crt: Fix return value of fegetexcept(), fedisableexcept() and feenableexcept() functions Function __mingw_controlfp() returns bits for disabled exceptions, but function fegetexcept() must return bits for enabled exceptions. So negate bits for return value. Function __mingw_controlfp() when modifying cw returns new state, but functions fedisableexcept() and feenableexcept() must return old state. So before modifying cw via __mingw_controlfp(), call fegetexcept() to calculate return value of both fedisableexcept() and feenableexcept() functions. Also checks for input argument and return -1 when is invalid. Signed-off-by: LIU Hao <lh_mouse@126.com>

diff --git a/mingw-w64-crt/misc/fedisableexcept.c b/mingw-w64-crt/misc/fedisableexcept.c
index 29b905e..5c3328d 100644
--- a/mingw-w64-crt/misc/fedisableexcept.c
+++ b/mingw-w64-crt/misc/fedisableexcept.c

@@ -4,5 +4,8 @@
 
 int __cdecl fedisableexcept(int excepts)
 {
-  return __mingw_controlfp(excepts & FE_ALL_EXCEPT, excepts & FE_ALL_EXCEPT) & FE_ALL_EXCEPT;
+  if (excepts & ~FE_ALL_EXCEPT) return -1;
+  int old_excepts = fegetexcept();
+  __mingw_controlfp(excepts, excepts);
+  return old_excepts;
 }

diff --git a/mingw-w64-crt/misc/feenableexcept.c b/mingw-w64-crt/misc/feenableexcept.c
index 8a40bd5..7bd6f75 100644
--- a/mingw-w64-crt/misc/feenableexcept.c
+++ b/mingw-w64-crt/misc/feenableexcept.c

@@ -4,5 +4,8 @@
 
 int __cdecl feenableexcept(int excepts)
 {
-  return __mingw_controlfp(0, excepts & FE_ALL_EXCEPT) & FE_ALL_EXCEPT;
+  if (excepts & ~FE_ALL_EXCEPT) return -1;
+  int old_excepts = fegetexcept();
+  __mingw_controlfp(0, excepts);
+  return old_excepts;
 }

diff --git a/mingw-w64-crt/misc/fegetexcept.c b/mingw-w64-crt/misc/fegetexcept.c
index ced9f50..6bbf8d1 100644
--- a/mingw-w64-crt/misc/fegetexcept.c
+++ b/mingw-w64-crt/misc/fegetexcept.c

@@ -4,5 +4,5 @@
 
 int __cdecl fegetexcept(void)
 {
-  return __mingw_controlfp(0, 0) & FE_ALL_EXCEPT;
+  return ~__mingw_controlfp(0, 0) & FE_ALL_EXCEPT;
 }