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Annotation of OpenXM/src/kan96xx/gmp-2.0.2/mpz/sub.c, Revision 1.1

1.1     ! maekawa     1: /* mpz_sub -- Subtract two integers.
        !             2:
        !             3: Copyright (C) 1991, 1993, 1994, 1996 Free Software Foundation, Inc.
        !             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
        !             8: it under the terms of the GNU Library General Public License as published by
        !             9: the Free Software Foundation; either version 2 of the License, or (at your
        !            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
        !            14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
        !            15: License for more details.
        !            16:
        !            17: You should have received a copy of the GNU Library General Public License
        !            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: #ifndef BERKELEY_MP
        !            26: void
        !            27: #if __STDC__
        !            28: mpz_sub (mpz_ptr w, mpz_srcptr u, mpz_srcptr v)
        !            29: #else
        !            30: mpz_sub (w, u, v)
        !            31:      mpz_ptr w;
        !            32:      mpz_srcptr u;
        !            33:      mpz_srcptr v;
        !            34: #endif
        !            35: #else /* BERKELEY_MP */
        !            36: void
        !            37: #if __STDC__
        !            38: msub (mpz_srcptr u, mpz_srcptr v, mpz_ptr w)
        !            39: #else
        !            40: msub (u, v, w)
        !            41:      mpz_srcptr u;
        !            42:      mpz_srcptr v;
        !            43:      mpz_ptr w;
        !            44: #endif
        !            45: #endif /* BERKELEY_MP */
        !            46: {
        !            47:   mp_srcptr up, vp;
        !            48:   mp_ptr wp;
        !            49:   mp_size_t usize, vsize, wsize;
        !            50:   mp_size_t abs_usize;
        !            51:   mp_size_t abs_vsize;
        !            52:
        !            53:   usize = u->_mp_size;
        !            54:   vsize = -v->_mp_size;                /* The "-" makes the difference from mpz_add */
        !            55:   abs_usize = ABS (usize);
        !            56:   abs_vsize = ABS (vsize);
        !            57:
        !            58:   if (abs_usize < abs_vsize)
        !            59:     {
        !            60:       /* Swap U and V. */
        !            61:       {const __mpz_struct *t = u; u = v; v = t;}
        !            62:       {mp_size_t t = usize; usize = vsize; vsize = t;}
        !            63:       {mp_size_t t = abs_usize; abs_usize = abs_vsize; abs_vsize = t;}
        !            64:     }
        !            65:
        !            66:   /* True: ABS_USIZE >= ABS_VSIZE.  */
        !            67:
        !            68:   /* If not space for w (and possible carry), increase space.  */
        !            69:   wsize = abs_usize + 1;
        !            70:   if (w->_mp_alloc < wsize)
        !            71:     _mpz_realloc (w, wsize);
        !            72:
        !            73:   /* These must be after realloc (u or v may be the same as w).  */
        !            74:   up = u->_mp_d;
        !            75:   vp = v->_mp_d;
        !            76:   wp = w->_mp_d;
        !            77:
        !            78:   if ((usize ^ vsize) < 0)
        !            79:     {
        !            80:       /* U and V have different sign.  Need to compare them to determine
        !            81:         which operand to subtract from which.  */
        !            82:
        !            83:       /* This test is right since ABS_USIZE >= ABS_VSIZE.  */
        !            84:       if (abs_usize != abs_vsize)
        !            85:        {
        !            86:          mpn_sub (wp, up, abs_usize, vp, abs_vsize);
        !            87:          wsize = abs_usize;
        !            88:          MPN_NORMALIZE (wp, wsize);
        !            89:          if (usize < 0)
        !            90:            wsize = -wsize;
        !            91:        }
        !            92:       else if (mpn_cmp (up, vp, abs_usize) < 0)
        !            93:        {
        !            94:          mpn_sub_n (wp, vp, up, abs_usize);
        !            95:          wsize = abs_usize;
        !            96:          MPN_NORMALIZE (wp, wsize);
        !            97:          if (usize >= 0)
        !            98:            wsize = -wsize;
        !            99:        }
        !           100:       else
        !           101:        {
        !           102:          mpn_sub_n (wp, up, vp, abs_usize);
        !           103:          wsize = abs_usize;
        !           104:          MPN_NORMALIZE (wp, wsize);
        !           105:          if (usize < 0)
        !           106:            wsize = -wsize;
        !           107:        }
        !           108:     }
        !           109:   else
        !           110:     {
        !           111:       /* U and V have same sign.  Add them.  */
        !           112:       mp_limb_t cy_limb = mpn_add (wp, up, abs_usize, vp, abs_vsize);
        !           113:       wp[abs_usize] = cy_limb;
        !           114:       wsize = abs_usize + cy_limb;
        !           115:       if (usize < 0)
        !           116:        wsize = -wsize;
        !           117:     }
        !           118:
        !           119:   w->_mp_size = wsize;
        !           120: }