Add incomplet long double math support to libmingwex.a

winsup/mingw/mingwex/math/roundl.c

@@ -0,0 +1,30 @@
+#include <fenv.h>
+
+long double
+roundl (long double x) {
+  long double retval;
+  unsigned short saved_cw, _cw;
+  __asm__ (
+	"fnstcw %0;"
+  	: "=m" (saved_cw)
+	); /* save  control word  */
+  _cw = ~(FE_TONEAREST | FE_DOWNWARD | FE_UPWARD | FE_TOWARDZERO)
+     	  | (x > 0.0 ? FE_UPWARD : FE_DOWNWARD); /* round away from zero */
+  __asm__ (
+	"fldcw %0;"
+	:
+	: "m" (_cw)
+	);  /* load the rounding control */
+  __asm__ (
+	"frndint;"
+	: "=t" (retval)
+	: "0" (x)
+	); /* do the rounding */
+  __asm__ (
+	"fldcw %0;"
+	:
+	: "m" (saved_cw)
+	); /* restore control word */
+  return retval;
+}
+