The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/i386/include/ieeefp.h

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    1 /*-
    2  * Copyright (c) 2003 Peter Wemm.
    3  * Copyright (c) 1990 Andrew Moore, Talke Studio
    4  * All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  * 3. All advertising materials mentioning features or use of this software
   15  *    must display the following acknowledgement:
   16  *      This product includes software developed by the University of
   17  *      California, Berkeley and its contributors.
   18  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      from: @(#) ieeefp.h     1.0 (Berkeley) 9/23/93
   35  * $FreeBSD: stable/9/sys/i386/include/ieeefp.h 175234 2008-01-11 18:59:35Z bde $
   36  */
   37 
   38 #ifndef _MACHINE_IEEEFP_H_
   39 #define _MACHINE_IEEEFP_H_
   40 
   41 /*
   42  * IEEE floating point type, constant and function definitions.
   43  * XXX: FP*FLD and FP*OFF are undocumented pollution.
   44  */
   45 
   46 #ifndef _SYS_CDEFS_H_
   47 #error this file needs sys/cdefs.h as a prerequisite
   48 #endif
   49 
   50 /*
   51  * Rounding modes.
   52  */
   53 typedef enum {
   54         FP_RN=0,        /* round to nearest */
   55         FP_RM,          /* round down towards minus infinity */
   56         FP_RP,          /* round up towards plus infinity */
   57         FP_RZ           /* truncate */
   58 } fp_rnd_t;
   59 
   60 /*
   61  * Precision (i.e., rounding precision) modes.
   62  */
   63 typedef enum {
   64         FP_PS=0,        /* 24 bit (single-precision) */
   65         FP_PRS,         /* reserved */
   66         FP_PD,          /* 53 bit (double-precision) */
   67         FP_PE           /* 64 bit (extended-precision) */
   68 } fp_prec_t;
   69 
   70 #define fp_except_t     int
   71 
   72 /*
   73  * Exception bit masks.
   74  */
   75 #define FP_X_INV        0x01    /* invalid operation */
   76 #define FP_X_DNML       0x02    /* denormal */
   77 #define FP_X_DZ         0x04    /* zero divide */
   78 #define FP_X_OFL        0x08    /* overflow */
   79 #define FP_X_UFL        0x10    /* underflow */
   80 #define FP_X_IMP        0x20    /* (im)precision */
   81 #define FP_X_STK        0x40    /* stack fault */
   82 
   83 /*
   84  * FPU control word bit-field masks.
   85  */
   86 #define FP_MSKS_FLD     0x3f    /* exception masks field */
   87 #define FP_PRC_FLD      0x300   /* precision control field */
   88 #define FP_RND_FLD      0xc00   /* rounding control field */
   89 
   90 /*
   91  * FPU status word bit-field masks.
   92  */
   93 #define FP_STKY_FLD     0x3f    /* sticky flags field */
   94 
   95 /*
   96  * FPU control word bit-field offsets (shift counts).
   97  */
   98 #define FP_MSKS_OFF     0       /* exception masks offset */
   99 #define FP_PRC_OFF      8       /* precision control offset */
  100 #define FP_RND_OFF      10      /* rounding control offset */
  101 
  102 /*
  103  * FPU status word bit-field offsets (shift counts).
  104  */
  105 #define FP_STKY_OFF     0       /* sticky flags offset */
  106 
  107 #ifdef __GNUCLIKE_ASM
  108 
  109 #define __fldcw(addr)   __asm __volatile("fldcw %0" : : "m" (*(addr)))
  110 #define __fldenv(addr)  __asm __volatile("fldenv %0" : : "m" (*(addr)))
  111 #define __fnclex()      __asm __volatile("fnclex")
  112 #define __fnstcw(addr)  __asm __volatile("fnstcw %0" : "=m" (*(addr)))
  113 #define __fnstenv(addr) __asm __volatile("fnstenv %0" : "=m" (*(addr)))
  114 #define __fnstsw(addr)  __asm __volatile("fnstsw %0" : "=m" (*(addr)))
  115 
  116 /*
  117  * Load the control word.  Be careful not to trap if there is a currently
  118  * unmasked exception (ones that will become freshly unmasked are not a
  119  * problem).  This case must be handled by a save/restore of the
  120  * environment or even of the full x87 state.  Accessing the environment
  121  * is very inefficient, so only do it when necessary.
