Implement FLT_ROUNDS for arm. Some (all?) arm FPUs lack support for

dynamic rounding modes, but FPUless chips that use softfloat can support it
because everything is emulated anyway.  (We presently have incomplete
support for hardware FPUs.)

Submitted by:	Ian Lepore

lib/libc/arm/gen/Makefile.inc

@@ -3,4 +3,4 @@
 
 SRCS+=	_ctx_start.S _setjmp.S _set_tp.c alloca.S fabs.c \
 	infinity.c ldexp.c makecontext.c \
-	setjmp.S signalcontext.c sigsetjmp.S divsi3.S
+	setjmp.S signalcontext.c sigsetjmp.S divsi3.S flt_rounds.c

lib/libc/arm/gen/flt_rounds.c

@@ -0,0 +1,63 @@
+/*-
+ * Copyright (c) 2012 Ian Lepore <freebsd@damnhippie.dyndns.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <fenv.h>
+#include <float.h>
+
+#include "softfloat.h"
+
+int
+__flt_rounds(void)
+{
+
+#ifndef ARM_HARD_FLOAT
+	/*
+	 * Translate our rounding modes to the unnamed
+	 * manifest constants required by C99 et. al.
+	 */
+	switch (__softfloat_float_rounding_mode) {
+	case FE_TOWARDZERO:
+		return (0);
+	case FE_TONEAREST:
+		return (1);
+	case FE_UPWARD:
+		return (2);
+	case FE_DOWNWARD:
+		return (3);
+	}
+	return (-1);
+#else /* ARM_HARD_FLOAT */
+	/*
+	 * Apparently, the rounding mode is specified as part of the
+	 * instruction format on ARM, so the dynamic rounding mode is
+	 * indeterminate.  Some FPUs may differ.
+	 */
+	return (-1);
+#endif /* ARM_HARD_FLOAT */
+}

sys/arm/include/float.h

@@ -44,7 +44,11 @@ extern int __flt_rounds(void);
 __END_DECLS
 
 #define FLT_RADIX	2		/* b */
-#define FLT_ROUNDS	-1
+#ifndef	_ARM_HARD_FLOAT
+#define	FLT_ROUNDS	__flt_rounds()
+#else
+#define	FLT_ROUNDS	(-1)
+#endif
 #define	FLT_EVAL_METHOD	(-1)		/* XXX */
 #define	DECIMAL_DIG	17		/* max precision in decimal digits */