aorsmul.c
上传用户:qaz666999
上传日期:2022-08-06
资源大小:2570k
文件大小:4k
- /* mpz_addmul, mpz_submul -- add or subtract multiple.
- Copyright 2001, 2004, 2005 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 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 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 Lesser General Public
- License for more details.
- You should have received a copy of the GNU Lesser General Public License
- along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
- #include "gmp.h"
- #include "gmp-impl.h"
- /* expecting x and y both with non-zero high limbs */
- #define mpn_cmp_twosizes_lt(xp,xsize, yp,ysize)
- ((xsize) < (ysize)
- || ((xsize) == (ysize) && mpn_cmp (xp, yp, xsize) < 0))
- /* sub>=0 means an addmul w += x*y, sub<0 means a submul w -= x*y.
- The signs of w, x and y are fully accounted for by each flipping "sub".
- The sign of w is retained for the result, unless the absolute value
- submul underflows, in which case it flips. */
- static void __gmpz_aorsmul __GMP_PROTO ((REGPARM_3_1 (mpz_ptr w, mpz_srcptr x, mpz_srcptr y, mp_size_t sub))) REGPARM_ATTR (1);
- #define mpz_aorsmul(w,x,y,sub) __gmpz_aorsmul (REGPARM_3_1 (w, x, y, sub))
- REGPARM_ATTR (1) static void
- mpz_aorsmul (mpz_ptr w, mpz_srcptr x, mpz_srcptr y, mp_size_t sub)
- {
- mp_size_t xsize, ysize, tsize, wsize, wsize_signed;
- mp_ptr wp, tp;
- mp_limb_t c, high;
- TMP_DECL;
- /* w unaffected if x==0 or y==0 */
- xsize = SIZ(x);
- ysize = SIZ(y);
- if (xsize == 0 || ysize == 0)
- return;
- /* make x the bigger of the two */
- if (ABS(ysize) > ABS(xsize))
- {
- MPZ_SRCPTR_SWAP (x, y);
- MP_SIZE_T_SWAP (xsize, ysize);
- }
- sub ^= ysize;
- ysize = ABS(ysize);
- /* use mpn_addmul_1/mpn_submul_1 if possible */
- if (ysize == 1)
- {
- mpz_aorsmul_1 (w, x, PTR(y)[0], sub);
- return;
- }
- sub ^= xsize;
- xsize = ABS(xsize);
- wsize_signed = SIZ(w);
- sub ^= wsize_signed;
- wsize = ABS(wsize_signed);
- tsize = xsize + ysize;
- MPZ_REALLOC (w, MAX (wsize, tsize) + 1);
- wp = PTR(w);
- if (wsize_signed == 0)
- {
- /* Nothing to add to, just set w=x*y. No w==x or w==y overlap here,
- since we know x,y!=0 but w==0. */
- high = mpn_mul (wp, PTR(x),xsize, PTR(y),ysize);
- tsize -= (high == 0);
- SIZ(w) = (sub >= 0 ? tsize : -tsize);
- return;
- }
- TMP_MARK;
- tp = TMP_ALLOC_LIMBS (tsize);
- high = mpn_mul (tp, PTR(x),xsize, PTR(y),ysize);
- tsize -= (high == 0);
- ASSERT (tp[tsize-1] != 0);
- if (sub >= 0)
- {
- mp_srcptr up = wp;
- mp_size_t usize = wsize;
- if (usize < tsize)
- {
- up = tp;
- usize = tsize;
- tp = wp;
- tsize = wsize;
- wsize = usize;
- }
- c = mpn_add (wp, up,usize, tp,tsize);
- wp[wsize] = c;
- wsize += (c != 0);
- }
- else
- {
- mp_srcptr up = wp;
- mp_size_t usize = wsize;
- if (mpn_cmp_twosizes_lt (up,usize, tp,tsize))
- {
- up = tp;
- usize = tsize;
- tp = wp;
- tsize = wsize;
- wsize = usize;
- wsize_signed = -wsize_signed;
- }
- ASSERT_NOCARRY (mpn_sub (wp, up,usize, tp,tsize));
- wsize = usize;
- MPN_NORMALIZE (wp, wsize);
- }
- SIZ(w) = (wsize_signed >= 0 ? wsize : -wsize);
- TMP_FREE;
- }
- void
- mpz_addmul (mpz_ptr w, mpz_srcptr u, mpz_srcptr v)
- {
- mpz_aorsmul (w, u, v, (mp_size_t) 0);
- }
- void
- mpz_submul (mpz_ptr w, mpz_srcptr u, mpz_srcptr v)
- {
- mpz_aorsmul (w, u, v, (mp_size_t) -1);
- }