x86_64: add fenv support from glibc

1 files changed, 31 insertions, 0 deletions

diff --git a/libm/x86_64/fegetround.c b/libm/x86_64/fegetround.c
new file mode 100644
index 000000000..d0ca106e9
--- /dev/null
+++ b/libm/x86_64/fegetround.c
@@ -0,0 +1,31 @@
+/* Return current rounding direction.
+   Copyright (C) 1997-2017 Free Software Foundation, Inc.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
+
+   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 <fenv.h>
+
+int
+fegetround (void)
+{
+  int cw;
+  /* We only check the x87 FPU unit.  The SSE unit should be the same
+     - and if it's not the same there's no way to signal it.  */
+
+  __asm__ ("fnstcw %0" : "=m" (*&cw));
+
+  return cw & 0xc00;
+}