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locating arguments

Kaoru K

Hello,


I would like to know how the keil compiler locate the arguments of a function.

1) it pass it via the stack?
2) it declares a places in the memory space, and in this case how he choose the memory space that it will use?


Thank You
Kaoru

Parents
  • 0 in reply to Andy Neil

    I have 4 function of the type

    void funct(unsigned char)

    three of them are not optimized and the compiler put the parameters in the external memory. And only one of them is optimized by passing parameter in the register.
    For the three first functions, at the compilation, it will change the place of the parameter.
    Am i correct?
    Is there a mean to locate the parameter somewhere in the xdata?

    As those four functions are a part of a same level. i want them to be similar in the way of passing parameters. Like this i will have the same technology use for a same level.

    Do you think it is possible to do that by passing parameters in those functions?

    thank you
    Kaoru

Reply
  • 0 in reply to Andy Neil

    I have 4 function of the type

    void funct(unsigned char)

    three of them are not optimized and the compiler put the parameters in the external memory. And only one of them is optimized by passing parameter in the register.
    For the three first functions, at the compilation, it will change the place of the parameter.
    Am i correct?
    Is there a mean to locate the parameter somewhere in the xdata?

    As those four functions are a part of a same level. i want them to be similar in the way of passing parameters. Like this i will have the same technology use for a same level.

    Do you think it is possible to do that by passing parameters in those functions?

    thank you
    Kaoru

Children
  • 0 in reply to Kaoru K

    Are some of them "leaf" functions, and some not?

  • 0 in reply to Kaoru K

    Use NOREGPARMS and the compiler puts ALL ARGUMENTS IN MEMORY and NONE IN REGISTERS.

    Jon

  • 0 in reply to Jon Ward

    I am sorry I don't understand what is "leaf"...
    The only difference between the function is the moment that i use the parameter. In the function that is compiled by passing parameter in the register, the variable is used just after the declarations. But for the other the variable is used in the middle of the function.

    the NOREGPARAMS is a good idea but as i want that the compilation is always the same, i have to locate those arguments. Can you tell me if it is possible? I tried to do it without success.

    Thank you
    Kaoru

  • 0 in reply to Kaoru K

    i have to locate those arguments. Can you tell me if it is possible?

    If I understand you, you want to locate the arguments to several functions to the same address. For example:

    int func_a (int arg_a, int arg_b, int arg_c);
int func_b (int arg_a, int arg_b, int arg_c);
int func_c (int arg_a, int arg_b, int arg_c);

    func_a, func_b, and func_c should all have their arguments stored at the same address x.

    If that's the case, there is no way to automatically do that with the compiler.

    You can, however, do it manually with little or no overhead. Simply declare global variables that represent the function arguments. For example:

    int arg_a, arg_b, arg_c;

int func_a (void);
int func_b (void);
int func_c (void);

    Then, you can "load" the arguments externally and you can access the arguments inside func_a, func_b, and func_c.

    Jon