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Annotation of OpenXM_contrib/gmp/mpz/ui_sub.c, Revision 1.1

1.1     ! ohara       1: /* mpz_ui_sub -- Subtract an unsigned one-word integer and an mpz_t.
        !             2:
        !             3: Copyright 2002 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 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 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 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 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: void
        !            26: mpz_ui_sub (mpz_ptr w, unsigned long int uval, mpz_srcptr v)
        !            27: {
        !            28:   mp_ptr vp, wp;
        !            29:   mp_size_t vn, wn;
        !            30:   mp_limb_t cy;
        !            31:
        !            32: #if GMP_NAIL_BITS != 0
        !            33:   if (uval > GMP_NUMB_MAX)
        !            34:     {
        !            35:       mpz_t u;
        !            36:       mp_limb_t ul[2];
        !            37:       PTR(u) = ul;
        !            38:       ul[0] = uval & GMP_NUMB_MASK;
        !            39:       ul[1] = uval >> GMP_NUMB_BITS;
        !            40:       SIZ(u) = 2;
        !            41:       mpz_sub (w, u, v);
        !            42:       return;
        !            43:     }
        !            44: #endif
        !            45:
        !            46:   vp = PTR(v);
        !            47:   vn = SIZ(v);
        !            48:
        !            49:   wp = PTR(w);
        !            50:
        !            51:   if (vn > 1)
        !            52:     {
        !            53:       wp = MPZ_REALLOC (w, vn);
        !            54:       vp = PTR(v);
        !            55:       mpn_sub_1 (wp, vp, vn, (mp_limb_t) uval);
        !            56:       wn = -(vn - (wp[vn - 1] == 0));
        !            57:     }
        !            58:   else if (vn == 1)
        !            59:     {
        !            60:       if (uval >= vp[0])
        !            61:        {
        !            62:          wp[0] = uval - vp[0];
        !            63:          wn = wp[0] != 0;
        !            64:        }
        !            65:       else
        !            66:        {
        !            67:          wp[0] = vp[0] - uval;
        !            68:          wn = -1;
        !            69:        }
        !            70:     }
        !            71:   else if (vn == 0)
        !            72:     {
        !            73:       wp[0] = uval;
        !            74:       wn = uval != 0;
        !            75:     }
        !            76:   else /* (vn < 0) */
        !            77:     {
        !            78:       vn = -vn;
        !            79:       wp = MPZ_REALLOC (w, vn + 1);
        !            80:       vp = PTR(v);
        !            81:       cy = mpn_add_1 (wp, vp, vn, (mp_limb_t) uval);
        !            82:       wp[vn] = cy;
        !            83:       wn = vn + (cy != 0);
        !            84:     }
        !            85:
        !            86:   SIZ(w) = wn;
        !            87: }