summaryrefslogtreecommitdiff
path: root/Build/source/libs/mpfr/mpfr-src/src/div_2ui.c
diff options
context:
space:
mode:
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.c69
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);
+}