/*      $OpenBSD: bn_arch.h,v 1.2 2023/06/24 15:51:47 jsing Exp $ */
/*
 * Copyright (c) 2023 Joel Sing <jsing@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <openssl/bn.h>

#ifndef HEADER_BN_ARCH_H
#define HEADER_BN_ARCH_H

#ifndef OPENSSL_NO_ASM

#if defined(__GNUC__)

#define HAVE_BN_SUBW

static inline void
bn_subw(BN_ULONG a, BN_ULONG b, BN_ULONG *out_borrow, BN_ULONG *out_r0)
{
        BN_ULONG borrow, r0;

        __asm__ (
            "mov  %[borrow], #0 \n"
            "subs %[r0], %[a], %[b] \n"
            "sbc  %[borrow], %[borrow], #0 \n"
            "neg  %[borrow], %[borrow] \n"
            : [borrow]"=&r"(borrow), [r0]"=r"(r0)
            : [a]"r"(a), [b]"r"(b)
            : "cc");

        *out_borrow = borrow;
        *out_r0 = r0;
}

#define HAVE_BN_SUBW_SUBW

static inline void
bn_subw_subw(BN_ULONG a, BN_ULONG b, BN_ULONG c, BN_ULONG *out_borrow,
    BN_ULONG *out_r0)
{
        BN_ULONG borrow, r0;

        __asm__ (
            "mov  %[borrow], #0 \n"
            "subs %[r0], %[a], %[b] \n"
            "sbc  %[borrow], %[borrow], #0 \n"
            "subs %[r0], %[r0], %[c] \n"
            "sbc  %[borrow], %[borrow], #0 \n"
            "neg  %[borrow], %[borrow] \n"
            : [borrow]"=&r"(borrow), [r0]"=&r"(r0)
            : [a]"r"(a), [b]"r"(b), [c]"r"(c)
            : "cc");

        *out_borrow = borrow;
        *out_r0 = r0;
}

#endif /* __GNUC__ */

#endif
#endif