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+/* mpfr_get_f -- convert a MPFR number to a GNU MPF number
+
+Copyright 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc.
+Contributed by the AriC and Caramel 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 3 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.LESSER. If not, see
+http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
+51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
+
+#include "mpfr-impl.h"
+
+/* Since MPFR-3.0, return the usual inexact value.
+ The erange flag is set if an error occurred in the conversion
+ (y is NaN, +Inf, or -Inf that have no equivalent in mpf)
+*/
+int
+mpfr_get_f (mpf_ptr x, mpfr_srcptr y, mpfr_rnd_t rnd_mode)
+{
+ int inex;
+ mp_size_t sx, sy;
+ mpfr_prec_t precx, precy;
+ mp_limb_t *xp;
+ int sh;
+
+ if (MPFR_UNLIKELY(MPFR_IS_SINGULAR(y)))
+ {
+ if (MPFR_IS_ZERO(y))
+ {
+ mpf_set_ui (x, 0);
+ return 0;
+ }
+ else if (MPFR_IS_NAN (y))
+ {
+ MPFR_SET_ERANGE ();
+ return 0;
+ }
+ else /* y is plus infinity (resp. minus infinity), set x to the maximum
+ value (resp. the minimum value) in precision PREC(x) */
+ {
+ int i;
+ mp_limb_t *xp;
+
+ MPFR_SET_ERANGE ();
+
+ /* To this day, [mp_exp_t] and mp_size_t are #defined as the same
+ type */
+ EXP (x) = MP_SIZE_T_MAX;
+
+ sx = PREC (x);
+ SIZ (x) = sx;
+ xp = PTR (x);
+ for (i = 0; i < sx; i++)
+ xp[i] = MP_LIMB_T_MAX;
+
+ if (MPFR_IS_POS (y))
+ return -1;
+ else
+ {
+ mpf_neg (x, x);
+ return +1;
+ }
+ }
+ }
+
+ sx = PREC(x); /* number of limbs of the mantissa of x */
+
+ precy = MPFR_PREC(y);
+ precx = (mpfr_prec_t) sx * GMP_NUMB_BITS;
+ sy = MPFR_LIMB_SIZE (y);
+
+ xp = PTR (x);
+
+ /* since mpf numbers are represented in base 2^GMP_NUMB_BITS,
+ we loose -EXP(y) % GMP_NUMB_BITS bits in the most significant limb */
+ sh = MPFR_GET_EXP(y) % GMP_NUMB_BITS;
+ sh = sh <= 0 ? - sh : GMP_NUMB_BITS - sh;
+ MPFR_ASSERTD (sh >= 0);
+ if (precy + sh <= precx) /* we can copy directly */
+ {
+ mp_size_t ds;
+
+ MPFR_ASSERTN (sx >= sy);
+ ds = sx - sy;
+
+ if (sh != 0)
+ {
+ mp_limb_t out;
+ out = mpn_rshift (xp + ds, MPFR_MANT(y), sy, sh);
+ MPFR_ASSERTN (ds > 0 || out == 0);
+ if (ds > 0)
+ xp[--ds] = out;
+ }
+ else
+ MPN_COPY (xp + ds, MPFR_MANT (y), sy);
+ if (ds > 0)
+ MPN_ZERO (xp, ds);
+ EXP(x) = (MPFR_GET_EXP(y) + sh) / GMP_NUMB_BITS;
+ inex = 0;
+ }
+ else /* we have to round to precx - sh bits */
+ {
+ mpfr_t z;
+ mp_size_t sz;
+
+ /* Recall that precx = (mpfr_prec_t) sx * GMP_NUMB_BITS, thus removing
+ sh bits (sh < GMP_NUMB_BITSS) won't reduce the number of limbs. */
+ mpfr_init2 (z, precx - sh);
+ sz = MPFR_LIMB_SIZE (z);
+ MPFR_ASSERTN (sx == sz);
+
+ inex = mpfr_set (z, y, rnd_mode);
+ /* warning, sh may change due to rounding, but then z is a power of two,
+ thus we can safely ignore its last bit which is 0 */
+ sh = MPFR_GET_EXP(z) % GMP_NUMB_BITS;
+ sh = sh <= 0 ? - sh : GMP_NUMB_BITS - sh;
+ MPFR_ASSERTD (sh >= 0);
+ if (sh != 0)
+ {
+ mp_limb_t out;
+ out = mpn_rshift (xp, MPFR_MANT(z), sz, sh);
+ /* If sh hasn't changed, it is the number of the non-significant
+ bits in the lowest limb of z. Therefore out == 0. */
+ MPFR_ASSERTD (out == 0); (void) out; /* avoid a warning */
+ }
+ else
+ MPN_COPY (xp, MPFR_MANT(z), sz);
+ EXP(x) = (MPFR_GET_EXP(z) + sh) / GMP_NUMB_BITS;
+ mpfr_clear (z);
+ }
+
+ /* set size and sign */
+ SIZ(x) = (MPFR_FROM_SIGN_TO_INT(MPFR_SIGN(y)) < 0) ? -sx : sx;
+
+ return inex;
+}