Definition of stm32 data type

In the Keil MDK development environment, for example, an unsigned 32-bit integer data has many ways of representation: 1, unsigned int 32 (standard expression in C language) 2, uint32_t; 3, u32; These three ways all express the same meaning, but why do ST developers make it so confusing? There are many other expressions that may seem strange to you and difficult to understand, such as: _IO int32_t is equivalent to vs32 (this is also unfamiliar to you), but it is also equivalent to volatile int32_t, and it is also equivalent to volatile signed int 32; the last expression is the standard expression in C language, which is confusing enough to confuse beginners.



In fact, ST has so many tricks, just to let developers write fewer symbols when defining data types when writing code, and because of the upgrade of the previous and later versions, so many representation methods will appear in order to be compatible with the old version (mainly V2.0). No matter how it is changed, it is based on standard C. Just look at the following files and you will be OK: core_cm3.h; stm32f10x.h; stdint.h; The functions of each file are as follows:

stdint.h Here is the standard expression of C language

   //Starting from line 36


typedef signed char int8_t; // Standard expression signed char is equivalent to int8_t;
typedef signed short int int16_t;
typedef signed int int32_t; //In a 32-bit environment, int represents 4 bytes 32 bits! !
typedef signed __int64 int64_t;


typedef unsigned char uint8_t;
typedef unsigned short int uint16_t;
typedef unsigned int uint32_t;
typedef unsigned __int64 uint64_t ; typedef





signed char int_least8_t;
typedef signed short int int_least16_t; __int64 int_least64_t;
typedef unsigned char uint_least8_t; typedef unsigned short int uint_least16_t; typedef unsigned int uint_least32_t; _t; typedef unsigned __int64 int_fast64_t; typedef unsigned int uint_fast8_t; typedef unsigned int uint_fast16_t; typedef unsigned int uint_fast32_t; typedef unsigned __int64 uint_fast64_t; typedef signed int intptr_t; typedef unsigned int uintptr_t; typedef signed __int64 intmax_t; typedef unsigned __int64 uintmax_t; The core_cm3.h file mainly makes type extensions for dynamic and static variable modifiers #ifdef __cplusplus   #define __I volatile             #else   #define __I volatile const       #endif #define __O volatile             #define __IO volatile stm32f10x.h This file is mainly for compatibility with old versions typedef int32_t s32; typedef int16_t s16; typedef int8_t s8; typedef const int32_t  sc32;  typedef const int16_t sc16 ; typedef const int8_t sc8;   typedef __IO int32_t vs32; __I int16_t vsc16  ;  typedef __I int8_t vsc8;  






























































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

typedef const uint32_t uc32; 
typedef const uint16_t uc16; 
typedef const uint8_t uc8;  

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

typedef __I uint32_t vuc32; 
typedef __I uint16_t vuc16; 
typedef __I uint8_t vuc8;