IAR extended keywords

1. Extended keywords: used to control data and pointers

__eeprom is used for EEPROM storage space, controls data storage, controls pointer type and storage
__tinyflash, __flash, __farflash, __hugeflash are used for flash storage space, controls data storage, controls pointer type and storage
__ext_io, __io are used for I/O storage space, controls data storage, controls pointer type and storage
__regvar places a variable in a working register

2. Function extension keywords:

__nearfunc __farfunc is used to control data storage. This group of keywords must be specified when declaring and defining
the function. __interrupt. Keywords control the type of the function. This group of keywords must be specified when declaring and defining the function.
__root. Keywords only control the defined function.

3. Other special keywords:

@ is used to locate the absolute address of the variable. You can also use the #pragma location command
#pragma vector to provide the entry address of the interrupt function.
__root ensures that unused functions or variables can also be included in the target code
__no_init prohibits initialization of variables when the system starts. 
asm, __asm ​​insert assembly code

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The __root keyword ensures that unused functions or variables can also be included in the target code.
The data defined in the __flash space will automatically generate code and embed it into the flash code when the program is compiled. For data that is not used by the program but requires compilation (for example, you can embed your version number, time, etc. in the code), the keyword __root must be added to restrict it.
Example:

#include   
__root __flash unsigned char p @ 0x10 =0x56;  
void main(void)  
{  
  
}

Even if the program does not use the P variable, the compilation will generate this code.  
:020000020000FC  
:1000000016C018951895189518951895189518955F  
:10001000569518951895189518951895189518953A  
:10002000189518951895089500008895FECF0FE94A  
:100030000DBF00E00EBFC0E8D0E003D0F4DFF4DF76  
:06004000F3CF01E008957A  
:0400000300000000F9  
:00000001FF