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Annotation of OpenXM_contrib/gmp/mpf/set_prc.c, Revision 1.1.1.3

1.1       maekawa     1: /* mpf_set_prec(x) -- Change the precision of x.
                      2:
1.1.1.3 ! ohara       3: Copyright 1993, 1994, 1995, 2000, 2001 Free Software Foundation, Inc.
1.1       maekawa     4:
                      5: This file is part of the GNU MP Library.
                      6:
                      7: The GNU MP Library is free software; you can redistribute it and/or modify
1.1.1.2   maekawa     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
1.1       maekawa    10: option) any later version.
                     11:
                     12: The GNU MP Library is distributed in the hope that it will be useful, but
                     13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
1.1.1.2   maekawa    14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
1.1       maekawa    15: License for more details.
                     16:
1.1.1.2   maekawa    17: You should have received a copy of the GNU Lesser General Public License
1.1       maekawa    18: along with the GNU MP 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:
                     25:
1.1.1.3 ! ohara      26: /* A full new_prec+1 limbs are always retained, even though just new_prec
        !            27:    would satisfy the requested precision.  If size==new_prec+1 then
        !            28:    certainly new_prec+1 should be kept since no copying is needed in that
        !            29:    case.  If just new_prec was kept for size>new_prec+1 it'd be a bit
        !            30:    inconsistent.  */
1.1       maekawa    31:
1.1.1.3 ! ohara      32: void
        !            33: mpf_set_prec (mpf_ptr x, unsigned long int new_prec_in_bits)
        !            34: {
        !            35:   mp_size_t  old_prec, new_prec, new_prec_plus1;
        !            36:   mp_size_t  size, sign;
        !            37:   mp_ptr     xp;
        !            38:
        !            39:   new_prec = __GMPF_BITS_TO_PREC (new_prec_in_bits);
        !            40:   old_prec = PREC(x);
        !            41:
        !            42:   /* do nothing if already the right precision */
        !            43:   if (new_prec == old_prec)
        !            44:     return;
        !            45:
        !            46:   PREC(x) = new_prec;
        !            47:   new_prec_plus1 = new_prec + 1;
        !            48:
        !            49:   /* retain most significant limbs */
        !            50:   sign = SIZ(x);
        !            51:   size = ABS (sign);
        !            52:   xp = PTR(x);
        !            53:   if (size > new_prec_plus1)
1.1       maekawa    54:     {
1.1.1.3 ! ohara      55:       SIZ(x) = (sign >= 0 ? new_prec_plus1 : -new_prec_plus1);
        !            56:       MPN_COPY_INCR (xp, xp + size - new_prec_plus1, new_prec_plus1);
1.1       maekawa    57:     }
                     58:
1.1.1.3 ! ohara      59:   PTR(x) = __GMP_REALLOCATE_FUNC_LIMBS (xp, old_prec+1, new_prec_plus1);
1.1       maekawa    60: }