This is xnu-4903.221.2. See this file in:
// vim:noexpandtab
#ifndef __TYPES_H__
#define __TYPES_H__

#include <stdint.h>
#include <stdbool.h>

typedef	signed char	s8;
typedef	unsigned char	u8;
typedef uint16_t	u16;
typedef int16_t		s16;
typedef uint32_t	u32;
typedef uint64_t	u64;
typedef int32_t		s32;
typedef int64_t		s64;

#if defined(__arm64__) || defined(__x86_64__)
typedef u64	un;
typedef s64	sn;
#else
typedef u32	un;
typedef s32	sn;
#endif

#ifndef __DRT_H__
typedef u32	uint;
#endif

#define volatile_read(atom)		(*((volatile typeof(*(atom)) *)(atom)))
#define volatile_write(atom, value)	(*((volatile typeof(*(atom)) *)(atom)) = value)

#endif