headers/posix/arch/x86_64/fenv.h

   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 #ifndef _FENV_H_
  30 #define _FENV_H_
  31
  32 #include <stdint.h>
  33 #include <sys/cdefs.h>
  34 #include <sys/types.h>
  35
  36 typedef struct {
  37         struct {
  38                 uint32_t        __control;
  39                 uint32_t        __status;
  40                 uint32_t        __tag;
  41                 char            __other[16];
  42         } __x87;
  43         uint32_t                __mxcsr;
  44 } fenv_t;
  45
  46 typedef uint16_t        fexcept_t;
  47
  48 /* Exception flags */
  49 #define FE_INVALID      0x01
  50 #define FE_DENORMAL     0x02
  51 #define FE_DIVBYZERO    0x04
  52 #define FE_OVERFLOW     0x08
  53 #define FE_UNDERFLOW    0x10
  54 #define FE_INEXACT      0x20
  55 #define FE_ALL_EXCEPT   (FE_DIVBYZERO | FE_DENORMAL | FE_INEXACT | \
  56                          FE_INVALID | FE_OVERFLOW | FE_UNDERFLOW)
  57
  58 /* Rounding modes */
  59 #define FE_TONEAREST    0x0000
  60 #define FE_DOWNWARD     0x0400
  61 #define FE_UPWARD       0x0800
  62 #define FE_TOWARDZERO   0x0c00
  63 #define _ROUND_MASK     (FE_TONEAREST | FE_DOWNWARD | \
  64                          FE_UPWARD | FE_TOWARDZERO)
  65
  66 /*
  67  * As compared to the x87 control word, the SSE unit's control word
  68  * has the rounding control bits offset by 3 and the exception mask
  69  * bits offset by 7.
  70  */
  71 #define _SSE_ROUND_SHIFT        3
  72 #define _SSE_EMASK_SHIFT        7
  73
  74 __BEGIN_DECLS
  75
  76 /* Default floating-point environment */
  77 extern const fenv_t     __fe_dfl_env;
  78 #define FE_DFL_ENV      (&__fe_dfl_env)
  79
  80 #define __fldcw(__cw)           __asm __volatile("fldcw %0" : : "m" (__cw))
  81 #define __fldenv(__env)         __asm __volatile("fldenv %0" : : "m" (__env))
  82 #define __fldenvx(__env)        __asm __volatile("fldenv %0" : : "m" (__env)  \
  83                                 : "st", "st(1)", "st(2)", "st(3)", "st(4)",   \
  84                                 "st(5)", "st(6)", "st(7)")
  85 #define __fnclex()              __asm __volatile("fnclex")
  86 #define __fnstenv(__env)        __asm __volatile("fnstenv %0" : "=m" (*(__env)))
  87 #define __fnstcw(__cw)          __asm __volatile("fnstcw %0" : "=m" (*(__cw)))
  88 #define __fnstsw(__sw)          __asm __volatile("fnstsw %0" : "=am" (*(__sw)))
  89 #define __fwait()               __asm __volatile("fwait")
  90 #define __ldmxcsr(__csr)        __asm __volatile("ldmxcsr %0" : : "m" (__csr))
  91 #define __stmxcsr(__csr)        __asm __volatile("stmxcsr %0" : "=m" (*(__csr)))
  92
  93 static __inline int
  94 feclearexcept(int __excepts)
  95 {
  96         fenv_t __env;
  97
  98         if (__excepts == FE_ALL_EXCEPT) {
  99                 __fnclex();
 100         } else {
 101                 __fnstenv(&__env.__x87);
 102                 __env.__x87.__status &= ~__excepts;
 103                 __fldenv(__env.__x87);
 104         }
 105         __stmxcsr(&__env.__mxcsr);
 106         __env.__mxcsr &= ~__excepts;
 107         __ldmxcsr(__env.__mxcsr);
 108         return (0);
 109 }
 110
 111 static __inline int
 112 fegetexceptflag(fexcept_t *__flagp, int __excepts)
 113 {
 114         uint32_t __mxcsr;
 115         uint16_t __status;
 116
 117         __stmxcsr(&__mxcsr);
 118         __fnstsw(&__status);
 119         *__flagp = (__mxcsr | __status) & __excepts;
 120         return (0);
 121 }
 122
 123 int fesetexceptflag(const fexcept_t *__flagp, int __excepts);
 124 int feraiseexcept(int __excepts);
 125
 126 static __inline int
 127 fetestexcept(int __excepts)
 128 {
 129         uint32_t __mxcsr;
 130         uint16_t __status;
 131
 132         __stmxcsr(&__mxcsr);
 133         __fnstsw(&__status);
 134         return ((__status | __mxcsr) & __excepts);
 135 }
 136
 137 static __inline int
 138 fegetround(void)
 139 {
 140         uint16_t __control;
 141
 142         /*
 143          * We assume that the x87 and the SSE unit agree on the
 144          * rounding mode.  Reading the control word on the x87 turns
 145          * out to be about 5 times faster than reading it on the SSE
 146          * unit on an Opteron 244.
 147          */
 148         __fnstcw(&__control);
 149         return (__control & _ROUND_MASK);
 150 }
 151
 152 static __inline int
 153 fesetround(int __round)
 154 {
 155         uint32_t __mxcsr;
 156         uint16_t __control;
 157
 158         if (__round & ~_ROUND_MASK)
 159                 return (-1);
 160
 161         __fnstcw(&__control);
 162         __control &= ~_ROUND_MASK;
 163         __control |= __round;
 164         __fldcw(__control);
 165
 166         __stmxcsr(&__mxcsr);
 167         __mxcsr &= ~(_ROUND_MASK << _SSE_ROUND_SHIFT);
 168         __mxcsr |= __round << _SSE_ROUND_SHIFT;
 169         __ldmxcsr(__mxcsr);
 170
 171         return (0);
 172 }
 173
 174 int fegetenv(fenv_t *__envp);
 175 int feholdexcept(fenv_t *__envp);
 176
 177 static __inline int
 178 fesetenv(const fenv_t *__envp)
 179 {
 180
 181         /*
 182          * XXX Using fldenvx() instead of fldenv() tells the compiler that this
 183          * instruction clobbers the i387 register stack.  This happens because
 184          * we restore the tag word from the saved environment.  Normally, this
 185          * would happen anyway and we wouldn't care, because the ABI allows
 186          * function calls to clobber the i387 regs.  However, fesetenv() is
 187          * inlined, so we need to be more careful.
 188          */
 189         __fldenvx(__envp->__x87);
 190         __ldmxcsr(__envp->__mxcsr);
 191         return (0);
 192 }
 193
 194 int feupdateenv(const fenv_t *__envp);
 195
 196 #if __BSD_VISIBLE
 197
 198 int feenableexcept(int __mask);
 199 int fedisableexcept(int __mask);
 200
 201 static __inline int
 202 fegetexcept(void)
 203 {
 204         uint16_t __control;
 205
 206         /*
 207          * We assume that the masks for the x87 and the SSE unit are
 208          * the same.
 209          */
 210         __fnstcw(&__control);
 211         return (~__control & FE_ALL_EXCEPT);
 212 }
 213
 214 #endif /* __BSD_VISIBLE */
 215
 216 __END_DECLS
 217
 218 #endif  /* !_FENV_H_ */