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      1 /*-
      2  * Copyright (c) 2004-2005 David Schultz <das (at) 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 1.3 2005/03/16 19:03:45 das Exp $
     27  */
     28 
     29 #include <sys/cdefs.h>
     30 #include <sys/types.h>
     31 #include <machine/fpu.h>
     32 #include <fenv.h>
     33 
     34 const fenv_t __fe_dfl_env = {
     35 	{ 0xffff0000 | __INITIAL_FPUCW__,
     36 	  0xffff0000,
     37 	  0xffffffff,
     38 	  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
     39 	    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff }
     40 	},
     41 	__INITIAL_MXCSR__
     42 };
     43 
     44 int
     45 fesetexceptflag(const fexcept_t *flagp, int excepts)
     46 {
     47 	fenv_t env;
     48 
     49 	__fnstenv(&env.__x87);
     50 	env.__x87.__status &= ~excepts;
     51 	env.__x87.__status |= *flagp & excepts;
     52 	__fldenv(env.__x87);
     53 
     54 	__stmxcsr(&env.__mxcsr);
     55 	env.__mxcsr &= ~excepts;
     56 	env.__mxcsr |= *flagp & excepts;
     57 	__ldmxcsr(env.__mxcsr);
     58 
     59 	return (0);
     60 }
     61 
     62 int
     63 feraiseexcept(int excepts)
     64 {
     65 	fexcept_t ex = excepts;
     66 
     67 	fesetexceptflag(&ex, excepts);
     68 	__fwait();
     69 	return (0);
     70 }
     71 
     72 int
     73 fegetenv(fenv_t *envp)
     74 {
     75 	int control;
     76 
     77 	/*
     78 	 * fnstenv masks all exceptions, so we need to save and
     79 	 * restore the control word to avoid this side effect.
     80 	 */
     81 	__fnstcw(&control);
     82 	__fnstenv(&envp->__x87);
     83 	__stmxcsr(&envp->__mxcsr);
     84 	__fldcw(control);
     85 	return (0);
     86 }
     87 
     88 int
     89 feholdexcept(fenv_t *envp)
     90 {
     91 	int mxcsr;
     92 
     93 	__stmxcsr(&mxcsr);
     94 	__fnstenv(&envp->__x87);
     95 	__fnclex();
     96 	envp->__mxcsr = mxcsr;
     97 	mxcsr &= ~FE_ALL_EXCEPT;
     98 	mxcsr |= FE_ALL_EXCEPT << _SSE_EMASK_SHIFT;
     99 	__ldmxcsr(mxcsr);
    100 	return (0);
    101 }
    102 
    103 int
    104 feupdateenv(const fenv_t *envp)
    105 {
    106 	int mxcsr, status;
    107 
    108 	__fnstsw(&status);
    109 	__stmxcsr(&mxcsr);
    110 	fesetenv(envp);
    111 	feraiseexcept((mxcsr | status) & FE_ALL_EXCEPT);
    112 	return (0);
    113 }
    114 
    115 int
    116 __feenableexcept(int mask)
    117 {
    118 	int mxcsr, control, omask;
    119 
    120 	mask &= FE_ALL_EXCEPT;
    121 	__fnstcw(&control);
    122 	__stmxcsr(&mxcsr);
    123 	omask = (control | mxcsr >> _SSE_EMASK_SHIFT) & FE_ALL_EXCEPT;
    124 	control &= ~mask;
    125 	__fldcw(control);
    126 	mxcsr &= ~(mask << _SSE_EMASK_SHIFT);
    127 	__ldmxcsr(mxcsr);
    128 	return (~omask);
    129 }
    130 
    131 int
    132 __fedisableexcept(int mask)
    133 {
    134 	int mxcsr, control, omask;
    135 
    136 	mask &= FE_ALL_EXCEPT;
    137 	__fnstcw(&control);
    138 	__stmxcsr(&mxcsr);
    139 	omask = (control | mxcsr >> _SSE_EMASK_SHIFT) & FE_ALL_EXCEPT;
    140 	control |= mask;
    141 	__fldcw(control);
    142 	mxcsr |= mask << _SSE_EMASK_SHIFT;
    143 	__ldmxcsr(mxcsr);
    144 	return (~omask);
    145 }
    146 
    147 __weak_reference(__feenableexcept, feenableexcept);
    148 __weak_reference(__fedisableexcept, fedisableexcept);
    149