/*      $NetBSD: byte_swap.h,v 1.17 2025/12/15 22:10:33 nia Exp $       */

/*-
 * Copyright (c) 1997, 1999, 2002 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Charles M. Hannum, Neil A. Carson, and Jason R. Thorpe.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef _ARM_BYTE_SWAP_H_
#define _ARM_BYTE_SWAP_H_

#ifdef _LOCORE

#if defined(_ARM_ARCH_6) || defined(_ARM_ARCH_7)

#define BSWAP16(_src, _dst, _tmp)               \
        rev16   _dst, _src
#define BSWAP32(_src, _dst, _tmp)               \
        rev     _dst, _src

#else

#define BSWAP16(_src, _dst, _tmp)               \
        mov     _tmp, _src, ror #8              ;\
        orr     _tmp, _tmp, _tmp, lsr #16       ;\
        bic     _dst, _tmp, _tmp, lsl #16

#define BSWAP32(_src, _dst, _tmp)               \
        eor     _tmp, _src, _src, ror #16       ;\
        bic     _tmp, _tmp, #0x00FF0000         ;\
        mov     _dst, _src, ror #8              ;\
        eor     _dst, _dst, _tmp, lsr #8

#endif


#else

#ifdef __GNUC__
#include <sys/stdint.h>
__BEGIN_DECLS

#define __BYTE_SWAP_U32_VARIABLE __byte_swap_u32_variable
static __inline uint32_t
__byte_swap_u32_variable(uint32_t v)
{
        uint32_t t1;

#ifdef _ARM_ARCH_6
        if (!__builtin_constant_p(v)) {
                __asm("rev\t%0, %1" : "=r" (v) : "0" (v));
                return v;
        }
#endif

        t1 = v ^ ((v << 16) | (v >> 16));
        t1 &= 0xff00ffffU;
        v = (v >> 8) | (v << 24);
        v ^= (t1 >> 8);

        return v;
}

#define __BYTE_SWAP_U16_VARIABLE __byte_swap_u16_variable
static __inline uint16_t
__byte_swap_u16_variable(uint16_t v)
{

#ifdef _ARM_ARCH_6
        if (!__builtin_constant_p(v)) {
                uint32_t v32 = v;
                __asm("rev16\t%0, %1" : "=r" (v32) : "0" (v32));
                return (uint16_t)v32;
        }
#elif !defined(__thumb__) && 0  /* gcc produces decent code for this */
        if (!__builtin_constant_p(v)) {
                uint32_t v0 = v;
                __asm volatile(
                        "mov    %0, %1, ror #8\n"
                        "orr    %0, %0, %0, lsr #16\n"
                        "bic    %0, %0, %0, lsl #16"
                : "=&r" (v0)
                : "0" (v0));
                return (uint16_t)v0;
        }
#endif
        v &= 0xffff;
        v = (uint16_t)((v >> 8) | (v << 8));

        return v;
}

__END_DECLS
#endif

#endif  /* _LOCORE */

#endif /* _ARM_BYTE_SWAP_H_ */