| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* mpihelp-mul_3.c - MPI helper functions |
| * Copyright (C) 1994, 1996, 1997, 1998, 2001 Free Software Foundation, Inc. |
| * This file is part of GnuPG. |
| * 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" |
| mpihelp_submul_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, |
| mpi_size_t s1_size, mpi_limb_t s2_limb) |
| mpi_limb_t prod_high, prod_low; |
| /* The loop counter and index J goes from -SIZE to -1. This way |
| * the loop becomes faster. */ |
| umul_ppmm(prod_high, prod_low, s1_ptr[j], s2_limb); |
| cy_limb = (prod_low < cy_limb ? 1 : 0) + prod_high; |
| cy_limb += prod_low > x ? 1 : 0; |