1 /* flonum.h - Floating point package 2 Copyright (C) 1987-2022 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 3, 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 the Free 18 Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA 19 02110-1301, 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 34 #include "bignum.h" 35 36 /***********************************************************************\ 37 * * 38 * Variable precision floating point numbers. * 39 * * 40 * Exponent is the place value of the low littlenum. E.g.: * 41 * If 0: low points to the units littlenum. * 42 * If 1: low points to the LITTLENUM_RADIX littlenum. * 43 * If -1: low points to the 1/LITTLENUM_RADIX littlenum. * 44 * * 45 \***********************************************************************/ 46 47 /* JF: A sign value of 0 means we have been asked to assemble NaN 48 A sign value of 'P' means we've been asked to assemble +Inf 49 A sign value of 'N' means we've been asked to assemble -Inf 50 A sign value of 'Q' means we've been asked to assemble +QNaN 51 A sign value of 'q' means we've been asked to assemble -QNaN 52 A sign value of 'S' means we've been asked to assemble +SNaN 53 A sign value of 's' means we've been asked to assemble -SNaN 54 */ 55 struct FLONUM_STRUCT { 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 * 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 extern const FLONUM_TYPE flonum_positive_powers_of_ten[]; 79 extern const FLONUM_TYPE flonum_negative_powers_of_ten[]; 80 extern const int table_size_of_flonum_powers_of_ten; 81 /* Flonum_XXX_powers_of_ten[] table has legal indices from 0 to 82 + this number inclusive. */ 83 84 /***********************************************************************\ 85 * * 86 * Declare worker functions. * 87 * * 88 \***********************************************************************/ 89 90 int atof_generic (char **address_of_string_pointer, 91 const char *string_of_decimal_marks, 92 const char *string_of_decimal_exponent_marks, 93 FLONUM_TYPE * address_of_generic_floating_point_number); 94 95 void flonum_copy (FLONUM_TYPE * in, FLONUM_TYPE * out); 96 void flonum_multip (const FLONUM_TYPE * a, const FLONUM_TYPE * b, 97 FLONUM_TYPE * product); 98 99 /***********************************************************************\ 100 * * 101 * Declare error codes. * 102 * * 103 \***********************************************************************/ 104 105 #define ERROR_EXPONENT_OVERFLOW (2) 106