1 /* flonum.h - Floating point package 2 Copyright 1987, 1990, 1991, 1992, 1994, 1996, 2000 3 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 the Free 19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA 20 02111-1307, USA. */ 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 35 #include "bignum.h" 36 37 /***********************************************************************\ 38 * * 39 * Variable precision floating point numbers. * 40 * * 41 * Exponent is the place value of the low littlenum. E.g.: * 42 * If 0: low points to the units littlenum. * 43 * If 1: low points to the LITTLENUM_RADIX littlenum. * 44 * If -1: low points to the 1/LITTLENUM_RADIX littlenum. * 45 * * 46 \***********************************************************************/ 47 48 /* JF: A sign value of 0 means we have been asked to assemble NaN 49 A sign value of 'P' means we've been asked to assemble +Inf 50 A sign value of 'N' means we've been asked to assemble -Inf 51 */ 52 struct FLONUM_STRUCT { 53 LITTLENUM_TYPE *low; /* low order littlenum of a bignum */ 54 LITTLENUM_TYPE *high; /* high order littlenum of a bignum */ 55 LITTLENUM_TYPE *leader; /* -> 1st non-zero littlenum */ 56 /* If flonum is 0.0, leader==low-1 */ 57 long exponent; /* base LITTLENUM_RADIX */ 58 char sign; /* '+' or '-' */ 59 }; 60 61 typedef struct FLONUM_STRUCT FLONUM_TYPE; 62 63 /***********************************************************************\ 64 * * 65 * Since we can (& do) meet with exponents like 10^5000, it * 66 * is silly to make a table of ~ 10,000 entries, one for each * 67 * power of 10. We keep a table where item [n] is a struct * 68 * FLONUM_FLOATING_POINT representing 10^(2^n). We then * 69 * multiply appropriate entries from this table to get any * 70 * particular power of 10. For the example of 10^5000, a table * 71 * of just 25 entries suffices: 10^(2^-12)...10^(2^+12). * 72 * * 73 \***********************************************************************/ 74 75 extern const FLONUM_TYPE flonum_positive_powers_of_ten[]; 76 extern const FLONUM_TYPE flonum_negative_powers_of_ten[]; 77 extern const int table_size_of_flonum_powers_of_ten; 78 /* Flonum_XXX_powers_of_ten[] table has legal indices from 0 to 79 + this number inclusive. */ 80 81 /***********************************************************************\ 82 * * 83 * Declare worker functions. * 84 * * 85 \***********************************************************************/ 86 87 int atof_generic (char **address_of_string_pointer, 88 const char *string_of_decimal_marks, 89 const char *string_of_decimal_exponent_marks, 90 FLONUM_TYPE * address_of_generic_floating_point_number); 91 92 void flonum_copy (FLONUM_TYPE * in, FLONUM_TYPE * out); 93 void flonum_multip (const FLONUM_TYPE * a, const FLONUM_TYPE * b, 94 FLONUM_TYPE * product); 95 96 /***********************************************************************\ 97 * * 98 * Declare error codes. * 99 * * 100 \***********************************************************************/ 101 102 #define ERROR_EXPONENT_OVERFLOW (2) 103