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      1 /* $NetBSD: flt_rounds.c,v 1.2 2022/04/08 10:17:52 andvar Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2014 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Matt Thomas of 3am Software Foundry.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 __RCSID("$NetBSD: flt_rounds.c,v 1.2 2022/04/08 10:17:52 andvar Exp $");
     35 #endif /* LIBC_SCCS and not lint */
     36 
     37 #include <sys/param.h>
     38 #include <sys/types.h>
     39 #include <ieeefp.h>
     40 
     41 #include <aarch64/armreg.h>
     42 
     43 
     44 /*
     45  * Return the current FP rounding mode
     46  *
     47  * Returns:
     48  *	0 - round to zero
     49  *	1 - round to nearest
     50  *	2 - round to positive infinity
     51  *	3 - round to negative infinity
     52  *
     53  * However, the rounding modes stored in the FPCR are:
     54  *	0 - round to nearest
     55  *	1 - round to positive infinity
     56  *	2 - round to negative infinity
     57  *	3 - round to zero
     58  *
     59  * To convert, just add 1 and then mask with 3.
     60  */
     61 
     62 int __flt_rounds(void);
     63 
     64 int
     65 __flt_rounds(void)
     66 {
     67 	return (__SHIFTOUT(reg_fpcr_read(), FPCR_RMODE) + 1) & 3;
     68 }
     69