typedef unsigned char u8;
typedef unsigned short u16;
typedef unsigned int u32;
typedef unsigned long long u64;
typedef signed char s8;
typedef signed short s16;
typedef signed int s32;
typedef signed long long s64;
typedef _Bool bool;

# define CC_SET(c) "\n\t/* output condition code " #c "*/\n"
# define CC_OUT(c) "=@cc" #c

#define likely(x)     __builtin_expect(!!(x), 1)
#define unlikely(x)   __builtin_expect(!!(x), 0)

extern void __cmpxchg_wrong_size(void);

#define __raw_cmpxchg(ptr, old, new, size, lock)			\
({									\
	__typeof__(*(ptr)) __ret;					\
	__typeof__(*(ptr)) __old = (old);				\
	__typeof__(*(ptr)) __new = (new);				\
	switch (size) {							\
	case 1:						\
	{								\
		volatile u8 *__ptr = (volatile u8 *)(ptr);		\
		asm volatile(lock "cmpxchgb %2,%1"			\
			     : "=a" (__ret), "+m" (*__ptr)		\
			     : "q" (__new), "0" (__old)			\
			     : "memory");				\
		break;							\
	}								\
	case 2:						\
	{								\
		volatile u16 *__ptr = (volatile u16 *)(ptr);		\
		asm volatile(lock "cmpxchgw %2,%1"			\
			     : "=a" (__ret), "+m" (*__ptr)		\
			     : "r" (__new), "0" (__old)			\
			     : "memory");				\
		break;							\
	}								\
	case 4:						\
	{								\
		volatile u32 *__ptr = (volatile u32 *)(ptr);		\
		asm volatile(lock "cmpxchgl %2,%1"			\
			     : "=a" (__ret), "+m" (*__ptr)		\
			     : "r" (__new), "0" (__old)			\
			     : "memory");				\
		break;							\
	}								\
	case 8:						\
	{								\
		volatile u64 *__ptr = (volatile u64 *)(ptr);		\
		asm volatile(lock "cmpxchgq %2,%1"			\
			     : "=a" (__ret), "+m" (*__ptr)		\
			     : "r" (__new), "0" (__old)			\
			     : "memory");				\
		break;							\
	}								\
	default:							\
		__cmpxchg_wrong_size();					\
	}								\
	__ret;								\
})

#define __cmpxchg(ptr, old, new, size)					\
	__raw_cmpxchg((ptr), (old), (new), (size), LOCK_PREFIX)

#define cmpxchg(ptr, old, new)						\
	__cmpxchg(ptr, old, new, sizeof(*(ptr)))

#define __raw_try_cmpxchg(_ptr, _pold, _new, size, lock)		\
({									\
	bool success;							\
	__typeof__(_ptr) _old = (__typeof__(_ptr))(_pold);		\
	__typeof__(*(_ptr)) __old = *_old;				\
	__typeof__(*(_ptr)) __new = (_new);				\
	switch (size) {							\
	case 1:						\
	{								\
		volatile u8 *__ptr = (volatile u8 *)(_ptr);		\
		asm volatile(lock "cmpxchgb %[new], %[ptr]"		\
			     CC_SET(z)					\
			     : CC_OUT(z) (success),			\
			       [ptr] "+m" (*__ptr),			\
			       [old] "+a" (__old)			\
			     : [new] "q" (__new)			\
			     : "memory");				\
		break;							\
	}								\
	case 2:						\
	{								\
		volatile u16 *__ptr = (volatile u16 *)(_ptr);		\
		asm volatile(lock "cmpxchgw %[new], %[ptr]"		\
			     CC_SET(z)					\
			     : CC_OUT(z) (success),			\
			       [ptr] "+m" (*__ptr),			\
			       [old] "+a" (__old)			\
			     : [new] "r" (__new)			\
			     : "memory");				\
		break;							\
	}								\
	case 4:						\
	{								\
		volatile u32 *__ptr = (volatile u32 *)(_ptr);		\
		asm volatile(lock "cmpxchgl %[new], %[ptr]"		\
			     CC_SET(z)					\
			     : CC_OUT(z) (success),			\
			       [ptr] "+m" (*__ptr),			\
			       [old] "+a" (__old)			\
			     : [new] "r" (__new)			\
			     : "memory");				\
		break;							\
	}								\
	case 8:						\
	{								\
		volatile u64 *__ptr = (volatile u64 *)(_ptr);		\
		asm volatile(lock "cmpxchgq %[new], %[ptr]"		\
			     CC_SET(z)					\
			     : CC_OUT(z) (success),			\
			       [ptr] "+m" (*__ptr),			\
			       [old] "+a" (__old)			\
			     : [new] "r" (__new)			\
			     : "memory");				\
		break;							\
	}								\
	default:							\
		__cmpxchg_wrong_size();					\
	}								\
	if (unlikely(!success))						\
		*_old = __old;						\
	likely(success);						\
})

#define LOCK_PREFIX "lock; "

#define __try_cmpxchg(ptr, pold, new, size)				\
	__raw_try_cmpxchg((ptr), (pold), (new), (size), LOCK_PREFIX)

#define try_cmpxchg(ptr, pold, new)					\
	__try_cmpxchg((ptr), (pold), (new), sizeof(*(ptr)))

#define READ_ONCE(x) (*(volatile typeof(x) *)(&x))

int __down_read_trylock1(unsigned long *l)
{
	long tmp;

	while ((tmp = READ_ONCE(*l)) >= 0) {
		if (tmp == cmpxchg(l, tmp, tmp + 1))
			return 1;
	}

	return 0;
}

int __down_read_trylock2(unsigned long *l)
{
	long tmp = READ_ONCE(*l);

	while (tmp >= 0) {
		if (try_cmpxchg(l, &tmp, tmp + 1))
			return 1;
	}

	return 0;
}

int __down_read_trylock3(unsigned long *l)
{
	long new, old = READ_ONCE(*l);

	for (;;) {
		new = old + 1;
		if (new <= 0)
			return 0;
		if (try_cmpxchg(l, &old, new))
			return 1;
	}
}