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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: }