gas/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 /***********************************************************************\
  22  *                                                                      *
  23  *      Arbitrary-precision floating point arithmetic.                  *
  24  *                                                                      *
  25  *                                                                      *
  26  *      Notation: a floating point number is expressed as               *
  27  *      MANTISSA * (2 ** EXPONENT).                                     *
  28  *                                                                      *
  29  *      If this offends more traditional mathematicians, then           *
  30  *      please tell me your nomenclature for flonums!                   *
  31  *                                                                      *
  32  \***********************************************************************/
  33 #if (__STDC__ != 1) && !defined(const)
  34 #define const                   /* empty */
  35 #endif
  36
  37 #include "bignum.h"
  38
  39 /***********************************************************************\
  40  *                                                                      *
  41  *      Variable precision floating point numbers.                      *
  42  *                                                                      *
  43  *      Exponent is the place value of the low littlenum. E.g.:         *
  44  *      If  0:  low points to the units             littlenum.          *
  45  *      If  1:  low points to the LITTLENUM_RADIX   littlenum.          *
  46  *      If -1:  low points to the 1/LITTLENUM_RADIX littlenum.          *
  47  *                                                                      *
  48  \***********************************************************************/
  49
  50 /* JF:  A sign value of 0 means we have been asked to assemble NaN
  51    A sign value of 'P' means we've been asked to assemble +Inf
  52    A sign value of 'N' means we've been asked to assemble -Inf
  53    */
  54 struct FLONUM_STRUCT
  55 {
  56   LITTLENUM_TYPE *low;          /* low order littlenum of a bignum */
  57   LITTLENUM_TYPE *high;         /* high order littlenum of a bignum */
  58   LITTLENUM_TYPE *leader;       /* -> 1st non-zero littlenum */
  59   /* If flonum is 0.0, leader==low-1 */
  60   long exponent;                /* base LITTLENUM_RADIX */
  61   char sign;                    /* '+' or '-' */
  62 };
  63
  64 typedef struct FLONUM_STRUCT FLONUM_TYPE;
  65
  66
  67 /***********************************************************************\
  68  *                                                                      *
  69  *      Since we can (& do) meet with exponents like 10^5000, it        *
  70  *      is silly to make a table of ~ 10,000 entries, one for each      *
  71  *      power of 10. We keep a table where item [n] is a struct         *
  72  *      FLONUM_FLOATING_POINT representing 10^(2^n). We then            *
  73  *      multiply appropriate entries from this table to get any         *
  74  *      particular power of 10. For the example of 10^5000, a table     *
  75  *      of just 25 entries suffices: 10^(2^-12)...10^(2^+12).           *
  76  *                                                                      *
  77  \***********************************************************************/
  78
  79
  80 extern const FLONUM_TYPE flonum_positive_powers_of_ten[];
  81 extern const FLONUM_TYPE flonum_negative_powers_of_ten[];
  82 extern const int table_size_of_flonum_powers_of_ten;
  83 /* Flonum_XXX_powers_of_ten[] table has */
  84 /* legal indices from 0 to */
  85 /* + this number inclusive. */
  86
  87
  88
  89 /***********************************************************************\
  90  *                                                                      *
  91  *      Declare worker functions.                                       *
  92  *                                                                      *
  93  \***********************************************************************/
  94
  95 #if __STDC__ == 1
  96
  97 int atof_generic (char **address_of_string_pointer,
  98                   const char *string_of_decimal_marks,
  99                   const char *string_of_decimal_exponent_marks,
 100                   FLONUM_TYPE * address_of_generic_floating_point_number);
 101
 102 void flonum_copy (FLONUM_TYPE * in, FLONUM_TYPE * out);
 103 void flonum_multip (const FLONUM_TYPE * a, const FLONUM_TYPE * b, FLONUM_TYPE * product);
 104
 105 #else /* not __STDC__ */
 106
 107 int atof_generic ();
 108 void flonum_copy ();
 109 void flonum_multip ();
 110
 111 #endif /* not __STDC__ */
 112
 113 /***********************************************************************\
 114  *                                                                      *
 115  *      Declare error codes.                                            *
 116  *                                                                      *
 117  \***********************************************************************/
 118
 119 #define ERROR_EXPONENT_OVERFLOW (2)
 120
 121 /* end of flonum.h */