Annotation of OpenXM_contrib/gmp/mpf/get_si.c, Revision 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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