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Diffstat (limited to 'Build/source/libs/gmp/gmp-src/mpn/generic/rshift.c')
-rw-r--r-- | Build/source/libs/gmp/gmp-src/mpn/generic/rshift.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/Build/source/libs/gmp/gmp-src/mpn/generic/rshift.c b/Build/source/libs/gmp/gmp-src/mpn/generic/rshift.c new file mode 100644 index 00000000000..15d427ddc15 --- /dev/null +++ b/Build/source/libs/gmp/gmp-src/mpn/generic/rshift.c @@ -0,0 +1,69 @@ +/* mpn_rshift -- Shift right low level. + +Copyright 1991, 1993, 1994, 1996, 2000-2002 Free Software Foundation, Inc. + +This file is part of the GNU MP Library. + +The GNU MP Library is free software; you can redistribute it and/or modify +it under the terms of either: + + * 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. + +or + + * the GNU General Public License as published by the Free Software + Foundation; either version 2 of the License, or (at your option) any + later version. + +or both in parallel, as here. + +The GNU MP 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 General Public License +for more details. + +You should have received copies of the GNU General Public License and the +GNU Lesser General Public License along with the GNU MP Library. If not, +see https://www.gnu.org/licenses/. */ + +#include "gmp-impl.h" + +/* Shift U (pointed to by up and N limbs long) cnt bits to the right + and store the n least significant limbs of the result at rp. + The bits shifted out to the right are returned. + + Argument constraints: + 1. 0 < cnt < GMP_NUMB_BITS. + 2. If the result is to be written over the input, rp must be <= up. +*/ + +mp_limb_t +mpn_rshift (mp_ptr rp, mp_srcptr up, mp_size_t n, unsigned int cnt) +{ + mp_limb_t high_limb, low_limb; + unsigned int tnc; + mp_size_t i; + mp_limb_t retval; + + ASSERT (n >= 1); + ASSERT (cnt >= 1); + ASSERT (cnt < GMP_NUMB_BITS); + ASSERT (MPN_SAME_OR_INCR_P (rp, up, n)); + + tnc = GMP_NUMB_BITS - cnt; + high_limb = *up++; + retval = (high_limb << tnc) & GMP_NUMB_MASK; + low_limb = high_limb >> cnt; + + for (i = n - 1; i != 0; i--) + { + high_limb = *up++; + *rp++ = low_limb | ((high_limb << tnc) & GMP_NUMB_MASK); + low_limb = high_limb >> cnt; + } + *rp = low_limb; + + return retval; +} |