  122  */
  123 static __inline void
  124 __fnldcw(unsigned short _cw, unsigned short _newcw)
  125 {
  126         struct {
  127                 unsigned _cw;
  128                 unsigned _other[6];
  129         } _env;
  130         unsigned short _sw;
  131 
  132         if ((_cw & FP_MSKS_FLD) != FP_MSKS_FLD) {
  133                 __fnstsw(&_sw);
  134                 if (((_sw & ~_cw) & FP_STKY_FLD) != 0) {
  135                         __fnstenv(&_env);
  136                         _env._cw = _newcw;
  137                         __fldenv(&_env);
  138                         return;
  139                 }
  140         }
  141         __fldcw(&_newcw);
  142 }
  143 
  144 static __inline fp_rnd_t
  145 fpgetround(void)
  146 {
  147         unsigned short _cw;
  148 
  149         __fnstcw(&_cw);
  150         return ((fp_rnd_t)((_cw & FP_RND_FLD) >> FP_RND_OFF));
  151 }
  152 
  153 static __inline fp_rnd_t
  154 fpsetround(fp_rnd_t _m)
  155 {
  156         fp_rnd_t _p;
  157         unsigned short _cw, _newcw;
  158 
  159         __fnstcw(&_cw);
  160         _p = (fp_rnd_t)((_cw & FP_RND_FLD) >> FP_RND_OFF);
  161         _newcw = _cw & ~FP_RND_FLD;
  162         _newcw |= (_m << FP_RND_OFF) & FP_RND_FLD;
  163         __fnldcw(_cw, _newcw);
  164         return (_p);
  165 }
  166 
  167 static __inline fp_prec_t
  168 fpgetprec(void)
  169 {
  170         unsigned short _cw;
  171 
  172         __fnstcw(&_cw);
  173         return ((fp_prec_t)((_cw & FP_PRC_FLD) >> FP_PRC_OFF));
  174 }
  175 
  176 static __inline fp_prec_t
  177 fpsetprec(fp_prec_t _m)
  178 {
  179         fp_prec_t _p;
  180         unsigned short _cw, _newcw;
  181 
  182         __fnstcw(&_cw);
  183         _p = (fp_prec_t)((_cw & FP_PRC_FLD) >> FP_PRC_OFF);
  184         _newcw = _cw & ~FP_PRC_FLD;
  185         _newcw |= (_m << FP_PRC_OFF) & FP_PRC_FLD;
  186         __fnldcw(_cw, _newcw);
  187         return (_p);
  188 }
  189 
  190 /*
  191  * Get or set the exception mask.
  192  * Note that the x87 mask bits are inverted by the API -- a mask bit of 1
  193  * means disable for x87 and SSE, but for fp*mask() it means enable.
  194  */
  195 
  196 static __inline fp_except_t
  197 fpgetmask(void)
  198 {
  199         unsigned short _cw;
  200 
  201         __fnstcw(&_cw);
  202         return ((~_cw & FP_MSKS_FLD) >> FP_MSKS_OFF);
  203 }
  204 
  205 static __inline fp_except_t
  206 fpsetmask(fp_except_t _m)
  207 {
  208         fp_except_t _p;
  209         unsigned short _cw, _newcw;
  210 
  211         __fnstcw(&_cw);
  212         _p = (~_cw & FP_MSKS_FLD) >> FP_MSKS_OFF;
  213         _newcw = _cw & ~FP_MSKS_FLD;
  214         _newcw |= (~_m << FP_MSKS_OFF) & FP_MSKS_FLD;
  215         __fnldcw(_cw, _newcw);
  216         return (_p);
  217 }
  218 
  219 static __inline fp_except_t
  220 fpgetsticky(void)
  221 {
  222         unsigned _ex;
  223         unsigned short _sw;
  224 
  225         __fnstsw(&_sw);
  226         _ex = (_sw & FP_STKY_FLD) >> FP_STKY_OFF;
  227         return ((fp_except_t)_ex);
  228 }
  229 
  230 static __inline fp_except_t
  231 fpresetsticky(fp_except_t _m)
  232 {
  233         struct {
  234                 unsigned _cw;
  235                 unsigned _sw;
  236                 unsigned _other[5];
  237         } _env;
  238         fp_except_t _p;
  239 
  240         _m &= FP_STKY_FLD >> FP_STKY_OFF;
  241         _p = fpgetsticky();
  242         if ((_p & ~_m) == _p)
  243                 return (_p);
  244         if ((_p & ~_m) == 0) {
  245                 __fnclex();
  246                 return (_p);
  247         }
  248         __fnstenv(&_env);
  249         _env._sw &= ~_m;
  250         __fldenv(&_env);
  251         return (_p);
  252 }
  253 
  254 #endif /* __GNUCLIKE_ASM */
  255 
  256 /* Suppress prototypes in the MI header. */
  257 #define _IEEEFP_INLINED_        1
  258 
  259 #endif /* !_MACHINE_IEEEFP_H_ */

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