1 files changed, 69 insertions, 0 deletions
diff --git a/src/get_si.c b/src/get_si.c
new file mode 100644
index 0000000..f2b2762
--- /dev/null
+++ b/src/get_si.c
@@ -0,0 +1,69 @@
+/* mpfr_get_si -- convert a floating-point number to a signed long.
+
+Copyright 2003, 2004, 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"
+
+long
+mpfr_get_si (mpfr_srcptr f, mpfr_rnd_t rnd)
+{
+  mpfr_prec_t prec;
+  long s;
+  mpfr_t x;
+
+  if (MPFR_UNLIKELY (!mpfr_fits_slong_p (f, rnd)))
+    {
+      MPFR_SET_ERANGE ();
+      return MPFR_IS_NAN (f) ? 0 :
+        MPFR_IS_NEG (f) ? LONG_MIN : LONG_MAX;
+    }
+
+  if (MPFR_IS_ZERO (f))
+    return (long) 0;
+
+  /* determine prec of long */
+  for (s = LONG_MIN, prec = 0; s != 0; s /= 2, prec++)
+    { }
+
+  /* first round to prec bits */
+  mpfr_init2 (x, prec);
+  mpfr_rint (x, f, rnd);
+
+  /* warning: if x=0, taking its exponent is illegal */
+  if (MPFR_UNLIKELY (MPFR_IS_ZERO(x)))
+    s = 0;
+  else
+    {
+      mp_limb_t a;
+      mp_size_t n;
+      mpfr_exp_t exp;
+
+      /* now the result is in the most significant limb of x */
+      exp = MPFR_GET_EXP (x); /* since |x| >= 1, exp >= 1 */
+      n = MPFR_LIMB_SIZE(x);
+      a = MPFR_MANT(x)[n - 1] >> (GMP_NUMB_BITS - exp);
+      s = MPFR_SIGN(f) > 0 ? a : a <= LONG_MAX ? - (long) a : LONG_MIN;
+    }
+
+  mpfr_clear (x);
+
+  return s;
+}