From: Marcelo Henrique Cerri <marcelo.cerri@xxxxxxxxxxxxx> Add mpi_sub_ui() based on Gnu MP mpz_sub_ui() function from file mpz/aors_ui.h[1] from change id 510b83519d1c adapting the code to the kernel's data structures, helper functions and coding style and also removing the defines used to produce mpz_sub_ui() and mpz_add_ui() from the same code. [1] https://gmplib.org/repo/gmp-6.2/file/510b83519d1c/mpz/aors.h Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@xxxxxxxxxxxxx> Signed-off-by: Stephan Mueller <smueller@xxxxxxxxxx> --- include/linux/mpi.h | 3 ++ lib/mpi/Makefile | 1 + lib/mpi/mpi-sub-ui.c | 78 ++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 82 insertions(+) create mode 100644 lib/mpi/mpi-sub-ui.c diff --git a/include/linux/mpi.h b/include/linux/mpi.h index 7bd6d8af0004..5d906dfbf3ed 100644 --- a/include/linux/mpi.h +++ b/include/linux/mpi.h @@ -63,6 +63,9 @@ int mpi_powm(MPI res, MPI base, MPI exp, MPI mod); int mpi_cmp_ui(MPI u, ulong v); int mpi_cmp(MPI u, MPI v); +/*-- mpi-sub-ui.c --*/ +int mpi_sub_ui(MPI w, MPI u, unsigned long vval); + /*-- mpi-bit.c --*/ void mpi_normalize(MPI a); unsigned mpi_get_nbits(MPI a); diff --git a/lib/mpi/Makefile b/lib/mpi/Makefile index d5874a7f5ff9..43b8fce14079 100644 --- a/lib/mpi/Makefile +++ b/lib/mpi/Makefile @@ -16,6 +16,7 @@ mpi-y = \ mpicoder.o \ mpi-bit.o \ mpi-cmp.o \ + mpi-sub-ui.o \ mpih-cmp.o \ mpih-div.o \ mpih-mul.o \ diff --git a/lib/mpi/mpi-sub-ui.c b/lib/mpi/mpi-sub-ui.c new file mode 100644 index 000000000000..b41b082b5f3e --- /dev/null +++ b/lib/mpi/mpi-sub-ui.c @@ -0,0 +1,78 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* mpi-sub-ui.c - Subtract an unsigned integer from an MPI. + * + * Copyright 1991, 1993, 1994, 1996, 1999-2002, 2004, 2012, 2013, 2015 + * Free Software Foundation, Inc. + * + * This file was based on the GNU MP Library source file: + * https://gmplib.org/repo/gmp-6.2/file/510b83519d1c/mpz/aors_ui.h + * + * The GNU MP Library is free software; you can redistribute it and/or modify + * it under the terms of either: + * + * * the GNU Lesser General Public License as published by the Free + * Software Foundation; either version 3 of the License, or (at your + * option) any later version. + * + * or + * + * * 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. + * + * or both in parallel, as here. + * + * The GNU MP Library 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 copies of the GNU General Public License and the + * GNU Lesser General Public License along with the GNU MP Library. If not, + * see https://www.gnu.org/licenses/. + */ + +#include "mpi-internal.h" + +int mpi_sub_ui(MPI w, MPI u, unsigned long vval) +{ + if (u->nlimbs == 0) { + if (mpi_resize(w, 1) < 0) + return -ENOMEM; + w->d[0] = vval; + w->nlimbs = (vval != 0); + w->sign = (vval != 0); + return 0; + } + + /* If not space for W (and possible carry), increase space. */ + if (mpi_resize(w, u->nlimbs + 1)) + return -ENOMEM; + + if (u->sign) { + mpi_limb_t cy; + + cy = mpihelp_add_1(w->d, u->d, u->nlimbs, (mpi_limb_t) vval); + w->d[u->nlimbs] = cy; + w->nlimbs = u->nlimbs + cy; + w->sign = 1; + } else { + /* The signs are different. Need exact comparison to determine + * which operand to subtract from which. + */ + if (u->nlimbs == 1 && u->d[0] < vval) { + w->d[0] = vval - u->d[0]; + w->nlimbs = 1; + w->sign = 1; + } else { + mpihelp_sub_1(w->d, u->d, u->nlimbs, (mpi_limb_t) vval); + /* Size can decrease with at most one limb. */ + w->nlimbs = (u->nlimbs - (w->d[u->nlimbs - 1] == 0)); + w->sign = 0; + } + } + + mpi_normalize(w); + return 0; +} +EXPORT_SYMBOL_GPL(mpi_sub_ui); -- 2.26.2
