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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: }