src/system/libroot/posix/arch/x86_64/fenv.c

   1 /*-
   2  * Copyright (c) 2004-2005 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  * $FreeBSD$
  27  */
  28
  29 #include <sys/cdefs.h>
  30 #include <sys/types.h>
  31 #include <posix/fenv.h>
  32 #include <arch/x86_64/fpu.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
  76         __fnstenv(&envp->__x87);
  77         __stmxcsr(&envp->__mxcsr);
  78         /*
  79          * fnstenv masks all exceptions, so we need to restore the
  80          * control word to avoid this side effect.
  81          */
  82         __fldcw(envp->__x87.__control);
  83         return (0);
  84 }
  85
  86 int
  87 feholdexcept(fenv_t *envp)
  88 {
  89         uint32_t mxcsr;
  90
  91         __stmxcsr(&mxcsr);
  92         __fnstenv(&envp->__x87);
  93         __fnclex();
  94         envp->__mxcsr = mxcsr;
  95         mxcsr &= ~FE_ALL_EXCEPT;
  96         mxcsr |= FE_ALL_EXCEPT << _SSE_EMASK_SHIFT;
  97         __ldmxcsr(mxcsr);
  98         return (0);
  99 }
 100
 101 int
 102 feupdateenv(const fenv_t *envp)
 103 {
 104         uint32_t mxcsr;
 105         uint16_t status;
 106
 107         __fnstsw(&status);
 108         __stmxcsr(&mxcsr);
 109         fesetenv(envp);
 110         feraiseexcept((mxcsr | status) & FE_ALL_EXCEPT);
 111         return (0);
 112 }
 113
 114 int
 115 __feenableexcept(int mask)
 116 {
 117         uint32_t mxcsr, omask;
 118         uint16_t control;
 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         uint32_t mxcsr, omask;
 135         uint16_t control;
 136
 137         mask &= FE_ALL_EXCEPT;
 138         __fnstcw(&control);
 139         __stmxcsr(&mxcsr);
 140         omask = ~(control | mxcsr >> _SSE_EMASK_SHIFT) & FE_ALL_EXCEPT;
 141         control |= mask;
 142         __fldcw(control);
 143         mxcsr |= mask << _SSE_EMASK_SHIFT;
 144         __ldmxcsr(mxcsr);
 145         return (omask);
 146 }
 147
 148 __weak_reference(__feenableexcept, feenableexcept);
 149 __weak_reference(__fedisableexcept, fedisableexcept);