Imported gcc-4.4.3

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

diff --git a/mpfr/frac.c b/mpfr/frac.c
new file mode 100644 (file)
index 0000000..f43e942
--- /dev/null
+++ b/mpfr/frac.c
@@ -0,0 +1,126 @@
+/* mpfr_frac -- Fractional part of a floating-point number.
+
+Copyright 2002, 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. */
+
+
+#define MPFR_NEED_LONGLONG_H
+#include "mpfr-impl.h"
+
+/* Optimization note: it is not a good idea to call mpfr_integer_p,
+   as some cases will take longer (the number may be parsed twice). */
+
+int
+mpfr_frac (mpfr_ptr r, mpfr_srcptr u, mp_rnd_t rnd_mode)
+{
+  mp_exp_t re, ue;
+  mp_prec_t uq;
+  mp_size_t un, tn, t0;
+  mp_limb_t *up, *tp, k;
+  int sh;
+  mpfr_t tmp;
+  mpfr_ptr t;
+
+  /* Special cases */
+  if (MPFR_UNLIKELY(MPFR_IS_NAN(u)))
+    {
+      MPFR_SET_NAN(r);
+      MPFR_RET_NAN;
+    }
+  else if (MPFR_UNLIKELY(MPFR_IS_INF(u) || mpfr_integer_p (u)))
+    {
+      MPFR_CLEAR_FLAGS(r);
+      MPFR_SET_SAME_SIGN(r, u);
+      MPFR_SET_ZERO(r);
+      MPFR_RET(0);  /* zero is exact */
+    }
+
+  ue = MPFR_GET_EXP (u);
+  if (ue <= 0)  /* |u| < 1 */
+    return mpfr_set (r, u, rnd_mode);
+
+  uq = MPFR_PREC(u);
+  un = (uq - 1) / BITS_PER_MP_LIMB;  /* index of most significant limb */
+  un -= (mp_size_t) (ue / BITS_PER_MP_LIMB);
+  /* now the index of the MSL containing bits of the fractional part */
+
+  up = MPFR_MANT(u);
+  sh = ue % BITS_PER_MP_LIMB;
+  k = up[un] << sh;
+  /* the first bit of the fractional part is the MSB of k */
+
+  if (k != 0)
+    {
+      int cnt;
+
+      count_leading_zeros(cnt, k);
+      /* first bit 1 of the fractional part -> MSB of the number */
+      re = -cnt;
+      sh += cnt;
+      MPFR_ASSERTN (sh < BITS_PER_MP_LIMB);
+      k <<= cnt;
+    }
+  else
+    {
+      re = sh - BITS_PER_MP_LIMB;
+      /* searching for the first bit 1 (exists since u isn't an integer) */
+      while (up[--un] == 0)
+        re -= BITS_PER_MP_LIMB;
+      MPFR_ASSERTN(un >= 0);
+      k = up[un];
+      count_leading_zeros(sh, k);
+      re -= sh;
+      k <<= sh;
+    }
+  /* The exponent of r will be re */
+  /* un: index of the limb of u that contains the first bit 1 of the FP */
+
+  t = (mp_size_t) (MPFR_PREC(r) - 1) / BITS_PER_MP_LIMB < un ?
+    (mpfr_init2 (tmp, (un + 1) * BITS_PER_MP_LIMB), tmp) : r;
+  /* t has enough precision to contain the fractional part of u */
+  /* If we use a temporary variable, we take the non-significant bits
+     of u into account, because of the mpn_lshift below. */
+  MPFR_CLEAR_FLAGS(t);
+  MPFR_SET_SAME_SIGN(t, u);
+  MPFR_SET_EXP (t, re);
+
+  /* Put the fractional part of u into t */
+  tn = (MPFR_PREC(t) - 1) / BITS_PER_MP_LIMB;
+  MPFR_ASSERTN(tn >= un);
+  t0 = tn - un;
+  tp = MPFR_MANT(t);
+  if (sh == 0)
+    MPN_COPY_DECR(tp + t0, up, un + 1);
+  else /* warning: un may be 0 here */
+    tp[tn] = k | ((un) ? mpn_lshift (tp + t0, up, un, sh) : (mp_limb_t) 0);
+  if (t0 > 0)
+    MPN_ZERO(tp, t0);
+
+  if (t != r)
+    { /* t is tmp */
+      int inex;
+
+      inex = mpfr_set (r, t, rnd_mode);
+      mpfr_clear (t);
+      return inex;
+    }
+  else
+    MPFR_RET(0);
+}