1/* mpfr_set_f -- set a MPFR number from a GNU MPF number 2 3Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc. 4Contributed by the AriC and Caramel 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 20http://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_LONGLONG_H 24#include "mpfr-impl.h" 25 26int 27mpfr_set_f (mpfr_ptr y, mpf_srcptr x, mpfr_rnd_t rnd_mode) 28{ 29 mp_limb_t *my, *mx, *tmp; 30 unsigned long cnt, sx, sy; 31 int inexact, carry = 0; 32 MPFR_TMP_DECL(marker); 33 34 sx = ABS(SIZ(x)); /* number of limbs of the mantissa of x */ 35 36 if (sx == 0) /* x is zero */ 37 { 38 MPFR_SET_ZERO(y); 39 MPFR_SET_POS(y); 40 return 0; /* 0 is exact */ 41 } 42 43 if (SIZ(x) * MPFR_FROM_SIGN_TO_INT(MPFR_SIGN(y)) < 0) 44 MPFR_CHANGE_SIGN (y); 45 46 sy = MPFR_LIMB_SIZE (y); 47 my = MPFR_MANT(y); 48 mx = PTR(x); 49 50 count_leading_zeros(cnt, mx[sx - 1]); 51 52 if (sy <= sx) /* we may have to round even when sy = sx */ 53 { 54 unsigned long xprec = sx * GMP_NUMB_BITS; 55 56 MPFR_TMP_MARK(marker); 57 tmp = MPFR_TMP_LIMBS_ALLOC (sx); 58 if (cnt) 59 mpn_lshift (tmp, mx, sx, cnt); 60 else 61 /* FIXME: we may avoid the copy here, and directly call mpfr_round_raw 62 on mx instead of tmp */ 63 MPN_COPY (tmp, mx, sx); 64 carry = mpfr_round_raw (my, tmp, xprec, (SIZ(x) < 0), MPFR_PREC(y), 65 rnd_mode, &inexact); 66 if (MPFR_UNLIKELY(carry)) /* result is a power of two */ 67 my[sy - 1] = MPFR_LIMB_HIGHBIT; 68 MPFR_TMP_FREE(marker); 69 } 70 else 71 { 72 if (cnt) 73 mpn_lshift (my + sy - sx, mx, sx, cnt); 74 else 75 MPN_COPY (my + sy - sx, mx, sx); 76 MPN_ZERO(my, sy - sx); 77 /* no rounding necessary, since y has a larger mantissa */ 78 inexact = 0; 79 } 80 81 /* warning: EXP(x) * GMP_NUMB_BITS may exceed the maximal exponent */ 82 if (EXP(x) > 1 + (__gmpfr_emax - 1) / GMP_NUMB_BITS) 83 { 84 /* EXP(x) >= 2 + floor((__gmpfr_emax-1)/GMP_NUMB_BITS) 85 EXP(x) >= 2 + (__gmpfr_emax - GMP_NUMB_BITS) / GMP_NUMB_BITS 86 >= 1 + __gmpfr_emax / GMP_NUMB_BITS 87 EXP(x) * GMP_NUMB_BITS >= __gmpfr_emax + GMP_NUMB_BITS 88 Since 0 <= cnt <= GMP_NUMB_BITS-1, and 0 <= carry <= 1, 89 we have then EXP(x) * GMP_NUMB_BITS - cnt + carry > __gmpfr_emax */ 90 return mpfr_overflow (y, rnd_mode, MPFR_SIGN (y)); 91 } 92 else 93 { 94 /* Do not use MPFR_SET_EXP as the exponent may be out of range. */ 95 MPFR_EXP (y) = EXP (x) * GMP_NUMB_BITS - (mpfr_exp_t) cnt + carry; 96 } 97 98 return mpfr_check_range (y, inexact, rnd_mode); 99} 100