x86_64: add fenv support from glibc

1 files changed, 52 insertions, 0 deletions

diff --git a/libm/x86_64/fsetexcptflg.c b/libm/x86_64/fsetexcptflg.c
new file mode 100644
index 000000000..b3f001b7c
--- /dev/null
+++ b/libm/x86_64/fsetexcptflg.c
@@ -0,0 +1,52 @@
+/* Set floating-point environment exception handling.
+   Copyright (C) 2001-2017 Free Software Foundation, Inc.
+
+   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>
+#include <math.h>
+
+int
+fesetexceptflag (const fexcept_t *flagp, int excepts)
+{
+  fenv_t temp;
+  unsigned int mxcsr;
+
+  /* XXX: Do we really need to set both the exception in both units?
+     Shouldn't it be enough to set only the SSE unit?  */
+
+  /* Get the current x87 FPU environment.  We have to do this since we
+     cannot separately set the status word.  */
+  __asm__ ("fnstenv %0" : "=m" (*&temp));
+
+  temp.__status_word &= ~(excepts & FE_ALL_EXCEPT);
+  temp.__status_word |= *flagp & excepts & FE_ALL_EXCEPT;
+
+  /* Store the new status word (along with the rest of the environment.
+     Possibly new exceptions are set but they won't get executed unless
+     the next floating-point instruction.  */
+  __asm__ ("fldenv %0" : : "m" (*&temp));
+
+  /* And now the same for SSE.  */
+  __asm__ ("stmxcsr %0" : "=m" (*&mxcsr));
+
+  mxcsr &= ~(excepts & FE_ALL_EXCEPT);
+  mxcsr |= *flagp & excepts & FE_ALL_EXCEPT;
+
+  __asm__ ("ldmxcsr %0" : : "m" (*&mxcsr));
+
+  /* Success.  */
+  return 0;
+}