trunc.c
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上传日期:2022-08-06
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- /* mpf_trunc -- truncate an mpf to an integer.
- Copyright 2001 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"
- /* Notice the use of prec+1 ensures mpf_trunc is equivalent to mpf_set if u
- is already an integer. */
- void
- mpf_trunc (mpf_ptr r, mpf_srcptr u)
- {
- mp_ptr rp;
- mp_srcptr up;
- mp_size_t size, asize, prec;
- mp_exp_t exp;
- exp = EXP(u);
- size = SIZ(u);
- if (size == 0 || exp <= 0)
- {
- /* u is only a fraction */
- SIZ(r) = 0;
- EXP(r) = 0;
- return;
- }
- up = PTR(u);
- EXP(r) = exp;
- asize = ABS (size);
- up += asize;
- /* skip fraction part of u */
- asize = MIN (asize, exp);
- /* don't lose precision in the copy */
- prec = PREC(r) + 1;
- /* skip excess over target precision */
- asize = MIN (asize, prec);
- up -= asize;
- rp = PTR(r);
- SIZ(r) = (size >= 0 ? asize : -asize);
- if (rp != up)
- MPN_COPY_INCR (rp, up, asize);
- }