flt_rounds.c

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2012 Ian Lepore <[email protected]>
 * 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 <fenv.h>
#include <float.h>

#ifndef __ARM_PCS_VFP
#include "softfloat-for-gcc.h"
#include "milieu.h"
#include "softfloat.h"
#endif

int
__flt_rounds(void)
{
	int mode;

#ifndef __ARM_PCS_VFP
	/*
	 * Translate our rounding modes to the unnamed
	 * manifest constants required by C99 et. al.
	 */
	mode = __softfloat_float_rounding_mode;
#else /* __ARM_PCS_VFP */
	/*
	 * Read the floating-point status and control register
	 */
	__asm __volatile("vmrs %0, fpscr" : "=&r"(mode));
	mode &= _ROUND_MASK;
#endif /* __ARM_PCS_VFP */

	switch (mode) {
	case FE_TOWARDZERO:
		return (0);
	case FE_TONEAREST:
		return (1);
	case FE_UPWARD:
		return (2);
	case FE_DOWNWARD:
		return (3);
	}
	return (-1);
}