1 /* $OpenBSD: flt_rounds.c,v 1.7 2015/10/27 05:54:49 guenther Exp $ */ 2 /* $NetBSD: flt_rounds.c,v 1.1 1995/04/29 05:09:53 cgd Exp $ */ 3 4 /* 5 * Copyright (c) 1995 Christopher G. Demetriou 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by Christopher G. Demetriou 19 * for the NetBSD Project. 20 * 4. The name of the author may not be used to endorse or promote products 21 * derived from this software without specific prior written permission 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 33 */ 34 35 #include <sys/types.h> 36 #include <float.h> 37 38 static const int map[] = { 39 0, /* round to zero */ 40 3, /* round to negative infinity */ 41 1, /* round to nearest */ 42 2 /* round to positive infinity */ 43 }; 44 45 int 46 __flt_rounds() 47 { 48 double fpcrval; 49 u_int64_t old; 50 51 __asm__("trapb"); 52 __asm__("mf_fpcr %0" : "=f" (fpcrval)); 53 __asm__("trapb"); 54 old = *(u_int64_t *)&fpcrval; 55 56 return map[(old >> 58) & 0x3]; 57 } 58 DEF_STRONG(__flt_rounds); 59