Annotation of OpenXM_contrib/gmp/mpz/get_d.c, Revision 1.1.1.3
1.1 maekawa 1: /* double mpz_get_d (mpz_t src) -- Return the double approximation to SRC.
2:
1.1.1.3 ! ohara 3: Copyright 1996, 1997, 2000, 2001, 2002 Free Software Foundation, Inc.
1.1 maekawa 4:
5: This file is part of the GNU MP Library.
6:
7: The GNU MP Library is free software; you can redistribute it and/or modify
1.1.1.2 maekawa 8: it under the terms of the GNU Lesser General Public License as published by
9: the Free Software Foundation; either version 2.1 of the License, or (at your
1.1 maekawa 10: option) any later version.
11:
12: The GNU MP Library is distributed in the hope that it will be useful, but
13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
1.1.1.2 maekawa 14: or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
1.1 maekawa 15: License for more details.
16:
1.1.1.2 maekawa 17: You should have received a copy of the GNU Lesser General Public License
1.1 maekawa 18: along with the GNU MP Library; see the file COPYING.LIB. If not, write to
19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
20: MA 02111-1307, USA. */
21:
22: #include "gmp.h"
23: #include "gmp-impl.h"
1.1.1.2 maekawa 24: #include "longlong.h"
25:
26:
1.1.1.3 ! ohara 27: /* FIXME: Would prefer to inline this on all compilers, not just those with
! 28: "inline". */
! 29: static inline int
! 30: mpn_zero_p (mp_srcptr p, mp_size_t n)
1.1.1.2 maekawa 31: {
32: mp_size_t i;
33:
34: for (i = 0; i < n; i++)
1.1.1.3 ! ohara 35: if (p[i] != 0)
! 36: return 0;
1.1.1.2 maekawa 37:
38: return 1;
39: }
40:
1.1 maekawa 41:
42: double
43: mpz_get_d (mpz_srcptr src)
44: {
45: double res;
1.1.1.2 maekawa 46: mp_size_t size;
1.1 maekawa 47: int negative;
48: mp_ptr qp;
1.1.1.2 maekawa 49: mp_limb_t hz, lz;
50: int cnt;
1.1 maekawa 51:
52: size = SIZ(src);
53: if (size == 0)
54: return 0.0;
55:
56: negative = size < 0;
57: size = ABS (size);
58: qp = PTR(src);
59:
1.1.1.2 maekawa 60: if (size == 1)
61: {
62: res = qp[size - 1];
63: }
64: else if (size == 2)
65: {
66: res = MP_BASE_AS_DOUBLE * qp[size - 1] + qp[size - 2];
67: }
68: else
69: {
70: count_leading_zeros (cnt, qp[size - 1]);
1.1.1.3 ! ohara 71: cnt -= GMP_NAIL_BITS;
1.1.1.2 maekawa 72:
73: #if BITS_PER_MP_LIMB == 32
74: if (cnt == 0)
75: {
76: hz = qp[size - 1];
77: lz = qp[size - 2];
78: }
79: else
80: {
1.1.1.3 ! ohara 81: hz = ((qp[size - 1] << cnt) | (qp[size - 2] >> GMP_NUMB_BITS - cnt)) & GMP_NUMB_MASK;
! 82: lz = ((qp[size - 2] << cnt) | (qp[size - 3] >> GMP_NUMB_BITS - cnt)) & GMP_NUMB_MASK;
1.1.1.2 maekawa 83: }
84: #if _GMP_IEEE_FLOATS
85: /* Take bits from less significant limbs, but only if they may affect
86: the result. */
87: if ((lz & 0x7ff) == 0x400)
88: {
89: if (cnt != 0)
1.1.1.3 ! ohara 90: lz += (((qp[size - 3] << cnt) & GMP_NUMB_MASK) != 0
! 91: || ! mpn_zero_p (qp, size - 3));
1.1.1.2 maekawa 92: else
93: lz += (! mpn_zero_p (qp, size - 2));
94: }
95: #endif
96: res = MP_BASE_AS_DOUBLE * hz + lz;
1.1.1.3 ! ohara 97: res = __gmp_scale2 (res, (size - 2) * GMP_NUMB_BITS - cnt);
1.1.1.2 maekawa 98: #endif
99: #if BITS_PER_MP_LIMB == 64
100: if (cnt == 0)
101: hz = qp[size - 1];
102: else
1.1.1.3 ! ohara 103: hz = ((qp[size - 1] << cnt) | (qp[size - 2] >> GMP_NUMB_BITS - cnt)) & GMP_NUMB_MASK;
1.1.1.2 maekawa 104: #if _GMP_IEEE_FLOATS
105: if ((hz & 0x7ff) == 0x400)
106: {
107: if (cnt != 0)
1.1.1.3 ! ohara 108: hz += (((qp[size - 2] << cnt) & GMP_NUMB_MASK) != 0
! 109: || ! mpn_zero_p (qp, size - 2));
1.1.1.2 maekawa 110: else
111: hz += (! mpn_zero_p (qp, size - 1));
112: }
113: #endif
114: res = hz;
1.1.1.3 ! ohara 115: res = __gmp_scale2 (res, (size - 1) * GMP_NUMB_BITS - cnt);
1.1.1.2 maekawa 116: #endif
117: }
1.1 maekawa 118:
119: return negative ? -res : res;
120: }
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