mul.c
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上传日期:2022-08-06
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文件大小:2k
- /* mpf_mul -- Multiply two floats.
- Copyright 1993, 1994, 1996, 2001, 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"
- void
- mpf_mul (mpf_ptr r, mpf_srcptr u, mpf_srcptr v)
- {
- mp_srcptr up, vp;
- mp_size_t usize, vsize;
- mp_size_t sign_product;
- mp_size_t prec = r->_mp_prec;
- TMP_DECL;
- TMP_MARK;
- usize = u->_mp_size;
- vsize = v->_mp_size;
- sign_product = usize ^ vsize;
- usize = ABS (usize);
- vsize = ABS (vsize);
- up = u->_mp_d;
- vp = v->_mp_d;
- if (usize > prec)
- {
- up += usize - prec;
- usize = prec;
- }
- if (vsize > prec)
- {
- vp += vsize - prec;
- vsize = prec;
- }
- if (usize == 0 || vsize == 0)
- {
- r->_mp_size = 0;
- r->_mp_exp = 0; /* ??? */
- }
- else
- {
- mp_size_t rsize;
- mp_limb_t cy_limb;
- mp_ptr rp, tp;
- mp_size_t adj;
- rsize = usize + vsize;
- tp = TMP_ALLOC_LIMBS (rsize);
- cy_limb = (usize >= vsize
- ? mpn_mul (tp, up, usize, vp, vsize)
- : mpn_mul (tp, vp, vsize, up, usize));
- adj = cy_limb == 0;
- rsize -= adj;
- prec++;
- if (rsize > prec)
- {
- tp += rsize - prec;
- rsize = prec;
- }
- rp = r->_mp_d;
- MPN_COPY (rp, tp, rsize);
- r->_mp_exp = u->_mp_exp + v->_mp_exp - adj;
- r->_mp_size = sign_product >= 0 ? rsize : -rsize;
- }
- TMP_FREE;
- }