x86_64: add fenv support from glibc

1 files changed, 37 insertions, 0 deletions

diff --git a/libm/x86_64/feholdexcpt.c b/libm/x86_64/feholdexcpt.c
new file mode 100644
index 000000000..917e5f84b
--- /dev/null
+++ b/libm/x86_64/feholdexcpt.c
@@ -0,0 +1,37 @@
+/* Store current floating-point environment and clear exceptions.
+   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>
+
+int
+feholdexcept (fenv_t *envp)
+{
+  unsigned int mxcsr;
+
+  /* Store the environment.  Recall that fnstenv has a side effect of
+     masking all exceptions.  Then clear all exceptions.  */
+  __asm__ ("fnstenv %0\n\t"
+	   "stmxcsr %1\n\t"
+	   "fnclex"
+	   : "=m" (*envp), "=m" (envp->__mxcsr));
+
+  /* Set the SSE MXCSR register.  */
+  mxcsr = (envp->__mxcsr | 0x1f80) & ~0x3f;
+  __asm__ ("ldmxcsr %0" : : "m" (*&mxcsr));
+
+  return 0;
+}