From 9d26bc6958f853de9a6239a9b4f548a64acc9e40 Mon Sep 17 00:00:00 2001
From: tcr3dr <tim@3drobotics.com>
Date: Thu, 4 Jun 2015 12:05:42 -0700
Subject: [PATCH] HAL_SITL: Adds polyfill for feenableexcept on OS X.

---
 libraries/AP_HAL_SITL/Scheduler.cpp   |  1 +
 libraries/AP_HAL_SITL/fenv_polyfill.h | 32 +++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)
 create mode 100644 libraries/AP_HAL_SITL/fenv_polyfill.h

diff --git a/libraries/AP_HAL_SITL/Scheduler.cpp b/libraries/AP_HAL_SITL/Scheduler.cpp
index b346c52ad6..6899bdb24f 100644
--- a/libraries/AP_HAL_SITL/Scheduler.cpp
+++ b/libraries/AP_HAL_SITL/Scheduler.cpp
@@ -8,6 +8,7 @@
 #include <sys/time.h>
 #include <unistd.h>
 #include <fenv.h>
+#include "fenv_polyfill.h"
 
 using namespace HALSITL;
 
diff --git a/libraries/AP_HAL_SITL/fenv_polyfill.h b/libraries/AP_HAL_SITL/fenv_polyfill.h
new file mode 100644
index 0000000000..cfa8b9991a
--- /dev/null
+++ b/libraries/AP_HAL_SITL/fenv_polyfill.h
@@ -0,0 +1,32 @@
+
+#ifndef __FENV_POLYFILL_H__
+#define __FENV_POLYFILL_H__
+
+#if (defined __APPLE__) && (defined(__i386__) || defined(__x86_64__))
+
+#include <fenv.h>
+
+// Public domain polyfill for feenableexcept on OS X
+// http://www-personal.umich.edu/~williams/archive/computation/fe-handling-example.c
+
+inline int
+feenableexcept (unsigned int excepts)
+{
+  static fenv_t fenv;
+  unsigned int new_excepts = excepts & FE_ALL_EXCEPT,
+               old_excepts;  // previous masks
+
+  if ( fegetenv (&fenv) ) return -1;
+  old_excepts = fenv.__control & FE_ALL_EXCEPT;
+
+  // unmask
+  fenv.__control &= ~new_excepts;
+  fenv.__mxcsr   &= ~(new_excepts << 7);
+
+  return ( fesetenv (&fenv) ? -1 : old_excepts );
+}
+
+#endif // APPLE
+
+#endif // __FENV_POLYFILL_H__
+