xref: /freebsd-10.2-release/lib/libc/arm/gen/fpsetround_vfp.c

/*
 * Copyright (C) 2014 Andrew Turner
 * 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: head/lib/libc/arm/gen/fpsetround_vfp.c 264721 2014-04-21 09:43:22Z andrew $");

#include <sys/types.h>
#include <ieeefp.h>

#ifdef __weak_alias
__weak_alias(fpsetround,_fpsetround)
#endif

fp_rnd_t
fpsetround(fp_rnd_t rnd_dir)
{
	uint32_t old, new;

	__asm __volatile("vmrs %0, fpscr" : "=&r"(old));
	new = old & ~(3 << 22);
	new |= rnd_dir << 22;
	__asm __volatile("vmsr fpscr, %0" : : "r"(new));

	return ((old >> 22) & 3);
}