1/* mpfr_get_sj -- convert a MPFR number to a huge machine signed integer 2 3Copyright 2004, 2006-2023 Free Software Foundation, Inc. 4Contributed by the AriC and Caramba projects, INRIA. 5 6This file is part of the GNU MPFR Library. 7 8The GNU MPFR Library is free software; you can redistribute it and/or modify 9it under the terms of the GNU Lesser General Public License as published by 10the Free Software Foundation; either version 3 of the License, or (at your 11option) any later version. 12 13The GNU MPFR Library is distributed in the hope that it will be useful, but 14WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 15or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 16License for more details. 17 18You should have received a copy of the GNU Lesser General Public License 19along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see 20https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc., 2151 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */ 22 23#define MPFR_NEED_INTMAX_H 24#include "mpfr-impl.h" 25 26#ifdef _MPFR_H_HAVE_INTMAX_T 27 28intmax_t 29mpfr_get_sj (mpfr_srcptr f, mpfr_rnd_t rnd) 30{ 31 intmax_t r; 32 mpfr_prec_t prec; 33 mpfr_t x; 34 MPFR_SAVE_EXPO_DECL (expo); 35 36 if (MPFR_UNLIKELY (!mpfr_fits_intmax_p (f, rnd))) 37 { 38 MPFR_SET_ERANGEFLAG (); 39 return MPFR_IS_NAN (f) ? 0 : 40 MPFR_IS_NEG (f) ? INTMAX_MIN : INTMAX_MAX; 41 } 42 43 if (MPFR_IS_ZERO (f)) 44 return (intmax_t) 0; 45 46 /* Determine the precision of intmax_t. |INTMAX_MIN| may have one 47 more bit as an integer, but in this case, this is a power of 2, 48 thus fits in a precision-prec floating-point number. */ 49 for (r = INTMAX_MAX, prec = 0; r != 0; r /= 2, prec++) 50 { } 51 52 MPFR_ASSERTD (r == 0); 53 54 MPFR_SAVE_EXPO_MARK (expo); 55 56 mpfr_init2 (x, prec); 57 mpfr_rint (x, f, rnd); 58 MPFR_ASSERTN (MPFR_IS_FP (x)); 59 60 /* The flags from mpfr_rint are the wanted ones. In particular, 61 it sets the inexact flag when necessary. */ 62 MPFR_SAVE_EXPO_UPDATE_FLAGS (expo, __gmpfr_flags); 63 64 if (MPFR_NOTZERO (x)) 65 { 66 mp_limb_t *xp; 67 int sh; /* An int should be sufficient in this context. */ 68 69 xp = MPFR_MANT (x); 70 sh = MPFR_GET_EXP (x); 71 MPFR_ASSERTN ((mpfr_prec_t) sh <= prec + 1); 72 if (INTMAX_MIN + INTMAX_MAX != 0 73 && MPFR_UNLIKELY ((mpfr_prec_t) sh > prec)) 74 { 75 /* 2's complement and x <= INTMAX_MIN: in the case mp_limb_t 76 has the same size as intmax_t, we cannot use the code in 77 the for loop since the operations would be performed in 78 unsigned arithmetic. */ 79 MPFR_ASSERTD (MPFR_IS_NEG (x) && mpfr_powerof2_raw (x)); 80 r = INTMAX_MIN; 81 } 82 /* sh is the number of bits that remain to be considered in {xp, xn} */ 83 else 84 { 85#ifdef MPFR_INTMAX_WITHIN_LIMB 86 MPFR_ASSERTD (sh > 0 && sh < GMP_NUMB_BITS); 87 r = xp[0] >> (GMP_NUMB_BITS - sh); 88#else 89 int n; 90 91 /* Note: testing the condition sh > 0 is necessary to avoid 92 an undefined behavior on xp[n] >> S when S >= GMP_NUMB_BITS 93 (even though xp[n] == 0 in such a case). This can happen if 94 sizeof(mp_limb_t) < sizeof(intmax_t) and |x| is small enough 95 because of the trailing bits due to its normalization. */ 96 for (n = MPFR_LIMB_SIZE (x) - 1; n >= 0 && sh > 0; n--) 97 { 98 sh -= GMP_NUMB_BITS; 99 /* Note the concerning the casts below: 100 When sh >= 0, the cast must be performed before the shift 101 for the case sizeof(intmax_t) > sizeof(mp_limb_t). 102 When sh < 0, the cast must be performed after the shift 103 for the case sizeof(intmax_t) == sizeof(mp_limb_t), as 104 mp_limb_t is unsigned, therefore not representable as an 105 intmax_t when the MSB is 1 (this is the case here). */ 106 MPFR_ASSERTD (-sh < GMP_NUMB_BITS); 107 /* each limb should be shifted by sh bits to the left if sh>=0, 108 and by sh bits to the right if sh < 0 */ 109 r += sh >= 0 110 ? (intmax_t) xp[n] << sh 111 : (intmax_t) (xp[n] >> (-sh)); 112 } 113#endif 114 if (MPFR_IS_NEG(x)) 115 r = -r; 116 } 117 } 118 119 mpfr_clear (x); 120 121 MPFR_SAVE_EXPO_FREE (expo); 122 123 return r; 124} 125 126#endif 127