startup_MK64F12.s 文件详解

一、   

                AREA    RESET, DATA, READONLY  
                EXPORT  __Vectors
                EXPORT  __Vectors_End
                EXPORT  __Vectors_Size
                IMPORT  |Image$$ARM_LIB_STACK$$ZI$$Limit|

1、AREA   指令

   The AREA directive instructs the assembler to assemble a new code or data section. Sections are independent, named, indivisible chunks of code or data that are manipulated by the linker.

AREA sectionname{,attr}{,attr}...
1         AREA    RESET, DATA, READONLY             ;分配一个新的数据段 RESET, 属性为只读

2、EXPORT 指令
The EXPORT directive declares a symbol that can be used by the linker to resolve symbol references in separate object and library files.
EXPORT 命令声明一个符号，可由链接器用于解释各个目标和库文件中的符号引用，相当于声明了一个全局变量。 
2                 EXPORT  __Vectors
3                 EXPORT  __Vectors_End
4                 EXPORT  __Vectors_Size                                         ；声明三个符号  __Vectors、__Vectors_End、 __Vectors_Size；
3、IMPORT 指令
将链接器定义的符号导入到汇编器源代码中，请使用IMPORT指令
5         IMPORT  |Image$$ARM_LIB_STACK$$ZI$$Limit|   ;
4、DCD 指令

   The DCD directive allocates one or more words of memory, aligned on four-byte boundaries, and defines the initial runtime contents of the memory.