set_d.c
上传用户:qaz666999
上传日期:2022-08-06
资源大小:2570k
文件大小:3k
- /* mpz_set_d(integer, val) -- Assign INTEGER with a double value VAL.
- Copyright 1995, 1996, 2000, 2001, 2002, 2003, 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 "config.h"
- #if HAVE_FLOAT_H
- #include <float.h> /* for DBL_MAX */
- #endif
- #include "gmp.h"
- #include "gmp-impl.h"
- /* We used to have a special case for d < MP_BASE_AS_DOUBLE, just casting
- double -> limb. Unfortunately gcc 3.3 on powerpc970-apple-darwin6.8.5
- got this wrong. (It assumed __fixunsdfdi returned its result in a single
- 64-bit register, where instead that function followed the calling
- conventions and gave the result in two parts r3 and r4.) Hence the use
- of __gmp_extract_double in all cases. */
- void
- mpz_set_d (mpz_ptr r, double d)
- {
- int negative;
- mp_limb_t tp[LIMBS_PER_DOUBLE];
- mp_ptr rp;
- mp_size_t rn;
- DOUBLE_NAN_INF_ACTION (d,
- __gmp_invalid_operation (),
- __gmp_invalid_operation ());
- negative = d < 0;
- d = ABS (d);
- rn = __gmp_extract_double (tp, d);
- if (ALLOC(r) < rn)
- _mpz_realloc (r, rn);
- if (rn <= 0)
- rn = 0;
- rp = PTR (r);
- switch (rn)
- {
- default:
- MPN_ZERO (rp, rn - LIMBS_PER_DOUBLE);
- rp += rn - LIMBS_PER_DOUBLE;
- /* fall through */
- #if LIMBS_PER_DOUBLE == 2
- case 2:
- rp[1] = tp[1], rp[0] = tp[0];
- break;
- case 1:
- rp[0] = tp[1];
- break;
- #endif
- #if LIMBS_PER_DOUBLE == 3
- case 3:
- rp[2] = tp[2], rp[1] = tp[1], rp[0] = tp[0];
- break;
- case 2:
- rp[1] = tp[2], rp[0] = tp[1];
- break;
- case 1:
- rp[0] = tp[2];
- break;
- #endif
- #if LIMBS_PER_DOUBLE == 4
- case 4:
- rp[3] = tp[3], rp[2] = tp[2], rp[1] = tp[1], rp[0] = tp[0];
- break;
- case 3:
- rp[2] = tp[3], rp[1] = tp[2], rp[0] = tp[1];
- break;
- case 2:
- rp[1] = tp[3], rp[0] = tp[2];
- break;
- case 1:
- rp[0] = tp[3];
- break;
- #endif
- case 0:
- break;
- }
- SIZ(r) = negative ? -rn : rn;
- }