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Init variable's memory content during comiple-link stage

Amit Alon

Hello,

Some of the variables that my program uses(may contain also big ,multidimensional arrays) have default values, which are used during the code operations and may be modified during the program's runtime.

defining a variables using:

volatile xdata arrayName = [0x01, 0x03, 0x02, 0x04...];
Will case code generation that will occupy more then twice the size of the array. It will generate code are that will hold the array's default values, as well as code that in the beginning of the program startup will copy theses values into the arrays themselves.

On the other side, writing the code as follows:
volatile code arrayName = [0x01, 0x03, 0x02, 0x04...];

(Use of code area, instead of xdata area)

Will cause the array to be generated as part of the code.
There will not be any code line that will init the array into these values, and the init values will be directly located at the generated HEX file, at the place where the array is located, during the compile-link stage.
This is good since it saves time (of the variables init) and more important – it uses much less memory area.
The problem is that defining a variable as code, will prevent it from being modified.

My question:
Is there a way to define variables, that the init value of them will be located in the array's place during the compile-link stage, and that will be modifiable during the program runtime ? can you please tell me the syntax for such a declaration ?

Thanks.
Amit A.

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  • 0 in reply to Amit Alon

    It will generate code are that will hold the array's default values,
    The size needed, where else would you get them from?

    as well as code that in the beginning of the program startup will copy theses values into the arrays themselves.
    That is so little code, that, if that hurt you, you are in deep doo-doo anyhow.

    I think you are trying to make the "'51 PC" (your question and "multi-dimenisional arrays" indicate that this is the case) as so many other mistaken individuals, if that is what you are trying to do, then do not expect '51 tools to help you.
    The '51 is not (and has never been intended to be) a "load before run" device".. It is a "program in permanent storage device", so that is what the tools are made to support, thus they work the way they do.

    As it has been suggested, if you do not like that the tools work in '51 mode, do not use the tools, make your own.

    Erik

Reply
  • 0 in reply to Amit Alon

    It will generate code are that will hold the array's default values,
    The size needed, where else would you get them from?

    as well as code that in the beginning of the program startup will copy theses values into the arrays themselves.
    That is so little code, that, if that hurt you, you are in deep doo-doo anyhow.

    I think you are trying to make the "'51 PC" (your question and "multi-dimenisional arrays" indicate that this is the case) as so many other mistaken individuals, if that is what you are trying to do, then do not expect '51 tools to help you.
    The '51 is not (and has never been intended to be) a "load before run" device".. It is a "program in permanent storage device", so that is what the tools are made to support, thus they work the way they do.

    As it has been suggested, if you do not like that the tools work in '51 mode, do not use the tools, make your own.

    Erik

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