1 files changed, 48 insertions, 0 deletions
diff --git a/sysdeps/i386/fpu/s_fdim.c b/sysdeps/i386/fpu/s_fdim.c
new file mode 100644
index 0000000000..b8fefe7d18
--- /dev/null
+++ b/sysdeps/i386/fpu/s_fdim.c
@@ -0,0 +1,48 @@
+/* Return positive difference between arguments.  i386 version.
+   Copyright (C) 1997-2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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 <errno.h>
+#include <fpu_control.h>
+#include <math.h>
+#include <math-narrow-eval.h>
+#include <math_private.h>
+#include <libm-alias-double.h>
+
+double
+__fdim (double x, double y)
+{
+  if (islessequal (x, y))
+    return 0.0;
+
+  /* To avoid double rounding, set double precision for the
+     subtraction.  math_narrow_eval is still needed to eliminate
+     excess range in the case of overflow.  If the result of the
+     subtraction is in the subnormal range for double, it is exact, so
+     no issues of double rounding for subnormals arise.  */
+  fpu_control_t cw, cw_double;
+  _FPU_GETCW (cw);
+  cw_double = (cw & ~_FPU_EXTENDED) | _FPU_DOUBLE;
+  _FPU_SETCW (cw_double);
+  double r = math_narrow_eval (x - y);
+  _FPU_SETCW (cw);
+  if (isinf (r) && !isinf (x) && !isinf (y))
+    __set_errno (ERANGE);
+
+  return r;
+}
+libm_alias_double (__fdim, fdim)