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Annotation of OpenXM_contrib/gmp/mpz/ui_sub.c, Revision 1.1.1.1

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: }