - (mp_limb_t) 1 << (starting_bit % BITS_PER_MP_LIMB);
+
+  while (alimb == 0)
+    alimb = *p++;
+
+  count_leading_zeros (cnt, alimb & -alimb);
+  return (p - up) * BITS_PER_MP_LIMB - 1 - cnt;
+}