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 2, 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 /***********************************************************************\
  21  *                                                                      *
  22  *      Arbitrary-precision floating point arithmetic.                  *
  23  *                                                                      *
  24  *                                                                      *
  25  *      Notation: a floating point number is expressed as               *
  26  *      MANTISSA * (2 ** EXPONENT).                                     *
  27  *                                                                      *
  28  *      If this offends more traditional mathematicians, then           *
  29  *      please tell me your nomenclature for flonums!                   *
  30  *                                                                      *
  31  \***********************************************************************/
  32 #if !defined(__STDC__) && !defined(const)
  33 #define const /* empty */
  34 #endif
  35
  36 #include "bignum.h"
  37
  38 /***********************************************************************\
  39  *                                                                      *
  40  *      Variable precision floating point numbers.                      *
  41  *                                                                      *
  42  *      Exponent is the place value of the low littlenum. E.g.:         *
  43  *      If  0:  low points to the units             littlenum.          *
  44  *      If  1:  low points to the LITTLENUM_RADIX   littlenum.          *
  45  *      If -1:  low points to the 1/LITTLENUM_RADIX littlenum.          *
  46  *                                                                      *
  47  \***********************************************************************/
  48
  49 /* JF:  A sign value of 0 means we have been asked to assemble NaN
  50    A sign value of 'P' means we've been asked to assemble +Inf
  51    A sign value of 'N' means we've been asked to assemble -Inf
  52    */
  53 struct FLONUM_STRUCT
  54 {
  55         LITTLENUM_TYPE *        low;    /* low order littlenum of a bignum */
  56         LITTLENUM_TYPE *        high;   /* high order littlenum of a bignum */
  57         LITTLENUM_TYPE *        leader; /* -> 1st non-zero littlenum */
  58         /* If flonum is 0.0, leader==low-1 */
  59         long            exponent; /* base LITTLENUM_RADIX */
  60         char                    sign;   /* '+' or '-' */
  61 };
  62
  63 typedef struct FLONUM_STRUCT FLONUM_TYPE;
  64
  65
  66 /***********************************************************************\
  67  *                                                                      *
  68  *      Since we can (& do) meet with exponents like 10^5000, it        *
  69  *      is silly to make a table of ~ 10,000 entries, one for each      *
  70  *      power of 10. We keep a table where item [n] is a struct         *
  71  *      FLONUM_FLOATING_POINT representing 10^(2^n). We then            *
  72  *      multiply appropriate entries from this table to get any         *
  73  *      particular power of 10. For the example of 10^5000, a table     *
  74  *      of just 25 entries suffices: 10^(2^-12)...10^(2^+12).           *
  75  *                                                                      *
  76  \***********************************************************************/
  77
  78
  79 extern const FLONUM_TYPE flonum_positive_powers_of_ten[];
  80 extern const FLONUM_TYPE flonum_negative_powers_of_ten[];
  81 extern const int table_size_of_flonum_powers_of_ten;
  82 /* Flonum_XXX_powers_of_ten[] table has */
  83 /* legal indices from 0 to */
  84 /* + this number inclusive. */
  85
  86
  87
  88 /***********************************************************************\
  89  *                                                                      *
  90  *      Declare worker functions.                                       *
  91  *                                                                      *
  92  \***********************************************************************/
  93
  94 #ifdef __STDC__
  95
  96 int atof_generic(char **address_of_string_pointer,
  97                  const char *string_of_decimal_marks,
  98                  const char *string_of_decimal_exponent_marks,
  99                  FLONUM_TYPE *address_of_generic_floating_point_number);
 100
 101 void flonum_copy(FLONUM_TYPE *in, FLONUM_TYPE *out);
 102 void flonum_multip(const FLONUM_TYPE *a, const FLONUM_TYPE *b, FLONUM_TYPE *product);
 103
 104 #else /* __STDC__ */
 105
 106 int atof_generic();
 107 void flonum_copy();
 108 void flonum_multip();
 109
 110 #endif /* __STDC__ */
 111
 112 /***********************************************************************\
 113  *                                                                      *
 114  *      Declare error codes.                                            *
 115  *                                                                      *
 116  \***********************************************************************/
 117
 118 #define ERROR_EXPONENT_OVERFLOW (2)
 119
 120 /* end: flonum.h */