/*      $OpenBSD: _atomic_lock.c,v 1.1 2017/08/15 06:13:24 guenther Exp $       */

/*
 * Atomic lock for mips
 * Written by Miodrag Vallat <miod@openbsd.org> - placed in the public domain.
 */

#include <machine/spinlock.h>

int
_atomic_lock(volatile _atomic_lock_t *lock)
{
        _atomic_lock_t old;

        __asm__ volatile (
        ".set   noreorder\n"
        "1:     ll      %0,     0(%1)\n"
        "       sc      %2,     0(%1)\n"
        "       beqz    %2,     1b\n"
        "        addi   %2,     $0, %3\n"
        ".set   reorder\n"
                : "=&r"(old)
                : "r"(lock), "r"(_ATOMIC_LOCK_LOCKED), "i"(_ATOMIC_LOCK_LOCKED)
                : "memory");

        return (old != _ATOMIC_LOCK_UNLOCKED);
}