get_si.c
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上传日期:2022-08-06
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- /* mpz_get_si(integer) -- Return the least significant digit from INTEGER.
- Copyright 1991, 1993, 1994, 1995, 2000, 2001, 2002, 2006 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"
- signed long int
- mpz_get_si (mpz_srcptr z)
- {
- mp_ptr zp = z->_mp_d;
- mp_size_t size = z->_mp_size;
- mp_limb_t zl = zp[0];
- #if GMP_NAIL_BITS != 0
- if (ULONG_MAX > GMP_NUMB_MAX && ABS (size) >= 2)
- zl |= zp[1] << GMP_NUMB_BITS;
- #endif
- if (size > 0)
- return (long) zl & LONG_MAX;
- else if (size < 0)
- /* This expression is necessary to properly handle 0x80000000 */
- return ~(((long) zl - 1L) & LONG_MAX);
- else
- return 0;
- }