Imported gcc-4.4.3

[msp430-gcc.git] / mpfr / get_f.c

diff --git a/mpfr/get_f.c b/mpfr/get_f.c
new file mode 100644 (file)
index 0000000..bc02679
--- /dev/null
+++ b/mpfr/get_f.c
@@ -0,0 +1,117 @@
+/* mpfr_get_f -- convert a MPFR number to a GNU MPF number
+
+Copyright 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 "mpfr-impl.h"
+
+/* return value is 0 iff no error occurred in the conversion
+   (1 for NaN, +Inf, -Inf that have no equivalent in mpf)
+*/
+int
+mpfr_get_f (mpf_ptr x, mpfr_srcptr y, mp_rnd_t rnd_mode)
+{
+  mp_size_t sx, sy;
+  mp_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 /* NaN or Inf */
+        return 1;
+    }
+
+  sx = PREC(x); /* number of limbs of the mantissa of x */
+
+  precy = MPFR_PREC(y);
+  precx = (mp_prec_t) sx * BITS_PER_MP_LIMB;
+  sy = MPFR_LIMB_SIZE (y);
+
+  xp = PTR (x);
+
+  /* since mpf numbers are represented in base 2^BITS_PER_MP_LIMB,
+     we loose -EXP(y) % BITS_PER_MP_LIMB bits in the most significant limb */
+  sh = MPFR_GET_EXP(y) % BITS_PER_MP_LIMB;
+  sh = sh <= 0 ? - sh : BITS_PER_MP_LIMB - 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) / BITS_PER_MP_LIMB;
+    }
+  else /* we have to round to precx - sh bits */
+    {
+      mpfr_t z;
+      mp_size_t sz, ds;
+
+      /* Recall that precx = (mp_prec_t) sx * BITS_PER_MP_LIMB */
+      mpfr_init2 (z, precx - sh);
+      sz = MPFR_LIMB_SIZE (z);
+      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) % BITS_PER_MP_LIMB;
+      sh = sh <= 0 ? - sh : BITS_PER_MP_LIMB - sh;
+      MPFR_ASSERTD (sx >= sz);
+      ds = sx - sz;
+      MPFR_ASSERTD (sh >= 0 && ds <= 1);
+      if (sh != 0)
+        {
+          mp_limb_t out;
+          out = mpn_rshift (xp + ds, 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);
+        }
+      else
+        MPN_COPY (xp + ds, MPFR_MANT(z), sz);
+      if (ds != 0)
+        xp[0] = 0;
+      EXP(x) = (MPFR_GET_EXP(z) + sh) / BITS_PER_MP_LIMB;
+      mpfr_clear (z);
+    }
+
+  /* set size and sign */
+  SIZ(x) = (MPFR_FROM_SIGN_TO_INT(MPFR_SIGN(y)) < 0) ? -sx : sx;
+
+  return 0;
+}