typedef struct fairlock {
	u8	curr;
	u8	ticket;
} fairlock_t;

static inline init_fairlock(fairlock_t *lock)
{
	memset(lock,0,sizeof(*lock));
}

/*
 * spin lock fairly
 */
static inline void fair_lock(fairlock_t *lock)
{
	u8 number = 1;

	__asm__ __volatile__(
		"# beginning fair_lock\n\t"
LOCK_PREFIX	"  xaddb     %b2,%1\n\t"	/* number = lock->ticket; lock->ticket++; */
		"1:\n\t"
		"  cmpb	     %b2,%0\n\t"
		"  jne       2f\n\t"		/* jump if number!=lock->curr */
		LOCK_SECTION_START("")
		"2:\n\t"
		"  rep; nop\n\t"
		"  jmp       1b\n"
		LOCK_SECTION_END
		"# ending fair_lock\n\t"
		: "=m"(lock->curr), "=m"(lock->ticket), "=r"(number)
		: "r"(lock), "m"(lock->curr), "m"(lock->ticket), "2"(number)
		: "memory", "cc");
}

/*
 * spin trylock fairly
 */
static inline void fair_trylock(fairlock_t *lock)
{
	u32 tmp;

	__asm__ __volatile__(
		"# beginning fair_trylock\n\t"
		"  movw      (%3),%%ax\n\t"	/* AL=curr, AH=ticket */
		"1:\n\t"
		"  cmpb      %%al,%%ah\n\t"
		"  je        3f\n\t"		/* jump if maybe we can get it */
		"2:\n\t"
		LOCK_SECTION_START("")
		"3:\n\t"
		"  leaw      1(%ax),%w2\n\t"	/* [propose] ticket=ticket+1 */
LOCK_PREFIX	"  cmpxchgw  %w2,(%3)\n\t"
		"  je        3b\n\t"		/* jump if worked */
		"  rep; nop\n\t"		/* didn't work; AL & AH have been updated */
		"  jmp       1b\n"
		LOCK_SECTION_END
		"# ending fair_trylock\n\t"
		: "=m"(lock->curr), "=m"(lock->ticket), "=$r"(tmp)
		: "r"(lock), "m"(lock->curr), "m"(lock->ticket)
		: "memory", "cc", "eax");
}

/*
 * spin unlock fairly
 */
static inline void fair_unlock(fairlock_t *lock)
{
	u8 number;

	__asm__ __volatile__(
		"# beginning fair_unlock\n\t"
LOCK_PREFIX	"  incb      %1\n\t"		/* lock->curr++; */
		"# ending fair_unlock\n\t"
		: "=m"(lock->curr)
		: "r"(lock), "m"(lock->curr)
		: "memory", "cc");
}