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Annotation of OpenXM_contrib/gmp/mpn/generic/mul_1.c, Revision 1.1.1.1

1.1       maekawa     1: /* mpn_mul_1 -- Multiply a limb vector with a single limb and
                      2:    store the product in a second limb vector.
                      3:
                      4: Copyright (C) 1991, 1992, 1993, 1994, 1996 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: #include "longlong.h"
                     26:
                     27: mp_limb_t
                     28: mpn_mul_1 (res_ptr, s1_ptr, s1_size, s2_limb)
                     29:      register mp_ptr res_ptr;
                     30:      register mp_srcptr s1_ptr;
                     31:      mp_size_t s1_size;
                     32:      register mp_limb_t s2_limb;
                     33: {
                     34:   register mp_limb_t cy_limb;
                     35:   register mp_size_t j;
                     36:   register mp_limb_t prod_high, prod_low;
                     37:
                     38:   /* The loop counter and index J goes from -S1_SIZE to -1.  This way
                     39:      the loop becomes faster.  */
                     40:   j = -s1_size;
                     41:
                     42:   /* Offset the base pointers to compensate for the negative indices.  */
                     43:   s1_ptr -= j;
                     44:   res_ptr -= j;
                     45:
                     46:   cy_limb = 0;
                     47:   do
                     48:     {
                     49:       umul_ppmm (prod_high, prod_low, s1_ptr[j], s2_limb);
                     50:
                     51:       prod_low += cy_limb;
                     52:       cy_limb = (prod_low < cy_limb) + prod_high;
                     53:
                     54:       res_ptr[j] = prod_low;
                     55:     }
                     56:   while (++j != 0);
                     57:
                     58:   return cy_limb;
                     59: }