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Diffstat (limited to 'mpi/generic/mpih-mul1.c')
| -rw-r--r-- | mpi/generic/mpih-mul1.c | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/mpi/generic/mpih-mul1.c b/mpi/generic/mpih-mul1.c new file mode 100644 index 00000000..e84eccce --- /dev/null +++ b/mpi/generic/mpih-mul1.c @@ -0,0 +1,62 @@ +/* mpihelp-mul_1.c - MPI helper functions + * Copyright (c) 1997 by Werner Koch (dd9jn) + * Copyright (C) 1994, 1996 Free Software Foundation, Inc. + * + * This file is part of G10. + * + * G10 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. + * + * G10 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 <config.h> +#include <stdio.h> +#include <stdlib.h> +#include "mpi-internal.h" +#include "longlong.h" + +mpi_limb_t +mpihelp_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; +} + |