1/* mpfr_mul_2si -- multiply a floating-point number by a power of two 2 3Copyright 1999, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc. 4Contributed by the Arenaire and Cacao 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#include "mpfr-impl.h" 24 25int 26mpfr_mul_2si (mpfr_ptr y, mpfr_srcptr x, long int n, mpfr_rnd_t rnd_mode) 27{ 28 int inexact; 29 30 MPFR_LOG_FUNC (("x[%#R]=%R n=%ld rnd=%d", x, x, n, rnd_mode), 31 ("y[%#R]=%R inexact=%d", y, y, inexact)); 32 33 if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x))) 34 return mpfr_set (y, x, rnd_mode); 35 else 36 { 37 mpfr_exp_t exp = MPFR_GET_EXP (x); 38 MPFR_SETRAW (inexact, y, x, exp, rnd_mode); 39 if (MPFR_UNLIKELY( n > 0 && (__gmpfr_emax < MPFR_EMIN_MIN + n || 40 exp > __gmpfr_emax - n))) 41 return mpfr_overflow (y, rnd_mode, MPFR_SIGN(y)); 42 else if (MPFR_UNLIKELY(n < 0 && (__gmpfr_emin > MPFR_EMAX_MAX + n || 43 exp < __gmpfr_emin - n))) 44 { 45 if (rnd_mode == MPFR_RNDN && 46 (__gmpfr_emin > MPFR_EMAX_MAX + (n + 1) || 47 exp < __gmpfr_emin - (n + 1) || 48 (inexact >= 0 && mpfr_powerof2_raw (y)))) 49 rnd_mode = MPFR_RNDZ; 50 return mpfr_underflow (y, rnd_mode, MPFR_SIGN(y)); 51 } 52 MPFR_SET_EXP (y, exp + n); 53 } 54 55 MPFR_RET (inexact); 56} 57