1 /* mpfr_fits_intmax_p -- test whether an mpfr fits an intmax_t. 2 3 Copyright 2004, 2006-2016 Free Software Foundation, Inc. 4 Contributed by the AriC and Caramba projects, INRIA. 5 6 This file is part of the GNU MPFR Library. 7 8 The GNU MPFR Library is free software; you can redistribute it and/or modify 9 it under the terms of the GNU Lesser General Public License as published by 10 the Free Software Foundation; either version 3 of the License, or (at your 11 option) any later version. 12 13 The GNU MPFR Library is distributed in the hope that it will be useful, but 14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 15 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 16 License for more details. 17 18 You should have received a copy of the GNU Lesser General Public License 19 along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see 20 http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc., 21 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */ 22 23 #ifdef HAVE_CONFIG_H 24 # include "config.h" /* for a build within gmp */ 25 #endif 26 27 #include "mpfr-intmax.h" 28 #include "mpfr-impl.h" 29 30 #ifdef _MPFR_H_HAVE_INTMAX_T 31 32 /* We can't use fits_s.h <= mpfr_cmp_ui */ 33 int 34 mpfr_fits_intmax_p (mpfr_srcptr f, mpfr_rnd_t rnd) 35 { 36 unsigned int saved_flags; 37 mpfr_exp_t e; 38 int prec; 39 mpfr_t x, y; 40 int neg; 41 int res; 42 43 if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (f))) 44 /* Zero always fit */ 45 return MPFR_IS_ZERO (f) ? 1 : 0; 46 47 /* now it fits if either 48 (a) MINIMUM <= f <= MAXIMUM 49 (b) or MINIMUM <= round(f, prec(slong), rnd) <= MAXIMUM */ 50 51 e = MPFR_EXP (f); 52 if (e < 1) 53 return 1; /* |f| < 1: always fits */ 54 55 neg = MPFR_IS_NEG (f); 56 57 /* let EXTREMUM be MAXIMUM if f > 0, and MINIMUM if f < 0 */ 58 59 /* first compute prec(EXTREMUM), this could be done at configure time, 60 but the result can depend on neg (the loop is moved inside the "if" 61 to give the compiler a better chance to compute prec statically) */ 62 if (neg) 63 { 64 uintmax_t s; 65 /* In C89, the division on negative integers isn't well-defined. */ 66 s = SAFE_ABS (uintmax_t, MPFR_INTMAX_MIN); 67 for (prec = 0; s != 0; s /= 2, prec ++); 68 } 69 else 70 { 71 intmax_t s; 72 s = MPFR_INTMAX_MAX; 73 for (prec = 0; s != 0; s /= 2, prec ++); 74 } 75 76 /* EXTREMUM needs prec bits, i.e. 2^(prec-1) <= |EXTREMUM| < 2^prec */ 77 78 /* if e <= prec - 1, then f < 2^(prec-1) <= |EXTREMUM| */ 79 if (e <= prec - 1) 80 return 1; 81 82 /* if e >= prec + 1, then f >= 2^prec > |EXTREMUM| */ 83 if (e >= prec + 1) 84 return 0; 85 86 MPFR_ASSERTD (e == prec); 87 88 /* hard case: first round to prec bits, then check */ 89 saved_flags = __gmpfr_flags; 90 mpfr_init2 (x, prec); 91 mpfr_set (x, f, rnd); 92 93 if (neg) 94 { 95 mpfr_init2 (y, prec); 96 mpfr_set_sj (y, MPFR_INTMAX_MIN, MPFR_RNDN); 97 res = mpfr_cmp (x, y) >= 0; 98 mpfr_clear (y); 99 } 100 else 101 { 102 /* Warning! Due to the rounding, x can be an infinity. Here we use 103 the fact that singular numbers have a special exponent field, 104 thus well-defined and different from e, in which case this means 105 that the number does not fit. That's why we use MPFR_EXP, not 106 MPFR_GET_EXP. */ 107 res = MPFR_EXP (x) == e; 108 } 109 110 mpfr_clear (x); 111 __gmpfr_flags = saved_flags; 112 return res; 113 } 114 115 #endif 116