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Annotation of OpenXM_contrib/gmp/mpfr/ui_sub.c, Revision 1.1.1.1

1.1       ohara       1: /* mpfr_ui_sub -- subtract a floating-point number from an integer
                      2:
                      3: Copyright 2000, 2001, 2002 Free Software Foundation, Inc.
                      4:
                      5: This file is part of the MPFR Library.
                      6:
                      7: The MPFR Library is free software; you can redistribute it and/or modify
                      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
                     10: option) any later version.
                     11:
                     12: The MPFR Library is distributed in the hope that it will be useful, but
                     13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
                     14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
                     15: License for more details.
                     16:
                     17: You should have received a copy of the GNU Lesser General Public License
                     18: along with the MPFR 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"
                     24: #include "longlong.h"
                     25: #include "mpfr.h"
                     26: #include "mpfr-impl.h"
                     27:
                     28: int
                     29: mpfr_ui_sub (mpfr_ptr y, unsigned long int u, mpfr_srcptr x, mp_rnd_t rnd_mode)
                     30: {
                     31:   mpfr_t uu;
                     32:   mp_limb_t up[1];
                     33:   unsigned long cnt;
                     34:
                     35:   if (MPFR_IS_NAN(x))
                     36:     {
                     37:       MPFR_SET_NAN(y);
                     38:       MPFR_RET_NAN;
                     39:     }
                     40:
                     41:   MPFR_CLEAR_NAN(y);
                     42:
                     43:   if (MPFR_IS_INF(x))
                     44:     {
                     45:       MPFR_SET_INF(y);
                     46:       if (MPFR_SIGN(x) == MPFR_SIGN(y))
                     47:        MPFR_CHANGE_SIGN(y);
                     48:       MPFR_RET(0); /* +/-infinity is exact */
                     49:     }
                     50:
                     51:   if (u) {
                     52:     MPFR_INIT1 (up, uu, BITS_PER_MP_LIMB, 1);
                     53:     count_leading_zeros (cnt, (mp_limb_t) u);
                     54:     *up = (mp_limb_t) u << cnt;
                     55:     MPFR_EXP(uu) = BITS_PER_MP_LIMB - cnt;
                     56:
                     57:     return mpfr_sub (y, uu, x, rnd_mode);
                     58:   }
                     59:   else
                     60:     return mpfr_neg (y, x, rnd_mode); /* if u=0, then set y to -x */
                     61: }