Annotation of OpenXM_contrib/gmp/mpf/get_si.c, Revision 1.1.1.1
1.1 ohara 1: /* mpf_get_si -- mpf to long conversion */
2:
3: /*
4: Copyright 2001, 2002 Free Software Foundation, Inc.
5:
6: This file is part of the GNU MP Library.
7:
8: The GNU MP Library is free software; you can redistribute it and/or modify
9: it under the terms of the GNU Lesser General Public License as published by
10: the Free Software Foundation; either version 2.1 of the License, or (at your
11: option) any later version.
12:
13: The GNU MP Library is distributed in the hope that it will be useful, but
14: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15: or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
16: License for more details.
17:
18: You should have received a copy of the GNU Lesser General Public License
19: along with the GNU MP Library; see the file COPYING.LIB. If not, write to
20: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
21: MA 02111-1307, USA.
22: */
23:
24: #include "gmp.h"
25: #include "gmp-impl.h"
26:
27:
28: /* Any fraction bits are truncated, meaning simply discarded.
29:
30: For values bigger than a long, the low bits are returned, like
31: mpz_get_si, but this isn't documented.
32:
33: Notice this is equivalent to mpz_set_f + mpz_get_si. */
34:
35: long
36: mpf_get_si (mpf_srcptr f)
37: {
38: mp_exp_t exp;
39: mp_size_t size, abs_size;
40: mp_ptr fp;
41: mp_limb_t fl;
42:
43: size = SIZ (f);
44: if (size == 0)
45: return 0L;
46:
47: /* fraction alone truncates to zero */
48: exp = EXP (f);
49: if (exp <= 0)
50: return 0L;
51:
52: /* exponent bigger than available data means low limb zero */
53: abs_size = ABS (size);
54: if (exp > abs_size)
55: return 0L;
56:
57: fp = PTR(f);
58: fl = fp[abs_size - exp];
59:
60: #if GMP_NAIL_BITS != 0
61: if (ULONG_MAX > GMP_NUMB_MAX != 0 && exp > 1)
62: fl |= fp[abs_size - exp + 1] << GMP_NUMB_BITS;
63: #endif
64:
65: if (size > 0)
66: return fl & LONG_MAX;
67: else
68: /* this form necessary to correctly handle -0x80..00 */
69: return ~ ((fl - 1) & LONG_MAX);
70: }
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