1/*	$OpenBSD: bn_arch.h,v 1.7 2023/07/09 10:37:32 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#include <openssl/bn.h>
19
20#ifndef HEADER_BN_ARCH_H
21#define HEADER_BN_ARCH_H
22
23#ifndef OPENSSL_NO_ASM
24
25#if defined(__GNUC__)
26
27#define HAVE_BN_ADDW
28
29static inline void
30bn_addw(BN_ULONG a, BN_ULONG b, BN_ULONG *out_r1, BN_ULONG *out_r0)
31{
32	BN_ULONG carry, r0;
33
34	__asm__ (
35	    "add   %[r0], %[a], %[b] \n"
36	    "sltu  %[carry], %[r0], %[a] \n"
37	    : [carry]"=r"(carry), [r0]"=&r"(r0)
38	    : [a]"r"(a), [b]"r"(b));
39
40	*out_r1 = carry;
41	*out_r0 = r0;
42}
43
44#define HAVE_BN_MULW
45
46static inline void
47bn_mulw(BN_ULONG a, BN_ULONG b, BN_ULONG *out_r1, BN_ULONG *out_r0)
48{
49	BN_ULONG r1, r0;
50
51	/*
52	 * Unsigned multiplication using a mulh/mul pair. Note that the order
53	 * of these instructions is important, as they can potentially be fused
54	 * into a single operation.
55	 */
56	__asm__ (
57	    "mulhu %[r1], %[a], %[b] \n"
58	    "mul   %[r0], %[a], %[b] \n"
59	    : [r1]"=&r"(r1), [r0]"=r"(r0)
60	    : [a]"r"(a), [b]"r"(b));
61
62	*out_r1 = r1;
63	*out_r0 = r0;
64}
65
66#define HAVE_BN_SUBW
67
68static inline void
69bn_subw(BN_ULONG a, BN_ULONG b, BN_ULONG *out_borrow, BN_ULONG *out_r0)
70{
71	BN_ULONG borrow, r0;
72
73	__asm__ (
74	    "sub   %[r0], %[a], %[b] \n"
75	    "sltu  %[borrow], %[a], %[r0] \n"
76	    : [borrow]"=r"(borrow), [r0]"=&r"(r0)
77	    : [a]"r"(a), [b]"r"(b));
78
79	*out_borrow = borrow;
80	*out_r0 = r0;
81}
82
83#endif /* __GNUC__ */
84
85#endif
86#endif
87