1 /* $OpenBSD: flt_rounds.c,v 1.3 2006/02/06 17:03:17 jmc Exp $ */ 2 /* $NetBSD: flt_rounds.c,v 1.1 2000/12/29 20:13:48 bjh21 Exp $ */ 3 4 /* 5 * Copyright (c) 1996 Mark Brinicombe 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 Mark Brinicombe 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 <ieeefp.h> 37 38 static const int map[] = { 39 1, /* round to nearest */ 40 2, /* round to positive infinity */ 41 3, /* round to negative infinity */ 42 0 /* round to zero */ 43 }; 44 45 /* 46 * Return the current FP rounding mode 47 * 48 * Returns: 49 * 0 - round to zero 50 * 1 - round to nearest 51 * 2 - round to postive infinity 52 * 3 - round to negative infinity 53 * 54 * ok all we need to do is get the current FP rounding mode 55 * index our map table and return the appropriate value. 56 * 57 * HOWEVER: 58 * The ARM FPA codes the rounding mode into the actual FP instructions 59 * so there is no such thing as a global rounding mode. 60 * The default is round to nearest if rounding is not explicitly specified. 61 * FP instructions generated by GCC will not explicitly specify a rounding 62 * mode. 63 * 64 * So the best we can do it to return the rounding mode FP instructions 65 * use if rounding is not specified which is round to nearest. 66 * 67 * This could change in the future with new floating point emulators or 68 * soft float FP libraries. 69 */ 70 71 int __flt_rounds(void); 72 73 int 74 __flt_rounds() 75 { 76 return(map[fpgetround()]); 77 } 78