Add an implementation of fenv.h intended for platforms that lack an FPU and

use softfloat.

Thanks to Ian Lepore for testing and debugging this patch.  The fenv
regression tests pass (at least for Ian's arm chip) with this change.

lib/msun/Makefile

@@ -125,7 +125,7 @@ XRINT_CFLAGS:=	${.IMPSRC:M*/s_nearbyint.c:C/^.+$/${XRINT_CFLAGS}/:C/^$//}
 
 SRCS=	${COMMON_SRCS} ${ARCH_SRCS}
 
-INCS=	fenv.h math.h
+INCS+=	fenv.h math.h
 
 MAN=	acos.3 acosh.3 asin.3 asinh.3 atan.3 atan2.3 atanh.3 \
 	ceil.3 ccos.3 ccosh.3 cexp.3 \

lib/msun/arm/Makefile.inc

@@ -1,4 +1,5 @@
 # $FreeBSD$
 
+INCS += fenv-softfloat.h
 LDBL_PREC = 53
 SYM_MAPS += ${.CURDIR}/arm/Symbol.map

lib/msun/arm/fenv.h

@@ -64,13 +64,25 @@ extern const fenv_t	__fe_dfl_env;
 #define _FPUSW_SHIFT	16
 #define	_ENABLE_MASK	(FE_ALL_EXCEPT << _FPUSW_SHIFT)
 
-#ifdef	ARM_HARD_FLOAT
+#ifndef	ARM_HARD_FLOAT
+/*
+ * The following macros map between the softfloat emulator's flags and
+ * the hardware's FPSR.  The hardware this file was written for doesn't
+ * have rounding control bits, so we stick those in the system ID byte.
+ */
+#define	__set_env(env, flags, mask, rnd) env = ((flags)			\
+						| (mask)<<_FPUSW_SHIFT	\
+						| (rnd) << 24)
+#define	__env_flags(env)		((env) & FE_ALL_EXCEPT)
+#define	__env_mask(env)			(((env) >> _FPUSW_SHIFT)	\
+						& FE_ALL_EXCEPT)
+#define	__env_round(env)		(((env) >> 24) & _ROUND_MASK)
+#include <fenv-softfloat.h>
+
+#else	/* ARM_HARD_FLOAT */
+
 #define	__rfs(__fpsr)	__asm __volatile("rfs %0" : "=r" (*(__fpsr)))
 #define	__wfs(__fpsr)	__asm __volatile("wfs %0" : : "r" (__fpsr))
-#else
-#define __rfs(__fpsr)
-#define __wfs(__fpsr)
-#endif
 
 __fenv_static inline int
 feclearexcept(int __excepts)
@@ -218,6 +230,8 @@ fegetexcept(void)
 
 #endif /* __BSD_VISIBLE */
 
+#endif	/* ARM_HARD_FLOAT */
+
 __END_DECLS
 
 #endif	/* !_FENV_H_ */

lib/msun/src/fenv-softfloat.h

@@ -0,0 +1,184 @@
+/*-
+ * Copyright (c) 2004-2011 David Schultz <das@FreeBSD.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.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef	_FENV_H_
+#error "This file is meant to be included only by <fenv.h>."
+#endif
+
+/*
+ * This file implements the functionality of <fenv.h> on platforms that
+ * lack an FPU and use softfloat in libc for floating point.  To use it,
+ * you must write an <fenv.h> that provides the following:
+ *
+ *   - a typedef for fenv_t, which may be an integer or struct type
+ *   - a typedef for fexcept_t (XXX This file assumes fexcept_t is a
+ *     simple integer type containing the exception mask.)
+ *   - definitions of FE_* constants for the five exceptions and four
+ *     rounding modes in IEEE 754, as described in fenv(3)
+ *   - a definition, and the corresponding external symbol, for FE_DFL_ENV
+ *   - a macro __set_env(env, flags, mask, rnd), which sets the given fenv_t
+ *     from the exception flags, mask, and rounding mode
+ *   - macros __env_flags(env), __env_mask(env), and __env_round(env), which
+ *     extract fields from an fenv_t
+ *   - a definition of __fenv_static
+ *
+ * If the architecture supports an optional FPU, it's recommended that you
+ * define fenv_t and fexcept_t to match the hardware ABI.  Otherwise, it
+ * doesn't matter how you define them.
+ */
+
+extern int __softfloat_float_exception_flags;
+extern int __softfloat_float_exception_mask;
+extern int __softfloat_float_rounding_mode;
+void __softfloat_float_raise(int);
+
+__fenv_static inline int
+feclearexcept(int __excepts)
+{
+
+	__softfloat_float_exception_flags &= ~__excepts;
+	return (0);
+}
+
+__fenv_static inline int
+fegetexceptflag(fexcept_t *__flagp, int __excepts)
+{
+
+	*__flagp = __softfloat_float_exception_flags & __excepts;
+	return (0);
+}
+
+__fenv_static inline int
+fesetexceptflag(const fexcept_t *__flagp, int __excepts)
+{
+
+	__softfloat_float_exception_flags &= ~__excepts;
+	__softfloat_float_exception_flags |= *__flagp & __excepts;
+	return (0);
+}
+
+__fenv_static inline int
+feraiseexcept(int __excepts)
+{
+
+	__softfloat_float_raise(__excepts);
+	return (0);
+}
+
+__fenv_static inline int
+fetestexcept(int __excepts)
+{
+
+	return (__softfloat_float_exception_flags & __excepts);
+}
+
+__fenv_static inline int
+fegetround(void)
+{
+
+	return (__softfloat_float_rounding_mode);
+}
+
+__fenv_static inline int
+fesetround(int __round)
+{
+
+	__softfloat_float_rounding_mode = __round;
+	return (0);
+}
+
+__fenv_static inline int
+fegetenv(fenv_t *__envp)
+{
+
+	__set_env(*__envp, __softfloat_float_exception_flags,
+	    __softfloat_float_exception_mask, __softfloat_float_rounding_mode);
+	return (0);
+}
+
+__fenv_static inline int
+feholdexcept(fenv_t *__envp)
+{
+	fenv_t __env;
+
+	fegetenv(__envp);
+	__softfloat_float_exception_flags = 0;
+	__softfloat_float_exception_mask = 0;
+	return (0);
+}
+
+__fenv_static inline int
+fesetenv(const fenv_t *__envp)
+{
+
+	__softfloat_float_exception_flags = __env_flags(*__envp);
+	__softfloat_float_exception_mask = __env_mask(*__envp);
+	__softfloat_float_rounding_mode = __env_round(*__envp);
+	return (0);
+}
+
+__fenv_static inline int
+feupdateenv(const fenv_t *__envp)
+{
+	int __oflags = __softfloat_float_exception_flags;
+
+	fesetenv(__envp);
+	feraiseexcept(__oflags);
+	return (0);
+}
+
+#if __BSD_VISIBLE
+
+/* We currently provide no external definitions of the functions below. */
+
+static inline int
+feenableexcept(int __mask)
+{
+	int __omask = __softfloat_float_exception_mask;
+
+	__softfloat_float_exception_mask |= __mask;
+	return (__omask);
+}
+
+static inline int
+fedisableexcept(int __mask)
+{
+	int __omask = __softfloat_float_exception_mask;
+
+	__softfloat_float_exception_mask &= ~__mask;
+	return (__omask);
+}
+
+static inline int
+fegetexcept(void)
+{
+
+	return (__softfloat_float_exception_mask);
+}
+
+#endif /* __BSD_VISIBLE */