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Annotation of OpenXM/src/kan96xx/gmp-2.0.2/mpq/inv.c, Revision 1.1.1.1

1.1       maekawa     1: /* mpq_inv(dest,src) -- invert a rational number, i.e. set DEST to SRC
                      2:    with the numerator and denominator swapped.
                      3:
                      4: Copyright (C) 1991, 1994, 1995 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 Library General Public License as published by
                     10: the Free Software Foundation; either version 2 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 Library General Public
                     16: License for more details.
                     17:
                     18: You should have received a copy of the GNU Library 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: #include "gmp.h"
                     24: #include "gmp-impl.h"
                     25:
                     26: void
                     27: #if __STDC__
                     28: mpq_inv (MP_RAT *dest, const MP_RAT *src)
                     29: #else
                     30: mpq_inv (dest, src)
                     31:      MP_RAT *dest;
                     32:      const MP_RAT *src;
                     33: #endif
                     34: {
                     35:   mp_size_t num_size = src->_mp_num._mp_size;
                     36:   mp_size_t den_size = src->_mp_den._mp_size;
                     37:
                     38:   if (num_size == 0)
                     39:     num_size = 1 / num_size;   /* Divide by zero!  */
                     40:
                     41:   if (num_size < 0)
                     42:     {
                     43:       num_size = -num_size;
                     44:       den_size = -den_size;
                     45:     }
                     46:   dest->_mp_den._mp_size = num_size;
                     47:   dest->_mp_num._mp_size = den_size;
                     48:
                     49:   /* If dest == src we may just swap the numerator and denominator, but
                     50:      we have to ensure the new denominator is positive.  */
                     51:
                     52:   if (dest == src)
                     53:     {
                     54:       mp_size_t alloc = dest->_mp_num._mp_alloc;
                     55:       mp_ptr limb_ptr = dest->_mp_num._mp_d;
                     56:
                     57:       dest->_mp_num._mp_alloc = dest->_mp_den._mp_alloc;
                     58:       dest->_mp_num._mp_d = dest->_mp_den._mp_d;
                     59:
                     60:       dest->_mp_den._mp_alloc = alloc;
                     61:       dest->_mp_den._mp_d = limb_ptr;
                     62:     }
                     63:   else
                     64:     {
                     65:       den_size = ABS (den_size);
                     66:       if (dest->_mp_num._mp_alloc < den_size)
                     67:        _mpz_realloc (&(dest->_mp_num), den_size);
                     68:
                     69:       if (dest->_mp_den._mp_alloc < num_size)
                     70:        _mpz_realloc (&(dest->_mp_den), num_size);
                     71:
                     72:       MPN_COPY (dest->_mp_num._mp_d, src->_mp_den._mp_d, den_size);
                     73:       MPN_COPY (dest->_mp_den._mp_d, src->_mp_num._mp_d, num_size);
                     74:     }
                     75: }