Annotation of OpenXM/src/kan96xx/gmp-2.0.2/mpz/tdiv_r_2exp.c, Revision 1.1
1.1 ! maekawa 1: /* mpz_tdiv_r_2exp -- Divide a integer by 2**CNT and produce a remainder.
! 2:
! 3: Copyright (C) 1991, 1993, 1994, 1995 Free Software Foundation, Inc.
! 4:
! 5: This file is part of the GNU MP Library.
! 6:
! 7: The GNU MP Library is free software; you can redistribute it and/or modify
! 8: it under the terms of the GNU Library General Public License as published by
! 9: the Free Software Foundation; either version 2 of the License, or (at your
! 10: option) any later version.
! 11:
! 12: The GNU MP Library is distributed in the hope that it will be useful, but
! 13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
! 14: or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
! 15: License for more details.
! 16:
! 17: You should have received a copy of the GNU Library General Public License
! 18: along with the GNU MP Library; see the file COPYING.LIB. If not, write to
! 19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
! 20: MA 02111-1307, USA. */
! 21:
! 22: #include "gmp.h"
! 23: #include "gmp-impl.h"
! 24:
! 25: void
! 26: #if __STDC__
! 27: mpz_tdiv_r_2exp (mpz_ptr res, mpz_srcptr in, unsigned long int cnt)
! 28: #else
! 29: mpz_tdiv_r_2exp (res, in, cnt)
! 30: mpz_ptr res;
! 31: mpz_srcptr in;
! 32: unsigned long int cnt;
! 33: #endif
! 34: {
! 35: mp_size_t in_size = ABS (in->_mp_size);
! 36: mp_size_t res_size;
! 37: mp_size_t limb_cnt = cnt / BITS_PER_MP_LIMB;
! 38: mp_srcptr in_ptr = in->_mp_d;
! 39:
! 40: if (in_size > limb_cnt)
! 41: {
! 42: /* The input operand is (probably) greater than 2**CNT. */
! 43: mp_limb_t x;
! 44:
! 45: x = in_ptr[limb_cnt] & (((mp_limb_t) 1 << cnt % BITS_PER_MP_LIMB) - 1);
! 46: if (x != 0)
! 47: {
! 48: res_size = limb_cnt + 1;
! 49: if (res->_mp_alloc < res_size)
! 50: _mpz_realloc (res, res_size);
! 51:
! 52: res->_mp_d[limb_cnt] = x;
! 53: }
! 54: else
! 55: {
! 56: res_size = limb_cnt;
! 57: MPN_NORMALIZE (in_ptr, res_size);
! 58:
! 59: if (res->_mp_alloc < res_size)
! 60: _mpz_realloc (res, res_size);
! 61:
! 62: limb_cnt = res_size;
! 63: }
! 64: }
! 65: else
! 66: {
! 67: /* The input operand is smaller than 2**CNT. We perform a no-op,
! 68: apart from that we might need to copy IN to RES. */
! 69: res_size = in_size;
! 70: if (res->_mp_alloc < res_size)
! 71: _mpz_realloc (res, res_size);
! 72:
! 73: limb_cnt = res_size;
! 74: }
! 75:
! 76: if (res != in)
! 77: MPN_COPY (res->_mp_d, in->_mp_d, limb_cnt);
! 78: res->_mp_size = in->_mp_size >= 0 ? res_size : -res_size;
! 79: }
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