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Annotation of OpenXM_contrib/gmp/mpz/sub.c, Revision 1.1.1.2

1.1       maekawa     1: /* mpz_sub -- Subtract two integers.
                      2:
1.1.1.2 ! maekawa     3: Copyright (C) 1991, 1993, 1994, 1996, 2000 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"
1.1.1.2 ! maekawa    24: #ifdef BERKELEY_MP
        !            25: #include "mp.h"
        !            26: #endif
1.1       maekawa    27:
                     28: #ifndef BERKELEY_MP
                     29: void
                     30: #if __STDC__
                     31: mpz_sub (mpz_ptr w, mpz_srcptr u, mpz_srcptr v)
                     32: #else
                     33: mpz_sub (w, u, v)
                     34:      mpz_ptr w;
                     35:      mpz_srcptr u;
                     36:      mpz_srcptr v;
                     37: #endif
                     38: #else /* BERKELEY_MP */
                     39: void
                     40: #if __STDC__
                     41: msub (mpz_srcptr u, mpz_srcptr v, mpz_ptr w)
                     42: #else
                     43: msub (u, v, w)
                     44:      mpz_srcptr u;
                     45:      mpz_srcptr v;
                     46:      mpz_ptr w;
                     47: #endif
                     48: #endif /* BERKELEY_MP */
                     49: {
                     50:   mp_srcptr up, vp;
                     51:   mp_ptr wp;
                     52:   mp_size_t usize, vsize, wsize;
                     53:   mp_size_t abs_usize;
                     54:   mp_size_t abs_vsize;
                     55:
                     56:   usize = u->_mp_size;
                     57:   vsize = -v->_mp_size;                /* The "-" makes the difference from mpz_add */
                     58:   abs_usize = ABS (usize);
                     59:   abs_vsize = ABS (vsize);
                     60:
                     61:   if (abs_usize < abs_vsize)
                     62:     {
                     63:       /* Swap U and V. */
1.1.1.2 ! maekawa    64:       MPZ_SRCPTR_SWAP (u, v);
        !            65:       MP_SIZE_T_SWAP (usize, vsize);
        !            66:       MP_SIZE_T_SWAP (abs_usize, abs_vsize);
1.1       maekawa    67:     }
                     68:
                     69:   /* True: ABS_USIZE >= ABS_VSIZE.  */
                     70:
                     71:   /* If not space for w (and possible carry), increase space.  */
                     72:   wsize = abs_usize + 1;
                     73:   if (w->_mp_alloc < wsize)
                     74:     _mpz_realloc (w, wsize);
                     75:
                     76:   /* These must be after realloc (u or v may be the same as w).  */
                     77:   up = u->_mp_d;
                     78:   vp = v->_mp_d;
                     79:   wp = w->_mp_d;
                     80:
                     81:   if ((usize ^ vsize) < 0)
                     82:     {
                     83:       /* U and V have different sign.  Need to compare them to determine
                     84:         which operand to subtract from which.  */
                     85:
                     86:       /* This test is right since ABS_USIZE >= ABS_VSIZE.  */
                     87:       if (abs_usize != abs_vsize)
                     88:        {
                     89:          mpn_sub (wp, up, abs_usize, vp, abs_vsize);
                     90:          wsize = abs_usize;
                     91:          MPN_NORMALIZE (wp, wsize);
                     92:          if (usize < 0)
                     93:            wsize = -wsize;
                     94:        }
                     95:       else if (mpn_cmp (up, vp, abs_usize) < 0)
                     96:        {
                     97:          mpn_sub_n (wp, vp, up, abs_usize);
                     98:          wsize = abs_usize;
                     99:          MPN_NORMALIZE (wp, wsize);
                    100:          if (usize >= 0)
                    101:            wsize = -wsize;
                    102:        }
                    103:       else
                    104:        {
                    105:          mpn_sub_n (wp, up, vp, abs_usize);
                    106:          wsize = abs_usize;
                    107:          MPN_NORMALIZE (wp, wsize);
                    108:          if (usize < 0)
                    109:            wsize = -wsize;
                    110:        }
                    111:     }
                    112:   else
                    113:     {
                    114:       /* U and V have same sign.  Add them.  */
                    115:       mp_limb_t cy_limb = mpn_add (wp, up, abs_usize, vp, abs_vsize);
                    116:       wp[abs_usize] = cy_limb;
                    117:       wsize = abs_usize + cy_limb;
                    118:       if (usize < 0)
                    119:        wsize = -wsize;
                    120:     }
                    121:
                    122:   w->_mp_size = wsize;
                    123: }