add s390x port

src/fenv/s390x/fenv.c

@@ -0,0 +1,55 @@
+#include <fenv.h>
+
+static inline unsigned get_fpc(void)
+{
+	unsigned fpc;
+	__asm__ __volatile__("efpc %0" : "=r"(fpc));
+	return fpc;
+}
+
+static inline void set_fpc(unsigned fpc)
+{
+	__asm__ __volatile__("sfpc %0" :: "r"(fpc));
+}
+
+int feclearexcept(int mask)
+{
+	mask &= FE_ALL_EXCEPT;
+	set_fpc(get_fpc() & ~mask);
+	return 0;
+}
+
+int feraiseexcept(int mask)
+{
+	mask &= FE_ALL_EXCEPT;
+	set_fpc(get_fpc() | mask);
+	return 0;
+}
+
+int fetestexcept(int mask)
+{
+	return get_fpc() & mask & FE_ALL_EXCEPT;
+}
+
+int fegetround(void)
+{
+	return get_fpc() & 3;
+}
+
+int __fesetround(int r)
+{
+	set_fpc(get_fpc() & ~3L | r);
+	return 0;
+}
+
+int fegetenv(fenv_t *envp)
+{
+	*envp = get_fpc();
+	return 0;
+}
+
+int fesetenv(const fenv_t *envp)
+{
+	set_fpc(envp != FE_DFL_ENV ? *envp : 0);
+	return 0;
+}