/*
 * Copyright (c) 2020 François Tigeot <ftigeot@wolfpond.org>
 * All rights reserved.
 *
 * 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 unmodified, 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 AUTHOR ``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 AUTHOR 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 _ASM_CMPXCHG_H_
#define _ASM_CMPXCHG_H_

#define xchg(ptr, value)                                \
({                                                      \
        __typeof(value) __ret = (value);                \
                                                        \
        switch (sizeof(value)) {                        \
        case 8:                                         \
                __asm __volatile("xchgq %0, %1"         \
                    : "+r" (__ret), "+m" (*(ptr))       \
                    : : "memory");                      \
                break;                                  \
        case 4:                                         \
                __asm __volatile("xchgl %0, %1"         \
                    : "+r" (__ret), "+m" (*(ptr))       \
                    : : "memory");                      \
                break;                                  \
        case 2:                                         \
                __asm __volatile("xchgw %0, %1"         \
                    : "+r" (__ret), "+m" (*(ptr))       \
                    : : "memory");                      \
                break;                                  \
        case 1:                                         \
                __asm __volatile("xchgb %0, %1"         \
                    : "+r" (__ret), "+m" (*(ptr))       \
                    : : "memory");                      \
                break;                                  \
        default:                                        \
                panic("xchg(): invalid size %ld\n", sizeof(value)); \
        }                                               \
                                                        \
        __ret;                                          \
})

#endif  /* _ASM_CMPXCHG_H_ */