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From C, inline assembly LJMP to Numerical Address

Ted Dubroff

How do I perform a long jump to a numerical address from my C code?
I'm pretty sure I have to do this with inline assembly - however that
seems complicated for C51. I figured in C I could do this:

typedef void (*jmpPtr)(void);
jmpPtr jmp;

...

unsigned int address = 0x4000U;
jmp = (jmpPtr) address;
(*jmp)();

Except for the call differences, I think this would be the same as doing
a jump to the numerical address? Keil, is this correct?

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  • 0 in reply to Ted Dubroff

    Just to make it more readable I suppose.

    I'm not sure I'd agree that 5 lines is more readable than 2. To each their own.

    Setjmp() and longjmp() save the state from one code point to
    another and doesn't allow for specifying an address.

    Good point. If you don't like the LCALL then you'll have to use some assembler I'm afraid. How bad is the LCALL implementation for you?

    - Mark

Reply
  • 0 in reply to Ted Dubroff

    Just to make it more readable I suppose.

    I'm not sure I'd agree that 5 lines is more readable than 2. To each their own.

    Setjmp() and longjmp() save the state from one code point to
    another and doesn't allow for specifying an address.

    Good point. If you don't like the LCALL then you'll have to use some assembler I'm afraid. How bad is the LCALL implementation for you?

    - Mark

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