STM32系统头文件之数据类型定义u8 u16哪里来的

初学STM32编程时，经常见到数据类型定义的符号：u8、u16等，51都是自己定义数据类型的简写符号，STM32是哪里定义的呢？今天没事就看了看系统头文件，数据类型的定义在其中的3个头文件里：

（1）stdint.h（摘取定义部分）

/*
 * 'signed' is redundant below, except for 'signed char' and if
 * the typedef is used to declare a bitfield.
 */


    /* 7.18.1.1 */


    /* exact-width signed integer types */
typedef   signed          char int8_t;
typedef   signed short     int int16_t;
typedef   signed           int int32_t;
typedef   signed       __INT64 int64_t;


    /* exact-width unsigned integer types */
typedef unsigned          char uint8_t;
typedef unsigned short     int uint16_t;
typedef unsigned           int uint32_t;
typedef unsigned       __INT64 uint64_t;


    /* 7.18.1.2 */


    /* smallest type of at least n bits */
    /* minimum-width signed integer types */
typedef   signed          char int_least8_t;
typedef   signed short     int int_least16_t;
typedef   signed           int int_least32_t;
typedef   signed       __INT64 int_least64_t;


    /* minimum-width unsigned integer types */
typedef unsigned          char uint_least8_t;
typedef unsigned short     int uint_least16_t;
typedef unsigned           int uint_least32_t;
typedef unsigned       __INT64 uint_least64_t;


    /* 7.18.1.3 */


    /* fastest minimum-width signed integer types */
typedef   signed           int int_fast8_t;
typedef   signed           int int_fast16_t;
typedef   signed           int int_fast32_t;
typedef   signed       __INT64 int_fast64_t;


    /* fastest minimum-width unsigned integer types */
typedef unsigned           int uint_fast8_t;
typedef unsigned           int uint_fast16_t;
typedef unsigned           int uint_fast32_t;
typedef unsigned       __INT64 uint_fast64_t;


    /* 7.18.1.4 integer types capable of holding object pointers */
#if __sizeof_ptr == 8
typedef   signed       __INT64 intptr_t;
typedef unsigned       __INT64 uintptr_t;
#else
typedef   signed           int intptr_t;
typedef unsigned           int uintptr_t;
#endif


    /* 7.18.1.5 greatest-width integer types */
typedef   signed     __LONGLONG intmax_t;
typedef unsigned     __LONGLONG uintmax_t;

（2）STM32F10x.h（摘取定义部分）

/*!< STM32F10x Standard Peripheral Library old types (maintained for legacy purpose) */
typedef int32_t  s32;
typedef int16_t s16;
typedef int8_t  s8;


typedef const int32_t sc32;  /*!< Read Only */
typedef const int16_t sc16;  /*!< Read Only */
typedef const int8_t sc8;   /*!< Read Only */


typedef __IO int32_t  vs32;
typedef __IO int16_t  vs16;
typedef __IO int8_t   vs8;


typedef __I int32_t vsc32;  /*!< Read Only */
typedef __I int16_t vsc16;  /*!< Read Only */
typedef __I int8_t vsc8;   /*!< Read Only */


typedef uint32_t  u32;
typedef uint16_t u16;
typedef uint8_t  u8;


typedef const uint32_t uc32;  /*!< Read Only */
typedef const uint16_t uc16;  /*!< Read Only */
typedef const uint8_t uc8;   /*!< Read Only */


typedef __IO uint32_t  vu32;
typedef __IO uint16_t vu16;
typedef __IO uint8_t  vu8;


typedef __I uint32_t vuc32;  /*!< Read Only */
typedef __I uint16_t vuc16;  /*!< Read Only */
typedef __I uint8_t vuc8;   /*!< Read Only */

（3）core_cm3.h（摘取部分）

/**
 * IO definitions
 *
 * define access restrictions to peripheral registers
 */

#ifdef __cplusplus
  #define     __I     volatile                /*!< defines 'read only' permissions      */
#else
  #define     __I     volatile const          /*!< defines 'read only' permissions      */
#endif
#define     __O     volatile                  /*!< defines 'write only' permissions     */
#define     __IO    volatile                  /*!< defines 'read / write' permissions   */