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) 1990 Andrew Moore, Talke Studio
    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  * 3. All advertising materials mentioning features or use of this software
   14  *    must display the following acknowledgement:
   15  *      This product includes software developed by the University of
   16  *      California, Berkeley and its contributors.
   17  * 4. Neither the name of the University nor the names of its contributors
   18  *    may be used to endorse or promote products derived from this software
   19  *    without specific prior written permission.
   20  *
   21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31  * SUCH DAMAGE.
   32  *
   33  *      from: @(#) ieeefp.h     1.0 (Berkeley) 9/23/93
   34  * $FreeBSD: releng/7.4/sys/i386/include/ieeefp.h 143658 2005-03-15 15:53:39Z das $
   35  */
   36 
   37 /*
   38  *      IEEE floating point type and constant definitions.
   39  */
   40 
   41 #ifndef _MACHINE_IEEEFP_H_
   42 #define _MACHINE_IEEEFP_H_
   43 
   44 #ifndef _SYS_CDEFS_H_
   45 #error this file needs sys/cdefs.h as a prerequisite
   46 #endif
   47 
   48 /*
   49  * FP rounding modes
   50  */
   51 typedef enum {
   52         FP_RN=0,        /* round to nearest */
   53         FP_RM,          /* round down to minus infinity */
   54         FP_RP,          /* round up to plus infinity */
   55         FP_RZ           /* truncate */
   56 } fp_rnd_t;
   57 
   58 /*
   59  * FP precision modes
   60  */
   61 typedef enum {
   62         FP_PS=0,        /* 24 bit (single-precision) */
   63         FP_PRS,         /* reserved */
   64         FP_PD,          /* 53 bit (double-precision) */
   65         FP_PE           /* 64 bit (extended-precision) */
   66 } fp_prec_t;
   67 
   68 #define fp_except_t     int
   69 
   70 /*
   71  * FP exception masks
   72  */
   73 #define FP_X_INV        0x01    /* invalid operation */
   74 #define FP_X_DNML       0x02    /* denormal */
   75 #define FP_X_DZ         0x04    /* zero divide */
   76 #define FP_X_OFL        0x08    /* overflow */
   77 #define FP_X_UFL        0x10    /* underflow */
   78 #define FP_X_IMP        0x20    /* (im)precision */
   79 #define FP_X_STK        0x40    /* stack fault */
   80 
   81 /*
   82  * FP registers
   83  */
   84 #define FP_MSKS_REG     0       /* exception masks */
   85 #define FP_PRC_REG      0       /* precision */
   86 #define FP_RND_REG      0       /* direction */
   87 #define FP_STKY_REG     1       /* sticky flags */
   88 
   89 /*
   90  * FP register bit field masks
   91  */
   92 #define FP_MSKS_FLD     0x3f    /* exception masks field */
   93 #define FP_PRC_FLD      0x300   /* precision control field */
   94 #define FP_RND_FLD      0xc00   /* round control field */
   95 #define FP_STKY_FLD     0x3f    /* sticky flags field */
   96 
   97 /*
   98  * FP register bit field offsets
   99  */
  100 #define FP_MSKS_OFF     0       /* exception masks offset */
  101 #define FP_PRC_OFF      8       /* precision control offset */
  102 #define FP_RND_OFF      10      /* round control offset */
  103 #define FP_STKY_OFF     0       /* sticky flags offset */
  104 
  105 #ifdef __GNUCLIKE_ASM
  106 
  107 #define __fldenv(addr)  __asm __volatile("fldenv %0" : : "m" (*(addr)))
  108 #define __fnstenv(addr) __asm __volatile("fnstenv %0" : "=m" (*(addr)))
  109 #define __fnstcw(addr)  __asm __volatile("fnstcw %0" : "=m" (*(addr)))
  110 #define __fnstsw(addr)  __asm __volatile("fnstsw %0" : "=m" (*(addr)))
  111 
  112 /*
  113  * return the contents of a FP register
  114  */
  115 static __inline__ int
  116 __fpgetreg(int _reg)
  117 {
  118         unsigned short _mem;
  119 
  120         /*-
  121          * This is more efficient than it looks.  The switch gets optimized
  122          * away if _reg is constant.
  123          *
  124          * The default case only supports _reg == 0.  We could handle more
  125          * registers (e.g., tags) using fnstenv, but the interface doesn't
  126          * support more.
  127          */
  128         switch(_reg) {
  129         default:
  130                 __fnstcw(&_mem);
  131                 break;
  132         case FP_STKY_REG:
  133                 __fnstsw(&_mem);
  134                 break;
  135         }
  136         return _mem;
  137 }
  138 
  139 /*
  140  * set a FP mode; return previous mode
  141  */
  142 static __inline__ int
  143 __fpsetreg(int _m, int _reg, int _fld, int _off)
  144 {
  145         unsigned _env[7];
  146         unsigned _p;
  147 
  148         /*
  149          * _reg == 0 could be handled better using fnstcw/fldcw.
  150          */
  151         __fnstenv(_env);
  152         _p =  (_env[_reg] & _fld) >> _off;
  153         _env[_reg] = (_env[_reg] & ~_fld) | (_m << _off & _fld);
  154         __fldenv(_env);
  155         return _p;
  156 }
  157 
  158 #endif /* __GNUCLIKE_ASM */
  159 
  160 /*
  161  * SysV/386 FP control interface
  162  */
  163 #define fpgetround()    ((fp_rnd_t)                                     \
  164         ((__fpgetreg(FP_RND_REG) & FP_RND_FLD) >> FP_RND_OFF))
  165 #define fpsetround(m)   ((fp_rnd_t)                                     \
  166         __fpsetreg((m), FP_RND_REG, FP_RND_FLD, FP_RND_OFF))
  167 #define fpgetprec()     ((fp_prec_t)                                    \
  168         ((__fpgetreg(FP_PRC_REG) & FP_PRC_FLD) >> FP_PRC_OFF))
  169 #define fpsetprec(m)    ((fp_prec_t)                                    \
  170         __fpsetreg((m), FP_PRC_REG, FP_PRC_FLD, FP_PRC_OFF))
  171 #define fpgetmask()     ((fp_except_t)                                  \
  172         ((~__fpgetreg(FP_MSKS_REG) & FP_MSKS_FLD) >> FP_MSKS_OFF))
  173 #define fpsetmask(m)    ((fp_except_t)                                  \
  174         (~__fpsetreg(~(m), FP_MSKS_REG, FP_MSKS_FLD, FP_MSKS_OFF)) &    \
  175             (FP_MSKS_FLD >> FP_MSKS_OFF))
  176 #define fpgetsticky()   ((fp_except_t)                                  \
  177         ((__fpgetreg(FP_STKY_REG) & FP_STKY_FLD) >> FP_STKY_OFF))
  178 #define fpresetsticky(m) ((fp_except_t)                                 \
  179         __fpsetreg(0, FP_STKY_REG, (m), FP_STKY_OFF))
  180 
  181 /* Suppress prototypes in the MI header. */
  182 #define _IEEEFP_INLINED_        1
  183 
  184 #endif /* !_MACHINE_IEEEFP_H_ */

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