uint8_t / uint16_t / uint32_t /u

按照posix标准，一般整形对应的*_t类型为:

1字节     uint8_t
2字节     uint16_t
4字节     uint32_t
8字节     uint64_t

#ifndef __int8_t_defined  
# define __int8_t_defined  
typedef signed char             int8_t;   
typedef short int               int16_t;  
typedef int                     int32_t;  
# if __WORDSIZE == 64  
typedef long int                int64_t;  
# else  
__extension__  
typedef long long int           int64_t;  
# endif  
#endif  
  
  
typedef unsigned char           uint8_t;  
typedef unsigned short int      uint16_t;  
#ifndef __uint32_t_defined  
typedef unsigned int            uint32_t;  
# define __uint32_t_defined  
#endif  
#if __WORDSIZE == 64  
typedef unsigned long int       uint64_t;  
#else  
__extension__  
typedef unsigned long long int  uint64_t;  
#endif  

原文： https://blog.csdn.net/kiddy19850221/article/details/6655066