1/*	$OpenBSD: bn_arch.h,v 1.4 2023/02/16 10:41:03 jsing Exp $ */
2/*
3 * Copyright (c) 2023 Joel Sing <jsing@openbsd.org>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18#ifndef HEADER_BN_ARCH_H
19#define HEADER_BN_ARCH_H
20
21#ifndef OPENSSL_NO_ASM
22
23#if 0 /* Needs testing and enabling. */
24#if defined(__GNUC__)
25#define HAVE_BN_MULW
26
27static inline void
28bn_mulw(BN_ULONG a, BN_ULONG b, BN_ULONG *out_r1, BN_ULONG *out_r0)
29{
30	BN_ULONG r1, r0;
31
32	/* Unsigned multiplication using a mulhdu/mul pair. */
33	__asm__ ("mulhdu %0, %2, %3; mul %1, %2, %3"
34	    : "=&r"(r1), "=r"(r0)
35	    : "r"(a), "r"(b));
36
37	*out_r1 = r1;
38	*out_r0 = r0;
39}
40#endif /* __GNUC__ */
41#endif
42
43#endif
44#endif
45