libguile/ieee-754.h

   1 /* Copyright (C) 1992, 1995, 1996, 1999 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #ifndef SCM_IEEE_754_H
  20 #define SCM_IEEE_754_H 1
  21
  22 /* Based on glibc's <ieee754.h> and modified by Ludovic Courtès to include
  23    all possible IEEE-754 double-precision representations.  */
  24
  25 \f
  26 /* IEEE 754 simple-precision format (32-bit).  */
  27
  28 union scm_ieee754_float
  29   {
  30     float f;
  31
  32     struct
  33       {
  34         unsigned int negative:1;
  35         unsigned int exponent:8;
  36         unsigned int mantissa:23;
  37       } big_endian;
  38
  39     struct
  40       {
  41         unsigned int mantissa:23;
  42         unsigned int exponent:8;
  43         unsigned int negative:1;
  44       } little_endian;
  45   };
  46
  47
  48 \f
  49 /* IEEE 754 double-precision format (64-bit).  */
  50
  51 union scm_ieee754_double
  52   {
  53     double d;
  54
  55     struct
  56       {
  57         /* Big endian.  */
  58
  59         unsigned int negative:1;
  60         unsigned int exponent:11;
  61         /* Together these comprise the mantissa.  */
  62         unsigned int mantissa0:20;
  63         unsigned int mantissa1:32;
  64       } big_endian;
  65
  66     struct
  67       {
  68         /* Both byte order and word order are little endian.  */
  69
  70         /* Together these comprise the mantissa.  */
  71         unsigned int mantissa1:32;
  72         unsigned int mantissa0:20;
  73         unsigned int exponent:11;
  74         unsigned int negative:1;
  75       } little_little_endian;
  76
  77     struct
  78       {
  79         /* Byte order is little endian but word order is big endian.  Not
  80            sure this is very wide spread.  */
  81         unsigned int mantissa0:20;
  82         unsigned int exponent:11;
  83         unsigned int negative:1;
  84         unsigned int mantissa1:32;
  85       } little_big_endian;
  86
  87   };
  88
  89
  90 #endif /* SCM_IEEE_754_H */