gnu/usr.bin/as/flonum.h

   1 /* flonum.h - Floating point package
   2
   3    Copyright (C) 1987, 1990, 1991, 1992 Free Software Foundation, Inc.
   4
   5    This file is part of GAS, the GNU Assembler.
   6
   7    GAS is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2, or (at your option)
  10    any later version.
  11
  12    GAS is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with GAS; see the file COPYING.  If not, write to
  19    the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  20 /*
  21  * $FreeBSD$
  22  */
  23
  24
  25 /***********************************************************************\
  26  *                                                                      *
  27  *      Arbitrary-precision floating point arithmetic.                  *
  28  *                                                                      *
  29  *                                                                      *
  30  *      Notation: a floating point number is expressed as               *
  31  *      MANTISSA * (2 ** EXPONENT).                                     *
  32  *                                                                      *
  33  *      If this offends more traditional mathematicians, then           *
  34  *      please tell me your nomenclature for flonums!                   *
  35  *                                                                      *
  36  \***********************************************************************/
  37 #if (__STDC__ != 1) && !defined(const)
  38 #define const /* empty */
  39 #endif
  40
  41 #include "bignum.h"
  42
  43 /***********************************************************************\
  44  *                                                                      *
  45  *      Variable precision floating point numbers.                      *
  46  *                                                                      *
  47  *      Exponent is the place value of the low littlenum. E.g.:         *
  48  *      If  0:  low points to the units             littlenum.          *
  49  *      If  1:  low points to the LITTLENUM_RADIX   littlenum.          *
  50  *      If -1:  low points to the 1/LITTLENUM_RADIX littlenum.          *
  51  *                                                                      *
  52  \***********************************************************************/
  53
  54 /* JF:  A sign value of 0 means we have been asked to assemble NaN
  55    A sign value of 'P' means we've been asked to assemble +Inf
  56    A sign value of 'N' means we've been asked to assemble -Inf
  57    */
  58 struct FLONUM_STRUCT
  59 {
  60         LITTLENUM_TYPE *low;    /* low order littlenum of a bignum */
  61         LITTLENUM_TYPE *high;   /* high order littlenum of a bignum */
  62         LITTLENUM_TYPE *leader; /* -> 1st non-zero littlenum */
  63         /* If flonum is 0.0, leader == low-1 */
  64         long            exponent; /* base LITTLENUM_RADIX */
  65         char                    sign;   /* '+' or '-' */
  66 };
  67
  68 typedef struct FLONUM_STRUCT FLONUM_TYPE;
  69
  70
  71 /***********************************************************************\
  72  *                                                                      *
  73  *      Since we can (& do) meet with exponents like 10^5000, it        *
  74  *      is silly to make a table of ~ 10,000 entries, one for each      *
  75  *      power of 10. We keep a table where item [n] is a struct         *
  76  *      FLONUM_FLOATING_POINT representing 10^(2^n). We then            *
  77  *      multiply appropriate entries from this table to get any         *
  78  *      particular power of 10. For the example of 10^5000, a table     *
  79  *      of just 25 entries suffices: 10^(2^-12)...10^(2^+12).           *
  80  *                                                                      *
  81  \***********************************************************************/
  82
  83
  84 extern const FLONUM_TYPE flonum_positive_powers_of_ten[];
  85 extern const FLONUM_TYPE flonum_negative_powers_of_ten[];
  86 extern const int table_size_of_flonum_powers_of_ten;
  87 /* Flonum_XXX_powers_of_ten[] table has */
  88 /* legal indices from 0 to */
  89 /* + this number inclusive. */
  90
  91
  92
  93 /***********************************************************************\
  94  *                                                                      *
  95  *      Declare worker functions.                                       *
  96  *                                                                      *
  97  \***********************************************************************/
  98
  99 #if __STDC__ == 1
 100
 101 int atof_generic(char **address_of_string_pointer,
 102                  const char *string_of_decimal_marks,
 103                  const char *string_of_decimal_exponent_marks,
 104                  FLONUM_TYPE *address_of_generic_floating_point_number);
 105
 106 void flonum_copy(FLONUM_TYPE *in, FLONUM_TYPE *out);
 107 void flonum_multip(const FLONUM_TYPE *a, const FLONUM_TYPE *b, FLONUM_TYPE *product);
 108
 109 #else /* not __STDC__ */
 110
 111 int atof_generic();
 112 void flonum_copy();
 113 void flonum_multip();
 114
 115 #endif /* not __STDC__ */
 116
 117 /***********************************************************************\
 118  *                                                                      *
 119  *      Declare error codes.                                            *
 120  *                                                                      *
 121  \***********************************************************************/
 122
 123 #define ERROR_EXPONENT_OVERFLOW (2)
 124
 125 /* end of flonum.h */