1 files changed, 101 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/ieee754/ldbl-96/s_fma.c b/REORG.TODO/sysdeps/ieee754/ldbl-96/s_fma.c
new file mode 100644
index 0000000000..370592074e
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+++ b/REORG.TODO/sysdeps/ieee754/ldbl-96/s_fma.c
@@ -0,0 +1,101 @@
+/* Compute x * y + z as ternary operation.
+   Copyright (C) 2010-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Jakub Jelinek <jakub@redhat.com>, 2010.
+
+   The GNU C 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 C 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 C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <float.h>
+#include <math.h>
+#include <fenv.h>
+#include <ieee754.h>
+#include <math_private.h>
+
+/* This implementation uses rounding to odd to avoid problems with
+   double rounding.  See a paper by Boldo and Melquiond:
+   http://www.lri.fr/~melquion/doc/08-tc.pdf  */
+
+double
+__fma (double x, double y, double z)
+{
+  if (__glibc_unlikely (isinf (z)))
+    {
+      /* If z is Inf, but x and y are finite, the result should be
+	 z rather than NaN.  */
+      if (isfinite (x) && isfinite (y))
+	return (z + x) + y;
+      return (x * y) + z;
+    }
+
+  /* Ensure correct sign of exact 0 + 0.  */
+  if (__glibc_unlikely ((x == 0 || y == 0) && z == 0))
+    {
+      x = math_opt_barrier (x);
+      return x * y + z;
+    }
+
+  fenv_t env;
+  feholdexcept (&env);
+  fesetround (FE_TONEAREST);
+
+  /* Multiplication m1 + m2 = x * y using Dekker's algorithm.  */
+#define C ((1ULL << (LDBL_MANT_DIG + 1) / 2) + 1)
+  long double x1 = (long double) x * C;
+  long double y1 = (long double) y * C;
+  long double m1 = (long double) x * y;
+  x1 = (x - x1) + x1;
+  y1 = (y - y1) + y1;
+  long double x2 = x - x1;
+  long double y2 = y - y1;
+  long double m2 = (((x1 * y1 - m1) + x1 * y2) + x2 * y1) + x2 * y2;
+
+  /* Addition a1 + a2 = z + m1 using Knuth's algorithm.  */
+  long double a1 = z + m1;
+  long double t1 = a1 - z;
+  long double t2 = a1 - t1;
+  t1 = m1 - t1;
+  t2 = z - t2;
+  long double a2 = t1 + t2;
+  /* Ensure the arithmetic is not scheduled after feclearexcept call.  */
+  math_force_eval (m2);
+  math_force_eval (a2);
+  feclearexcept (FE_INEXACT);
+
+  /* If the result is an exact zero, ensure it has the correct sign.  */
+  if (a1 == 0 && m2 == 0)
+    {
+      feupdateenv (&env);
+      /* Ensure that round-to-nearest value of z + m1 is not reused.  */
+      z = math_opt_barrier (z);
+      return z + m1;
+    }
+
+  fesetround (FE_TOWARDZERO);
+  /* Perform m2 + a2 addition with round to odd.  */
+  a2 = a2 + m2;
+
+  /* Add that to a1 again using rounding to odd.  */
+  union ieee854_long_double u;
+  u.d = a1 + a2;
+  if ((u.ieee.mantissa1 & 1) == 0 && u.ieee.exponent != 0x7fff)
+    u.ieee.mantissa1 |= fetestexcept (FE_INEXACT) != 0;
+  feupdateenv (&env);
+
+  /* Add finally round to double precision.  */
+  return u.d;
+}
+#ifndef __fma
+weak_alias (__fma, fma)
+#endif