FreeBSD/Linux Kernel Cross Reference
sys/sys/ieee754.h

     /*      $NetBSD: ieee754.h,v 1.17 2020/04/16 22:13:51 christos Exp $    */
     
     /*
      * Copyright (c) 1992, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * This software was developed by the Computer Systems Engineering group
      * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
      * contributed to Berkeley.
     *
     * All advertising materials mentioning features or use of this software
     * must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Lawrence Berkeley Laboratory.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)ieee.h      8.1 (Berkeley) 6/11/93
     */
    #ifndef _SYS_IEEE754_H_
    #define _SYS_IEEE754_H_
    
    /*
     * NOTICE: This is not a standalone file.  To use it, #include it in
     * your port's ieee.h header.
     */
    
    #include <machine/endian.h>
    
    /*
     * <sys/ieee754.h> defines the layout of IEEE 754 floating point types.
     * Only single-precision and double-precision types are defined here;
     * 128-bit long doubles are defined here IFF __HAVE_LONG_DOUBLE equals 128.
     * Otherwise extended types, if available, are defined in the machine-dependent
     * header.
     */
    
    /*
     * Define the number of bits in each fraction and exponent.
     *
     *                   k           k+1
     * Note that  1.0 x 2  == 0.1 x 2      and that denorms are represented
     *
     *                                        (-exp_bias+1)
     * as fractions that look like 0.fffff x 2             .  This means that
     *
     *                       -126
     * the number 0.10000 x 2    , for instance, is the same as the normalized
     *
     *              -127                       -128
     * float 1.0 x 2    .  Thus, to represent 2    , we need one leading zero
     *
     *                                -129
     * in the fraction; to represent 2    , we need two, and so on.  This
     *
     *                                                   (-exp_bias-fracbits+1)
     * implies that the smallest denormalized number is 2
     *
     * for whichever format we are talking about: for single precision, for
     *
     *                                              -126            -149
     * instance, we get .00000000000000000000001 x 2    , or 1.0 x 2    , and
     *
     * -149 == -127 - 23 + 1.
     */
    #define SNG_EXPBITS     8
    #define SNG_FRACBITS    23
    
    struct ieee_single {
    #if _BYTE_ORDER == _BIG_ENDIAN
            unsigned int    sng_sign:1;
            unsigned int    sng_exp:SNG_EXPBITS;
            unsigned int    sng_frac:SNG_FRACBITS;
    #else
            unsigned int    sng_frac:SNG_FRACBITS;
            unsigned int    sng_exp:SNG_EXPBITS;
            unsigned int    sng_sign:1;
   #endif
   };
   
   #define DBL_EXPBITS     11
   #define DBL_FRACHBITS   20
   #define DBL_FRACLBITS   32
   #define DBL_FRACBITS    (DBL_FRACHBITS + DBL_FRACLBITS)
   
   struct ieee_double {
   #if _BYTE_ORDER == _BIG_ENDIAN
           unsigned int    dbl_sign:1;
           unsigned int    dbl_exp:DBL_EXPBITS;
           unsigned int    dbl_frach:DBL_FRACHBITS;
           unsigned int    dbl_fracl:DBL_FRACLBITS;
   #else
           unsigned int    dbl_fracl:DBL_FRACLBITS;
           unsigned int    dbl_frach:DBL_FRACHBITS;
           unsigned int    dbl_exp:DBL_EXPBITS;
           unsigned int    dbl_sign:1;
   #endif
   };
   
   #if __HAVE_LONG_DOUBLE + 0 == 128
   
   #define EXT_EXPBITS     15
   #define EXT_FRACHBITS   48
   #define EXT_FRACLBITS   64
   #define EXT_FRACBITS    (EXT_FRACLBITS + EXT_FRACHBITS)
   
   #define EXT_TO_ARRAY32(u, a) do {                               \
           (a)[0] = (uint32_t)((u).extu_ext.ext_fracl >>  0);      \
           (a)[1] = (uint32_t)((u).extu_ext.ext_fracl >> 32);      \
           (a)[2] = (uint32_t)((u).extu_ext.ext_frach >>  0);      \
           (a)[3] = (uint32_t)((u).extu_ext.ext_frach >> 32);      \
   } while(/*CONSTCOND*/0)
   
   struct ieee_ext {
   #if _BYTE_ORDER == _BIG_ENDIAN
           uint64_t ext_sign:1;
           uint64_t ext_exp:EXT_EXPBITS;
           uint64_t ext_frach:EXT_FRACHBITS;
           uint64_t ext_fracl;
   #else
           uint64_t ext_fracl;
           uint64_t ext_frach:EXT_FRACHBITS;
           uint64_t ext_exp:EXT_EXPBITS;
           uint64_t ext_sign:1;
   #endif
   };
   #endif /* __HAVE_LONG_DOUBLE == 128 */
   
   /*
    * Floats whose exponent is in [1..INFNAN) (of whatever type) are
    * `normal'.  Floats whose exponent is INFNAN are either Inf or NaN.
    * Floats whose exponent is zero are either zero (iff all fraction
    * bits are zero) or subnormal values.
    *
    * At least one `signalling NaN' and one `quiet NaN' value must be
    * implemented.  It is left to the architecture to specify how to
    * distinguish between these.
    */
   #define SNG_EXP_INFNAN  255
   #define DBL_EXP_INFNAN  2047
   #if __HAVE_LONG_DOUBLE + 0 == 128
   #define EXT_EXP_INFNAN  0x7fff
   #endif
   
   /*
    * Exponent biases.
    */
   #define SNG_EXP_BIAS    127
   #define DBL_EXP_BIAS    1023
   #if __HAVE_LONG_DOUBLE + 0 == 128
   #define EXT_EXP_BIAS    16383
   #endif
   
   /*
    * Convenience data structures.
    */
   union ieee_single_u {
           float                   sngu_f;
           struct ieee_single      sngu_sng;
   };
   
   #define sngu_sign       sngu_sng.sng_sign
   #define sngu_exp        sngu_sng.sng_exp
   #define sngu_frac       sngu_sng.sng_frac
   #define SNGU_ZEROFRAC_P(u)      ((u).sngu_frac != 0)
   
   union ieee_double_u {
           double                  dblu_d;
           struct ieee_double      dblu_dbl;
   };
   
   #define dblu_sign       dblu_dbl.dbl_sign
   #define dblu_exp        dblu_dbl.dbl_exp
   #define dblu_frach      dblu_dbl.dbl_frach
   #define dblu_fracl      dblu_dbl.dbl_fracl
   #define DBLU_ZEROFRAC_P(u)      (((u).dblu_frach|(u).dblu_fracl) != 0)
   
   #if __HAVE_LONG_DOUBLE + 0 == 128
   union ieee_ext_u {
           long double             extu_ld;
           struct ieee_ext         extu_ext;
   };
   
   #define extu_exp        extu_ext.ext_exp
   #define extu_sign       extu_ext.ext_sign
   #define extu_fracl      extu_ext.ext_fracl
   #define extu_frach      extu_ext.ext_frach
   #define EXTU_ZEROFRAC_P(u)      (((u).extu_frach|(u).extu_fracl) != 0)
   
   #ifndef LDBL_NBIT
   #define LDBL_IMPLICIT_NBIT      1       /* our NBIT is implicit */
   #endif
   
   #endif /* __HAVE_LONG_DOUBLE */
   
   #endif /* _SYS_IEEE754_H_ */

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