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lib/mpi/generic_mpih-mul2.c
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/* mpihelp-mul_2.c - MPI helper functions * Copyright (C) 1994, 1996, 1997, 1998, 2001 Free Software Foundation, Inc. * * This file is part of GnuPG. * * GnuPG is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * GnuPG 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 General Public License for more details. * * You should have received a copy of the GNU 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. * The GNU MP Library itself is published under the LGPL; * however I decided to publish this code under the plain GPL. */ #include "mpi-internal.h" #include "longlong.h" mpi_limb_t mpihelp_addmul_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; mpi_limb_t x; /* The loop counter and index J goes from -SIZE to -1. This way * the loop becomes faster. */ j = -s1_size; res_ptr -= j; s1_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; x = res_ptr[j]; prod_low = x + prod_low; cy_limb += prod_low < x ? 1 : 0; res_ptr[j] = prod_low; } while (++j); return cy_limb; } |