gas/flonum.h

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