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Diffstat (limited to 'Build/source/libs/mpfr/mpfr-src/src/div_2ui.c')
-rw-r--r-- | Build/source/libs/mpfr/mpfr-src/src/div_2ui.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/Build/source/libs/mpfr/mpfr-src/src/div_2ui.c b/Build/source/libs/mpfr/mpfr-src/src/div_2ui.c new file mode 100644 index 00000000000..349d8367af3 --- /dev/null +++ b/Build/source/libs/mpfr/mpfr-src/src/div_2ui.c @@ -0,0 +1,69 @@ +/* mpfr_div_2ui -- divide a floating-point number by a power of two + +Copyright 1999, 2001-2020 Free Software Foundation, Inc. +Contributed by the AriC and Caramba 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 +https://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_div_2ui (mpfr_ptr y, mpfr_srcptr x, unsigned long n, mpfr_rnd_t rnd_mode) +{ + int inexact; + + MPFR_LOG_FUNC ( + ("x[%Pu]=%.*Rg n=%lu rnd=%d", mpfr_get_prec(x), mpfr_log_prec, x, n, + rnd_mode), + ("y[%Pu]=%.*Rg inexact=%d", mpfr_get_prec(y), mpfr_log_prec, y, inexact)); + + if (MPFR_UNLIKELY (n == 0 || MPFR_IS_SINGULAR (x))) + return mpfr_set (y, x, rnd_mode); + else + { + mpfr_exp_t exp = MPFR_GET_EXP (x); + mpfr_uexp_t diffexp; + + MPFR_SETRAW (inexact, y, x, exp, rnd_mode); + /* Warning! exp may have increased by 1 due to rounding. Thus the + difference below may overflow in a mpfr_exp_t; but mpfr_uexp_t + is OK to hold the value, with the difference done in unsigned + integer arithmetic in this type. */ + diffexp = (mpfr_uexp_t) exp - (mpfr_uexp_t) (__gmpfr_emin - 1); + if (MPFR_UNLIKELY (n >= diffexp)) /* exp - n <= emin - 1 */ + { + if (rnd_mode == MPFR_RNDN && + (n > diffexp || + ((MPFR_IS_NEG (y) ? inexact <= 0 : inexact >= 0) && + mpfr_powerof2_raw (y)))) + rnd_mode = MPFR_RNDZ; + return mpfr_underflow (y, rnd_mode, MPFR_SIGN (y)); + } + /* Now, n < diffexp, i.e. n <= exp - emin, which a difference of + * two valid exponents + 0 or 1, thus fits in a mpfr_exp_t (from + * the constraints on valid exponents). Moreover, there cannot be + * an overflow (if exp had been increased by 1 due to rounding) + * since the case n = 0 has been filtered out. + */ + MPFR_ASSERTD (n <= MPFR_EXP_MAX); + MPFR_ASSERTD (n >= 1); + MPFR_SET_EXP (y, exp - (mpfr_exp_t) n); + } + + MPFR_RET (inexact); +} |