--- /dev/null
+/* mpfr_get_ld, mpfr_get_ld_2exp -- convert a multiple precision floating-point
+ number to a machine long double
+
+Copyright 2002, 2003, 2004, 2005, 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 <float.h>
+
+#include "mpfr-impl.h"
+
+#ifndef HAVE_LDOUBLE_IEEE_EXT_LITTLE
+
+long double
+mpfr_get_ld (mpfr_srcptr x, mp_rnd_t rnd_mode)
+{
+
+ if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x)))
+ return (long double) mpfr_get_d (x, rnd_mode);
+ else /* now x is a normal non-zero number */
+ {
+ long double r; /* result */
+ long double m;
+ double s; /* part of result */
+ mp_exp_t sh; /* exponent shift, so that x/2^sh is in the double range */
+ mpfr_t y, z;
+ int sign;
+
+ /* first round x to the target long double precision, so that
+ all subsequent operations are exact (this avoids double rounding
+ problems) */
+ mpfr_init2 (y, MPFR_LDBL_MANT_DIG);
+ mpfr_init2 (z, IEEE_DBL_MANT_DIG);
+
+ mpfr_set (y, x, rnd_mode);
+ sh = MPFR_GET_EXP (y);
+ sign = MPFR_SIGN (y);
+ MPFR_SET_EXP (y, 0);
+ MPFR_SET_POS (y);
+
+ r = 0.0;
+ do {
+ s = mpfr_get_d (y, GMP_RNDN); /* high part of y */
+ r += (long double) s;
+ mpfr_set_d (z, s, GMP_RNDN); /* exact */
+ mpfr_sub (y, y, z, GMP_RNDN); /* exact */
+ } while (!MPFR_IS_ZERO (y));
+
+ mpfr_clear (z);
+ mpfr_clear (y);
+
+ /* we now have to multiply back by 2^sh */
+ MPFR_ASSERTD (r > 0);
+ if (sh != 0)
+ {
+ /* An overflow may occurs (example: 0.5*2^1024) */
+ while (r < 1.0)
+ {
+ r += r;
+ sh--;
+ }
+
+ if (sh > 0)
+ m = 2.0;
+ else
+ {
+ m = 0.5;
+ sh = -sh;
+ }
+
+ for (;;)
+ {
+ if (sh % 2)
+ r = r * m;
+ sh >>= 1;
+ if (sh == 0)
+ break;
+ m = m * m;
+ }
+ }
+ if (sign < 0)
+ r = -r;
+ return r;
+ }
+}
+
+#else
+
+long double
+mpfr_get_ld (mpfr_srcptr x, mp_rnd_t rnd_mode)
+{
+ mpfr_long_double_t ld;
+ mpfr_t tmp;
+ MPFR_SAVE_EXPO_DECL (expo);
+
+ MPFR_SAVE_EXPO_MARK (expo);
+ mpfr_set_emin (-16382-63);
+ mpfr_set_emax (16383);
+
+ mpfr_init2 (tmp, MPFR_LDBL_MANT_DIG);
+ mpfr_subnormalize(tmp, mpfr_set (tmp, x, rnd_mode), rnd_mode);
+ mpfr_prec_round (tmp, 64, GMP_RNDZ); /* exact */
+ if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (tmp)))
+ ld.ld = (long double) mpfr_get_d (tmp, rnd_mode);
+ else
+ {
+ mp_limb_t *tmpmant;
+ mp_exp_t e, denorm;
+
+ tmpmant = MPFR_MANT (tmp);
+ e = MPFR_GET_EXP (tmp);
+ denorm = MPFR_UNLIKELY (e < -16382) ? - e - 16382 + 1 : 0;
+#if BITS_PER_MP_LIMB >= 64
+ ld.s.manl = (tmpmant[0] >> denorm);
+ ld.s.manh = (tmpmant[0] >> denorm) >> 32;
+#elif BITS_PER_MP_LIMB == 32
+ if (MPFR_LIKELY (denorm == 0))
+ {
+ ld.s.manl = tmpmant[0];
+ ld.s.manh = tmpmant[1];
+ }
+ else if (denorm < 32)
+ {
+ ld.s.manl = (tmpmant[0] >> denorm) | (tmpmant[1] << (32 - denorm));
+ ld.s.manh = tmpmant[1] >> denorm;
+ }
+ else /* 32 <= denorm <= 64 */
+ {
+ ld.s.manl = tmpmant[1] >> (denorm - 32);
+ ld.s.manh = 0;
+ }
+#else
+# error "BITS_PER_MP_LIMB must be 32 or >= 64"
+ /* Other values have never been supported anyway. */
+#endif
+ if (MPFR_LIKELY (denorm == 0))
+ {
+ ld.s.exph = (e + 0x3FFE) >> 8;
+ ld.s.expl = (e + 0x3FFE);
+ }
+ else
+ ld.s.exph = ld.s.expl = 0;
+ ld.s.sign = MPFR_IS_NEG (x);
+ }
+
+ mpfr_clear (tmp);
+ MPFR_SAVE_EXPO_FREE (expo);
+ return ld.ld;
+}
+
+#endif
+
+/* contributed by Damien Stehle */
+long double
+mpfr_get_ld_2exp (long *expptr, mpfr_srcptr src, mp_rnd_t rnd_mode)
+{
+ long double ret;
+ mp_exp_t exp;
+ mpfr_t tmp;
+
+ if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (src)))
+ return (long double) mpfr_get_d_2exp (expptr, src, rnd_mode);
+
+ tmp[0] = *src; /* Hack copy mpfr_t */
+ MPFR_SET_EXP (tmp, 0);
+ ret = mpfr_get_ld (tmp, rnd_mode);
+
+ if (MPFR_IS_PURE_FP(src))
+ {
+ exp = MPFR_GET_EXP (src);
+
+ /* rounding can give 1.0, adjust back to 0.5 <= abs(ret) < 1.0 */
+ if (ret == 1.0)
+ {
+ ret = 0.5;
+ exp ++;
+ }
+ else if (ret == -1.0)
+ {
+ ret = -0.5;
+ exp ++;
+ }
+
+ MPFR_ASSERTN ((ret >= 0.5 && ret < 1.0)
+ || (ret <= -0.5 && ret > -1.0));
+ MPFR_ASSERTN (exp >= LONG_MIN && exp <= LONG_MAX);
+ }
+ else
+ exp = 0;
+
+ *expptr = exp;
+ return ret;
+}
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