cmpxchg.h

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/*
 * Atomics xchg/cmpxchg for PKUnity SoC and UniCore ISA
 *
 * Copyright (C) 2001-2012 GUAN Xue-tao
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#ifndef __UNICORE_CMPXCHG_H__
#define __UNICORE_CMPXCHG_H__

/*
 * Generate a link failure on undefined symbol if the pointer points to a value
 * of unsupported size.
 */
extern void __xchg_bad_pointer(void);

static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
        int size)
{
    unsigned long ret;

    switch (size) {
    case 1:
        asm volatile("swapb %0, %1, [%2]"
            : "=&r" (ret)
            : "r" (x), "r" (ptr)
            : "memory", "cc");
        break;
    case 4:
        asm volatile("swapw %0, %1, [%2]"
            : "=&r" (ret)
            : "r" (x), "r" (ptr)
            : "memory", "cc");
        break;
    default:
        __xchg_bad_pointer();
    }

    return ret;
}

#define xchg(ptr, x) \
    ((__typeof__(*(ptr)))__xchg((unsigned long)(x), (ptr), sizeof(*(ptr))))

#include <asm-generic/cmpxchg-local.h>

/*
 * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
 * them available.
 */
#define cmpxchg_local(ptr, o, n)                    \
        ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), \
        (unsigned long)(o), (unsigned long)(n), sizeof(*(ptr))))
#define cmpxchg64_local(ptr, o, n)                  \
        __cmpxchg64_local_generic((ptr), (o), (n))

#include <asm-generic/cmpxchg.h>

#endif /* __UNICORE_CMPXCHG_H__ */