[gcc] GCC 4.5.0=>4.5.1

gcc/mpfr/eq.c

-/* mpfr_eq -- Compare two floats up to a specified bit #.
-
-Copyright 1999, 2001, 2003, 2004, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
-Contributed by the Arenaire and Cacao projects, INRIA.
-
-This file is part of the GNU MPFR Library.
-
-The GNU MPFR 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 MPFR 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 MPFR Library; see the file COPYING.LIB.  If not, write to
-the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
-MA 02110-1301, USA. */
-
-
-#include "mpfr-impl.h"
-
-/* return non-zero if the first n_bits bits of u, v are equal,
-   0 otherwise */
-int
-mpfr_eq (mpfr_srcptr u, mpfr_srcptr v, unsigned long int n_bits)
-{
-  mp_srcptr up, vp;
-  mp_size_t usize, vsize, size, i;
-  mp_exp_t uexp, vexp;
-  int k;
-
-  if (MPFR_ARE_SINGULAR(u, v))
-    {
-      if (MPFR_IS_NAN(u) || MPFR_IS_NAN(v))
-        return 0; /* non equal */
-      else if (MPFR_IS_INF(u) && MPFR_IS_INF(v))
-        return (MPFR_SIGN(u) == MPFR_SIGN(v));
-      else if (MPFR_IS_ZERO(u) && MPFR_IS_ZERO(v))
-        return 1;
-      else
-        return 0;
-    }
-
-  /* 1. Are the signs different?  */
-  if (MPFR_SIGN(u) != MPFR_SIGN(v))
-    return 0;
-
-  uexp = MPFR_GET_EXP (u);
-  vexp = MPFR_GET_EXP (v);
-
-  /* 2. Are the exponents different?  */
-  if (uexp != vexp)
-    return 0; /* no bit agree */
-
-  usize = (MPFR_PREC(u) - 1) / BITS_PER_MP_LIMB + 1;
-  vsize = (MPFR_PREC(v) - 1) / BITS_PER_MP_LIMB + 1;
-
-  if (vsize > usize) /* exchange u and v */
-    {
-      up = MPFR_MANT(v);
-      vp = MPFR_MANT(u);
-      size = vsize;
-      vsize = usize;
-      usize = size;
-    }
-  else
-    {
-      up = MPFR_MANT(u);
-      vp = MPFR_MANT(v);
-    }
-
-  /* now usize >= vsize */
-  MPFR_ASSERTD(usize >= vsize);
-
-  if (usize > vsize)
-    {
-      if ((unsigned long) vsize * BITS_PER_MP_LIMB < n_bits)
-        {
-          /* check if low min(PREC(u), n_bits) - (vsize * BITS_PER_MP_LIMB)
-             bits from u are non-zero */
-          unsigned long remains = n_bits - (vsize * BITS_PER_MP_LIMB);
-          k = usize - vsize - 1;
-          while (k >= 0 && remains >= BITS_PER_MP_LIMB && !up[k])
-            {
-              k--;
-              remains -= BITS_PER_MP_LIMB;
-            }
-          /* now either k < 0: all low bits from u are zero
-                 or remains < BITS_PER_MP_LIMB: check high bits from up[k]
-                 or up[k] <> 0: different */
-          if (k >= 0 && (((remains < BITS_PER_MP_LIMB) &&
-                          (up[k] >> (BITS_PER_MP_LIMB - remains))) ||
-                         (remains >= BITS_PER_MP_LIMB && up[k])))
-            return 0;           /* surely too different */
-        }
-      size = vsize;
-    }
-  else
-    {
-      size = usize;
-    }
-
-  /* now size = min (usize, vsize) */
-
-  /* If size is too large wrt n_bits, reduce it to look only at the
-     high n_bits bits.
-     Otherwise, if n_bits > size * BITS_PER_MP_LIMB, reduce n_bits to
-     size * BITS_PER_MP_LIMB, since the extra low bits of one of the
-     operands have already been check above. */
-  if ((unsigned long) size > 1 + (n_bits - 1) / BITS_PER_MP_LIMB)
-    size = 1 + (n_bits - 1) / BITS_PER_MP_LIMB;
-  else if (n_bits > (unsigned long) size * BITS_PER_MP_LIMB)
-    n_bits = size * BITS_PER_MP_LIMB;
-
-  up += usize - size;
-  vp += vsize - size;
-
-  for (i = size - 1; i > 0 && n_bits >= BITS_PER_MP_LIMB; i--)
-    {
-      if (up[i] != vp[i])
-        return 0;
-      n_bits -= BITS_PER_MP_LIMB;
-    }
-
-  /* now either i=0 or n_bits<BITS_PER_MP_LIMB */
-
-  /* since n_bits <= size * BITS_PER_MP_LIMB before the above for-loop,
-     we have the invariant n_bits <= (i+1) * BITS_PER_MP_LIMB, thus
-     we always have n_bits <= BITS_PER_MP_LIMB here */
-  MPFR_ASSERTD(n_bits <= BITS_PER_MP_LIMB);
-
-  if (n_bits & (BITS_PER_MP_LIMB - 1))
-    return (up[i] >> (BITS_PER_MP_LIMB - (n_bits & (BITS_PER_MP_LIMB - 1))) ==
-            vp[i] >> (BITS_PER_MP_LIMB - (n_bits & (BITS_PER_MP_LIMB - 1))));
-  else
-    return (up[i] == vp[i]);
-}