| /* mpihelp-mul_1.c - MPI helper functions |
| * Copyright (C) 1994, 1996, 1997, 1998, 2001, |
| * 2002 Free Software Foundation, Inc. |
| * |
| * This file is part of Libgcrypt. |
| * |
| * Libgcrypt is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU Lesser General Public License as |
| * published by the Free Software Foundation; either version 2.1 of |
| * the License, or (at your option) any later version. |
| * |
| * Libgcrypt is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with this program; if not, write to the Free Software |
| * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA |
| * |
| * Note: This code is heavily based on the GNU MP Library. |
| * Actually it's the same code with only minor changes in the |
| * way the data is stored; this is to support the abstraction |
| * of an optional secure memory allocation which may be used |
| * to avoid revealing of sensitive data due to paging etc. |
| */ |
| |
| #include <config.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include "mpi-internal.h" |
| #include "longlong.h" |
| |
| mpi_limb_t |
| _gcry_mpih_mul_1( mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size, |
| mpi_limb_t s2_limb) |
| { |
| mpi_limb_t cy_limb; |
| mpi_size_t j; |
| mpi_limb_t prod_high, prod_low; |
| |
| /* The loop counter and index J goes from -S1_SIZE to -1. This way |
| * the loop becomes faster. */ |
| j = -s1_size; |
| |
| /* Offset the base pointers to compensate for the negative indices. */ |
| s1_ptr -= j; |
| res_ptr -= j; |
| |
| cy_limb = 0; |
| do |
| { |
| umul_ppmm( prod_high, prod_low, s1_ptr[j], s2_limb ); |
| prod_low += cy_limb; |
| cy_limb = (prod_low < cy_limb?1:0) + prod_high; |
| res_ptr[j] = prod_low; |
| } |
| while( ++j ); |
| |
| return cy_limb; |
| } |
| |