set_f.c
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上传日期:2022-08-06
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- /* mpz_set_f (dest_integer, src_float) -- Assign DEST_INTEGER from SRC_FLOAT.
- Copyright 1996, 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"
- void
- mpz_set_f (mpz_ptr w, mpf_srcptr u)
- {
- mp_ptr wp, up;
- mp_size_t size;
- mp_exp_t exp;
- /* abs(u)<1 truncates to zero */
- exp = EXP (u);
- if (exp <= 0)
- {
- SIZ(w) = 0;
- return;
- }
- MPZ_REALLOC (w, exp);
- wp = PTR(w);
- up = PTR(u);
- size = SIZ (u);
- SIZ(w) = (size >= 0 ? exp : -exp);
- size = ABS (size);
- if (exp > size)
- {
- /* pad with low zeros to get a total "exp" many limbs */
- mp_size_t zeros = exp - size;
- MPN_ZERO (wp, zeros);
- wp += zeros;
- }
- else
- {
- /* exp<=size, trucate to the high "exp" many limbs */
- up += (size - exp);
- size = exp;
- }
- MPN_COPY (wp, up, size);
- }