1 /* mpfr_fits_intmax_p -- test whether an mpfr fits an intmax_t. 2 3 Copyright 2004, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc. 4 Contributed by the AriC and Caramel 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 mpfr_exp_t e; 37 int prec; 38 mpfr_t x, y; 39 int neg; 40 int res; 41 42 if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (f))) 43 /* Zero always fit */ 44 return MPFR_IS_ZERO (f) ? 1 : 0; 45 46 /* now it fits if either 47 (a) MINIMUM <= f <= MAXIMUM 48 (b) or MINIMUM <= round(f, prec(slong), rnd) <= MAXIMUM */ 49 50 e = MPFR_EXP (f); 51 if (e < 1) 52 return 1; /* |f| < 1: always fits */ 53 54 neg = MPFR_IS_NEG (f); 55 56 /* let EXTREMUM be MAXIMUM if f > 0, and MINIMUM if f < 0 */ 57 58 /* first compute prec(EXTREMUM), this could be done at configure time, 59 but the result can depend on neg (the loop is moved inside the "if" 60 to give the compiler a better chance to compute prec statically) */ 61 if (neg) 62 { 63 uintmax_t s; 64 /* In C89, the division on negative integers isn't well-defined. */ 65 s = SAFE_ABS (uintmax_t, MPFR_INTMAX_MIN); 66 for (prec = 0; s != 0; s /= 2, prec ++); 67 } 68 else 69 { 70 intmax_t s; 71 s = MPFR_INTMAX_MAX; 72 for (prec = 0; s != 0; s /= 2, prec ++); 73 } 74 75 /* EXTREMUM needs prec bits, i.e. 2^(prec-1) <= |EXTREMUM| < 2^prec */ 76 77 /* if e <= prec - 1, then f < 2^(prec-1) <= |EXTREMUM| */ 78 if (e <= prec - 1) 79 return 1; 80 81 /* if e >= prec + 1, then f >= 2^prec > |EXTREMUM| */ 82 if (e >= prec + 1) 83 return 0; 84 85 MPFR_ASSERTD (e == prec); 86 87 /* hard case: first round to prec bits, then check */ 88 mpfr_init2 (x, prec); 89 mpfr_set (x, f, rnd); 90 91 if (neg) 92 { 93 mpfr_init2 (y, prec); 94 mpfr_set_sj (y, MPFR_INTMAX_MIN, MPFR_RNDN); 95 res = mpfr_cmp (x, y) >= 0; 96 mpfr_clear (y); 97 } 98 else 99 { 100 res = MPFR_GET_EXP (x) == e; 101 } 102 103 mpfr_clear (x); 104 return res; 105 } 106 107 #endif 108