From e7d21ee4f8ac907665a7e170c71d59e13a01da09 Mon Sep 17 00:00:00 2001 From: partain Date: Mon, 8 Jan 1996 20:28:12 +0000 Subject: [project @ 1996-01-08 20:28:12 by partain] Initial revision --- ghc/runtime/gmp/mpn_rshiftci.c | 86 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 86 insertions(+) create mode 100644 ghc/runtime/gmp/mpn_rshiftci.c (limited to 'ghc/runtime/gmp/mpn_rshiftci.c') diff --git a/ghc/runtime/gmp/mpn_rshiftci.c b/ghc/runtime/gmp/mpn_rshiftci.c new file mode 100644 index 0000000000..b072d02a90 --- /dev/null +++ b/ghc/runtime/gmp/mpn_rshiftci.c @@ -0,0 +1,86 @@ +/* mpn_rshiftci -- Shift a low level natural-number integer with carry in. + +Copyright (C) 1991 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 the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +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 a copy of the GNU General Public License +along with the GNU MP Library; see the file COPYING. If not, write to +the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ + +#include "gmp.h" +#include "gmp-impl.h" + +/* Shift U (pointed to by UP and USIZE digits long) CNT bits to the right + and store the USIZE least significant digits of the result at WP. + Return the size of the result. + + Argument constraints: + 0. U must be normalized (i.e. it's most significant digit != 0). + 1. 0 <= CNT < BITS_PER_MP_LIMB + 2. If the result is to be written over the input, WP must be <= UP. +*/ + +mp_size +#ifdef __STDC__ +mpn_rshiftci (mp_ptr wp, + mp_srcptr up, mp_size usize, + unsigned cnt, + mp_limb carry_in) +#else +mpn_rshiftci (wp, up, usize, cnt, carry_in) + mp_ptr wp; + mp_srcptr up; + mp_size usize; + unsigned cnt; + mp_limb carry_in; +#endif +{ + mp_limb high_limb, low_limb; + unsigned sh_1, sh_2; + mp_size i; + + if (usize <= 0) + return 0; + + sh_1 = cnt; + if (sh_1 == 0) + { + if (wp != up) + { + /* Copy from low end to high end, to allow specified input/output + overlapping. */ + for (i = 0; i < usize; i++) + wp[i] = up[i]; + } + return usize; + } + + wp -= 1; + sh_2 = BITS_PER_MP_LIMB - sh_1; + low_limb = up[0]; + for (i = 1; i < usize; i++) + { + high_limb = up[i]; + wp[i] = (low_limb >> sh_1) | (high_limb << sh_2); + low_limb = high_limb; + } + low_limb = (low_limb >> sh_1) | (carry_in << sh_2); + if (low_limb != 0) + { + wp[i] = low_limb; + return usize; + } + + return usize - 1; +} -- cgit v1.2.1