From 2a598d0b2800aa23ba51adcf060cec524aaa63b2 Mon Sep 17 00:00:00 2001
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Fri, 4 Aug 2023 17:24:34 +0800
Subject: crypto: lib - Move mpi into lib/crypto
As lib/mpi is mostly used by crypto code, move it under lib/crypto
so that patches touching it get directed to the right mailing list.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
lib/crypto/mpi/mpi-sub-ui.c | 78 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 78 insertions(+)
create mode 100644 lib/crypto/mpi/mpi-sub-ui.c
(limited to 'lib/crypto/mpi/mpi-sub-ui.c')
diff --git a/lib/crypto/mpi/mpi-sub-ui.c b/lib/crypto/mpi/mpi-sub-ui.c
new file mode 100644
index 000000000000..b41b082b5f3e
--- /dev/null
+++ b/lib/crypto/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);
--
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