1 files changed, 150 insertions, 0 deletions
diff --git a/src/next.c b/src/next.c
new file mode 100644
index 0000000..849d206
--- /dev/null
+++ b/src/next.c
@@ -0,0 +1,150 @@
+/* mpfr_nextabove, mpfr_nextbelow, mpfr_nexttoward -- next representable
+floating-point number
+
+Copyright 1999, 2001, 2002, 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"
+
+void
+mpfr_nexttozero (mpfr_ptr x)
+{
+  if (MPFR_UNLIKELY(MPFR_IS_INF(x)))
+    {
+      mpfr_setmax (x, __gmpfr_emax);
+      return;
+    }
+  else if (MPFR_UNLIKELY( MPFR_IS_ZERO(x) ))
+    {
+      MPFR_CHANGE_SIGN(x);
+      mpfr_setmin (x, __gmpfr_emin);
+    }
+  else
+    {
+      mp_size_t xn;
+      int sh;
+      mp_limb_t *xp;
+
+      xn = MPFR_LIMB_SIZE (x);
+      MPFR_UNSIGNED_MINUS_MODULO (sh, MPFR_PREC(x));
+      xp = MPFR_MANT(x);
+      mpn_sub_1 (xp, xp, xn, MPFR_LIMB_ONE << sh);
+      if (MPFR_UNLIKELY( MPFR_LIMB_MSB(xp[xn-1]) == 0) )
+        { /* was an exact power of two: not normalized any more */
+          mpfr_exp_t exp = MPFR_EXP (x);
+          if (MPFR_UNLIKELY(exp == __gmpfr_emin))
+            MPFR_SET_ZERO(x);
+          else
+            {
+              mp_size_t i;
+              MPFR_SET_EXP (x, exp - 1);
+              xp[0] = MP_LIMB_T_MAX << sh;
+              for (i = 1; i < xn; i++)
+                xp[i] = MP_LIMB_T_MAX;
+            }
+        }
+    }
+}
+
+void
+mpfr_nexttoinf (mpfr_ptr x)
+{
+  if (MPFR_UNLIKELY(MPFR_IS_INF(x)))
+    return;
+  else if (MPFR_UNLIKELY(MPFR_IS_ZERO(x)))
+    mpfr_setmin (x, __gmpfr_emin);
+  else
+    {
+      mp_size_t xn;
+      int sh;
+      mp_limb_t *xp;
+
+      xn = MPFR_LIMB_SIZE (x);
+      MPFR_UNSIGNED_MINUS_MODULO (sh, MPFR_PREC(x));
+      xp = MPFR_MANT(x);
+      if (MPFR_UNLIKELY( mpn_add_1 (xp, xp, xn, MPFR_LIMB_ONE << sh)) )
+        /* got 1.0000... */
+        {
+          mpfr_exp_t exp = MPFR_EXP (x);
+          if (MPFR_UNLIKELY(exp == __gmpfr_emax))
+            MPFR_SET_INF(x);
+          else
+            {
+              MPFR_SET_EXP (x, exp + 1);
+              xp[xn-1] = MPFR_LIMB_HIGHBIT;
+            }
+        }
+    }
+}
+
+void
+mpfr_nextabove (mpfr_ptr x)
+{
+  if (MPFR_UNLIKELY(MPFR_IS_NAN(x)))
+    {
+      __gmpfr_flags |= MPFR_FLAGS_NAN;
+      return;
+    }
+  if (MPFR_IS_NEG(x))
+    mpfr_nexttozero (x);
+  else
+    mpfr_nexttoinf (x);
+}
+
+void
+mpfr_nextbelow (mpfr_ptr x)
+{
+  if (MPFR_UNLIKELY(MPFR_IS_NAN(x)))
+    {
+      __gmpfr_flags |= MPFR_FLAGS_NAN;
+      return;
+    }
+
+  if (MPFR_IS_NEG(x))
+    mpfr_nexttoinf (x);
+  else
+    mpfr_nexttozero (x);
+}
+
+void
+mpfr_nexttoward (mpfr_ptr x, mpfr_srcptr y)
+{
+  int s;
+
+  if (MPFR_UNLIKELY(MPFR_IS_NAN(x)))
+    {
+      __gmpfr_flags |= MPFR_FLAGS_NAN;
+      return;
+    }
+  else if (MPFR_UNLIKELY(MPFR_IS_NAN(x) || MPFR_IS_NAN(y)))
+    {
+      MPFR_SET_NAN(x);
+      __gmpfr_flags |= MPFR_FLAGS_NAN;
+      return;
+    }
+
+  s = mpfr_cmp (x, y);
+  if (s == 0)
+    return;
+  else if (s < 0)
+    mpfr_nextabove (x);
+  else
+    mpfr_nextbelow (x);
+}