1/* mpfr_add -- add two floating-point numbers 2 3Copyright 1999, 2000, 2001, 2002, 2003, 2004, 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#include "mpfr-impl.h" 24 25int 26mpfr_add (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode) 27{ 28 MPFR_LOG_FUNC 29 (("b[%Pu]=%.*Rg c[%Pu]=%.*Rg rnd=%d", 30 mpfr_get_prec (b), mpfr_log_prec, b, 31 mpfr_get_prec (c), mpfr_log_prec, c, rnd_mode), 32 ("a[%Pu]=%.*Rg", mpfr_get_prec (a), mpfr_log_prec, a)); 33 34 if (MPFR_ARE_SINGULAR(b,c)) 35 { 36 if (MPFR_IS_NAN(b) || MPFR_IS_NAN(c)) 37 { 38 MPFR_SET_NAN(a); 39 MPFR_RET_NAN; 40 } 41 /* neither b nor c is NaN here */ 42 else if (MPFR_IS_INF(b)) 43 { 44 if (!MPFR_IS_INF(c) || MPFR_SIGN(b) == MPFR_SIGN(c)) 45 { 46 MPFR_SET_INF(a); 47 MPFR_SET_SAME_SIGN(a, b); 48 MPFR_RET(0); /* exact */ 49 } 50 else 51 { 52 MPFR_SET_NAN(a); 53 MPFR_RET_NAN; 54 } 55 } 56 else if (MPFR_IS_INF(c)) 57 { 58 MPFR_SET_INF(a); 59 MPFR_SET_SAME_SIGN(a, c); 60 MPFR_RET(0); /* exact */ 61 } 62 /* now either b or c is zero */ 63 else if (MPFR_IS_ZERO(b)) 64 { 65 if (MPFR_IS_ZERO(c)) 66 { 67 /* for round away, we take the same convention for 0 + 0 68 as for round to zero or to nearest: it always gives +0, 69 except (-0) + (-0) = -0. */ 70 MPFR_SET_SIGN(a, 71 (rnd_mode != MPFR_RNDD ? 72 ((MPFR_IS_NEG(b) && MPFR_IS_NEG(c)) ? -1 : 1) : 73 ((MPFR_IS_POS(b) && MPFR_IS_POS(c)) ? 1 : -1))); 74 MPFR_SET_ZERO(a); 75 MPFR_RET(0); /* 0 + 0 is exact */ 76 } 77 return mpfr_set (a, c, rnd_mode); 78 } 79 else 80 { 81 MPFR_ASSERTD(MPFR_IS_ZERO(c)); 82 return mpfr_set (a, b, rnd_mode); 83 } 84 } 85 86 MPFR_ASSERTD (MPFR_IS_PURE_FP (b)); 87 MPFR_ASSERTD (MPFR_IS_PURE_FP (c)); 88 89 if (MPFR_UNLIKELY(MPFR_SIGN(b) != MPFR_SIGN(c))) 90 { /* signs differ, it is a subtraction */ 91 if (MPFR_LIKELY(MPFR_PREC(a) == MPFR_PREC(b) 92 && MPFR_PREC(b) == MPFR_PREC(c))) 93 return mpfr_sub1sp(a, b, c, rnd_mode); 94 else 95 return mpfr_sub1(a, b, c, rnd_mode); 96 } 97 else 98 { /* signs are equal, it's an addition */ 99 if (MPFR_LIKELY(MPFR_PREC(a) == MPFR_PREC(b) 100 && MPFR_PREC(b) == MPFR_PREC(c))) 101 if (MPFR_GET_EXP(b) < MPFR_GET_EXP(c)) 102 return mpfr_add1sp(a, c, b, rnd_mode); 103 else 104 return mpfr_add1sp(a, b, c, rnd_mode); 105 else 106 if (MPFR_GET_EXP(b) < MPFR_GET_EXP(c)) 107 return mpfr_add1(a, c, b, rnd_mode); 108 else 109 return mpfr_add1(a, b, c, rnd_mode); 110 } 111} 112