1 /* mpfr_set_ui_2exp -- set a MPFR number from a machine unsigned integer with 2 a shift 3 4 Copyright 2004, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc. 5 Contributed by the Arenaire and Caramel projects, INRIA. 6 7 This file is part of the GNU MPFR Library. 8 9 The GNU MPFR Library is free software; you can redistribute it and/or modify 10 it under the terms of the GNU Lesser General Public License as published by 11 the Free Software Foundation; either version 3 of the License, or (at your 12 option) any later version. 13 14 The GNU MPFR Library is distributed in the hope that it will be useful, but 15 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 16 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 17 License for more details. 18 19 You should have received a copy of the GNU Lesser General Public License 20 along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see 21 http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc., 22 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */ 23 24 #define MPFR_NEED_LONGLONG_H 25 #include "mpfr-impl.h" 26 27 int 28 mpfr_set_ui_2exp (mpfr_ptr x, unsigned long i, mpfr_exp_t e, mpfr_rnd_t rnd_mode) 29 { 30 MPFR_SET_POS (x); 31 32 if (i == 0) 33 { 34 MPFR_SET_ZERO (x); 35 MPFR_RET (0); 36 } 37 else 38 { 39 mp_size_t xn; 40 unsigned int cnt, nbits; 41 mp_limb_t *xp; 42 int inex = 0; 43 44 /* FIXME: support int limbs (e.g. 16-bit limbs on 16-bit proc) */ 45 MPFR_ASSERTD (i == (mp_limb_t) i); 46 47 /* Position of the highest limb */ 48 xn = (MPFR_PREC (x) - 1) / GMP_NUMB_BITS; 49 count_leading_zeros (cnt, (mp_limb_t) i); 50 MPFR_ASSERTD (cnt < GMP_NUMB_BITS); /* OK since i != 0 */ 51 52 xp = MPFR_MANT(x); 53 xp[xn] = ((mp_limb_t) i) << cnt; 54 /* Zero the xn lower limbs. */ 55 MPN_ZERO(xp, xn); 56 57 nbits = GMP_NUMB_BITS - cnt; 58 e += nbits; /* exponent _before_ the rounding */ 59 60 /* round if MPFR_PREC(x) smaller than length of i */ 61 if (MPFR_UNLIKELY (MPFR_PREC (x) < nbits) && 62 MPFR_UNLIKELY (mpfr_round_raw (xp + xn, xp + xn, nbits, 0, 63 MPFR_PREC (x), rnd_mode, &inex))) 64 { 65 e++; 66 xp[xn] = MPFR_LIMB_HIGHBIT; 67 } 68 69 MPFR_EXP (x) = e; 70 return mpfr_check_range (x, inex, rnd_mode); 71 } 72 } 73