1 files changed, 63 insertions, 0 deletions
diff --git a/src/ui_sub.c b/src/ui_sub.c
new file mode 100644
index 000000000..7b775aebb
--- /dev/null
+++ b/src/ui_sub.c
@@ -0,0 +1,63 @@
+/* mpfr_ui_sub -- subtract a floating-point number from an integer
+
+Copyright 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
+Contributed by the Arenaire 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. */
+
+#define MPFR_NEED_LONGLONG_H
+#include "mpfr-impl.h"
+
+int
+mpfr_ui_sub (mpfr_ptr y, unsigned long int u, mpfr_srcptr x, mpfr_rnd_t rnd_mode)
+{
+  mpfr_t uu;
+  mp_limb_t up[1];
+  unsigned long cnt;
+
+  if (MPFR_UNLIKELY (u == 0))
+    return mpfr_neg (y, x, rnd_mode);
+
+  if (MPFR_UNLIKELY(MPFR_IS_SINGULAR(x)))
+    {
+      if (MPFR_IS_NAN(x))
+        {
+          MPFR_SET_NAN(y);
+          MPFR_RET_NAN;
+        }
+      else if (MPFR_IS_INF(x))
+        {
+          /*  u - Inf = -Inf and u - -Inf = +Inf  */
+          MPFR_SET_INF(y);
+          MPFR_SET_OPPOSITE_SIGN(y,x);
+          MPFR_RET(0); /* +/-infinity is exact */
+        }
+      else /* x is zero */
+        /* u - 0 = u */
+        return mpfr_set_ui(y, u, rnd_mode);
+    }
+  else
+    {
+      MPFR_TMP_INIT1 (up, uu, GMP_NUMB_BITS);
+      MPFR_ASSERTN(u == (mp_limb_t) u);
+      count_leading_zeros (cnt, (mp_limb_t) u);
+      *up = (mp_limb_t) u << cnt;
+      MPFR_SET_EXP (uu, GMP_NUMB_BITS - cnt);
+      return mpfr_sub (y, uu, x, rnd_mode);
+    }
+}