set_d.c
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上传日期:2022-08-06
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- /* mpq_set_d(mpq_t q, double d) -- Set q to d without rounding.
- Copyright 2000, 2002, 2003 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"
- #include "longlong.h"
- #if LIMBS_PER_DOUBLE > 4
- choke me
- #endif
- void
- mpq_set_d (mpq_ptr dest, double d)
- {
- int negative;
- mp_exp_t exp;
- mp_limb_t tp[LIMBS_PER_DOUBLE];
- mp_ptr np, dp;
- mp_size_t nn, dn;
- int c;
- DOUBLE_NAN_INF_ACTION (d,
- __gmp_invalid_operation (),
- __gmp_invalid_operation ());
- negative = d < 0;
- d = ABS (d);
- exp = __gmp_extract_double (tp, d);
- /* There are two main version of the conversion. The `then' arm handles
- numbers with a fractional part, while the `else' arm handles integers. */
- #if LIMBS_PER_DOUBLE == 4
- if (exp <= 1 || (exp == 2 && (tp[0] | tp[1]) != 0))
- #endif
- #if LIMBS_PER_DOUBLE == 3
- if (exp <= 1 || (exp == 2 && tp[0] != 0))
- #endif
- #if LIMBS_PER_DOUBLE == 2
- if (exp <= 1)
- #endif
- {
- if (d == 0.0)
- {
- SIZ(&(dest->_mp_num)) = 0;
- SIZ(&(dest->_mp_den)) = 1;
- PTR(&(dest->_mp_den))[0] = 1;
- return;
- }
- dn = -exp;
- MPZ_REALLOC (&(dest->_mp_num), 3);
- np = PTR(&(dest->_mp_num));
- #if LIMBS_PER_DOUBLE == 4
- if ((tp[0] | tp[1] | tp[2]) == 0)
- np[0] = tp[3], nn = 1;
- else if ((tp[0] | tp[1]) == 0)
- np[1] = tp[3], np[0] = tp[2], nn = 2;
- else if (tp[0] == 0)
- np[2] = tp[3], np[1] = tp[2], np[0] = tp[1], nn = 3;
- else
- np[3] = tp[3], np[2] = tp[2], np[1] = tp[1], np[0] = tp[0], nn = 4;
- #endif
- #if LIMBS_PER_DOUBLE == 3
- if ((tp[0] | tp[1]) == 0)
- np[0] = tp[2], nn = 1;
- else if (tp[0] == 0)
- np[1] = tp[2], np[0] = tp[1], nn = 2;
- else
- np[2] = tp[2], np[1] = tp[1], np[0] = tp[0], nn = 3;
- #endif
- #if LIMBS_PER_DOUBLE == 2
- if (tp[0] == 0)
- np[0] = tp[1], nn = 1;
- else
- np[1] = tp[1], np[0] = tp[0], nn = 2;
- #endif
- dn += nn + 1;
- ASSERT_ALWAYS (dn > 0);
- MPZ_REALLOC (&(dest->_mp_den), dn);
- dp = PTR(&(dest->_mp_den));
- MPN_ZERO (dp, dn - 1);
- dp[dn - 1] = 1;
- count_trailing_zeros (c, np[0] | dp[0]);
- if (c != 0)
- {
- mpn_rshift (np, np, nn, c);
- nn -= np[nn - 1] == 0;
- mpn_rshift (dp, dp, dn, c);
- dn -= dp[dn - 1] == 0;
- }
- SIZ(&(dest->_mp_den)) = dn;
- SIZ(&(dest->_mp_num)) = negative ? -nn : nn;
- }
- else
- {
- nn = exp;
- MPZ_REALLOC (&(dest->_mp_num), nn);
- np = PTR(&(dest->_mp_num));
- switch (nn)
- {
- default:
- MPN_ZERO (np, nn - LIMBS_PER_DOUBLE);
- np += nn - LIMBS_PER_DOUBLE;
- /* fall through */
- #if LIMBS_PER_DOUBLE == 2
- case 2:
- np[1] = tp[1], np[0] = tp[0];
- break;
- #endif
- #if LIMBS_PER_DOUBLE == 3
- case 3:
- np[2] = tp[2], np[1] = tp[1], np[0] = tp[0];
- break;
- case 2:
- np[1] = tp[2], np[0] = tp[1];
- break;
- #endif
- #if LIMBS_PER_DOUBLE == 4
- case 4:
- np[3] = tp[3], np[2] = tp[2], np[1] = tp[1], np[0] = tp[0];
- break;
- case 3:
- np[2] = tp[3], np[1] = tp[2], np[0] = tp[1];
- break;
- case 2:
- np[1] = tp[3], np[0] = tp[2];
- break;
- #endif
- }
- dp = PTR(&(dest->_mp_den));
- dp[0] = 1;
- SIZ(&(dest->_mp_den)) = 1;
- SIZ(&(dest->_mp_num)) = negative ? -nn : nn;
- }
- }