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Diffstat (limited to 'src/add.c')
-rw-r--r-- | src/add.c | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/src/add.c b/src/add.c new file mode 100644 index 000000000..08b56de9a --- /dev/null +++ b/src/add.c @@ -0,0 +1,107 @@ +/* mpfr_add -- add two floating-point numbers + +Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc. +Contributed by the Arenaire and Caramel projects, INRIA. + +This file is part of the GNU MPFR Library. + +The GNU MPFR Library is free software; you can redistribute it and/or modify +it under the terms of the GNU Lesser General Public License as published by +the Free Software Foundation; either version 3 of the License, or (at your +option) any later version. + +The GNU MPFR Library is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY +or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public +License for more details. + +You should have received a copy of the GNU Lesser General Public License +along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see +http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc., +51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */ + +#include "mpfr-impl.h" + +int +mpfr_add (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode) +{ + MPFR_LOG_FUNC (("b[%#R]=%R c[%#R]=%R rnd=%d", b, b, c, c, rnd_mode), + ("a[%#R]=%R", a, a)); + + if (MPFR_ARE_SINGULAR(b,c)) + { + if (MPFR_IS_NAN(b) || MPFR_IS_NAN(c)) + { + MPFR_SET_NAN(a); + MPFR_RET_NAN; + } + /* neither b nor c is NaN here */ + else if (MPFR_IS_INF(b)) + { + if (!MPFR_IS_INF(c) || MPFR_SIGN(b) == MPFR_SIGN(c)) + { + MPFR_SET_INF(a); + MPFR_SET_SAME_SIGN(a, b); + MPFR_RET(0); /* exact */ + } + else + { + MPFR_SET_NAN(a); + MPFR_RET_NAN; + } + } + else if (MPFR_IS_INF(c)) + { + MPFR_SET_INF(a); + MPFR_SET_SAME_SIGN(a, c); + MPFR_RET(0); /* exact */ + } + /* now either b or c is zero */ + else if (MPFR_IS_ZERO(b)) + { + if (MPFR_IS_ZERO(c)) + { + /* for round away, we take the same convention for 0 + 0 + as for round to zero or to nearest: it always gives +0, + except (-0) + (-0) = -0. */ + MPFR_SET_SIGN(a, + (rnd_mode != MPFR_RNDD ? + ((MPFR_IS_NEG(b) && MPFR_IS_NEG(c)) ? -1 : 1) : + ((MPFR_IS_POS(b) && MPFR_IS_POS(c)) ? 1 : -1))); + MPFR_SET_ZERO(a); + MPFR_RET(0); /* 0 + 0 is exact */ + } + return mpfr_set (a, c, rnd_mode); + } + else + { + MPFR_ASSERTD(MPFR_IS_ZERO(c)); + return mpfr_set (a, b, rnd_mode); + } + } + + MPFR_ASSERTD(MPFR_IS_PURE_FP(b) && MPFR_IS_PURE_FP(c)); + + if (MPFR_UNLIKELY(MPFR_SIGN(b) != MPFR_SIGN(c))) + { /* signs differ, it's a subtraction */ + if (MPFR_LIKELY(MPFR_PREC(a) == MPFR_PREC(b) + && MPFR_PREC(b) == MPFR_PREC(c))) + return mpfr_sub1sp(a,b,c,rnd_mode); + else + return mpfr_sub1(a, b, c, rnd_mode); + } + else + { /* signs are equal, it's an addition */ + if (MPFR_LIKELY(MPFR_PREC(a) == MPFR_PREC(b) + && MPFR_PREC(b) == MPFR_PREC(c))) + if (MPFR_GET_EXP(b) < MPFR_GET_EXP(c)) + return mpfr_add1sp(a, c, b, rnd_mode); + else + return mpfr_add1sp(a, b, c, rnd_mode); + else + if (MPFR_GET_EXP(b) < MPFR_GET_EXP(c)) + return mpfr_add1(a, c, b, rnd_mode); + else + return mpfr_add1(a, b, c, rnd_mode); + } +} |