初始化变量并在同一时间指定存储地址：可以吗？ [英] Initializing a variable and specifying the storage address the same time: is it possible?

问题描述

在 Atmel 处理器的 codevision 编译器中，可以指定全局变量的存储地址，例如

In the codevision compiler for Atmel processors, there is a possibility to specify the storage address of a global variable, for example

int a @0x100; // will place the variable at the address 0x100 in RAM

当然，根据标准C，变量可以在声明时初始化

Of course, as per standard C, variables can be initialized upon declaration

int a=42;

但是，我没有发现任何可能性。 int a @ 0x100 = 42 或 int a = 42 @ 0x100; 不工作，它们会导致编译器错误。

However, I did not find any possibility to do them both. int a @0x100 = 42 or int a = 42 @0x100; don't work, they cause compiler errors.

您可能会问为什么这么重要，因为可以简单地使用

You might ask why it is so important to do it, because one could simply have

int a @0x100;

int main()
{
    a = 42;
    //...
}

但是，如果我有变量 EEPROM ，我需要初始化它们，因为这是自动生成带有值的eeprom文件的唯一方法。我不能稍后再分配这些值，因为在这种情况下，它将在程序的每个开始时将值写入eeprom。

However, if I have variables in the EEPROM, I need to initialize them, because this is the only way to automatically generate the eeprom file with the values in it. I can't assign those values later, because in that case it would actually write the values into the eeprom at each start of the program.

推荐答案

看看 CodeVisionAVR 帮助，

如果一个全局变量，必须使用以下过程使用 @ operator 放在特定地址时，必须在声明期间初始化：

"The following procedure must be used if a global variable, placed at a specific address using the @ operator, must be initialized during declaration:

/* the variable will be stored in EEPROM at address 0x10 */

eeprom int abc @0x10;

/* and it will be initialized with the value 123 */ 

eeprom int abc=123; 

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