fenv.c (2255B)
1 /*- 2 * Copyright (c) 2004 David Schultz <das@FreeBSD.ORG> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD: src/lib/msun/amd64/fenv.c,v 1.2 2004/06/11 02:35:19 das Exp $ 27 */ 28 29 #include <fenv.h> 30 31 int 32 fesetexceptflag(const fexcept_t *flagp, int excepts) 33 { 34 unsigned __mxcsr; 35 36 __stmxcsr(&__mxcsr); 37 __mxcsr &= ~excepts; 38 __mxcsr |= *flagp & excepts; 39 __ldmxcsr(__mxcsr); 40 41 return (0); 42 } 43 44 int 45 feraiseexcept(int excepts) 46 { 47 fexcept_t ex = excepts; 48 49 fesetexceptflag(&ex, excepts); 50 51 // The DIVSS instruction can generate all SSE2 exceptions, 52 // which hopefully means it will check all exception flags. 53 // asm volatile("divss %0,%0" : : "x" (1.0)); 54 55 return (0); 56 } 57 58 int 59 feholdexcept(fenv_t *envp) 60 { 61 int mxcsr; 62 63 __stmxcsr(&mxcsr); 64 *envp = mxcsr; 65 mxcsr &= ~FE_ALL_EXCEPT; 66 mxcsr |= FE_ALL_EXCEPT << 7; 67 __ldmxcsr(mxcsr); 68 return (0); 69 } 70 71 int 72 feupdateenv(const fenv_t *envp) 73 { 74 int mxcsr; 75 76 __stmxcsr(&mxcsr); 77 fesetenv(envp); 78 feraiseexcept(mxcsr & FE_ALL_EXCEPT); 79 return (0); 80 } 81