pointer specific

This is a discussion on pointer specific within the C Programming forums, part of the General Programming Boards category; how to wrap pointers? do i need to align pointer in memory (by padding or something)? i have array table ...

  1. #1
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    Jan 2012
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    pointer specific [solved]

    how to wrap pointers?

    do i need to align pointer in memory (by padding or something)?

    i have array table of chars.
    example char array[65536).

    making:
    char *ptr = array;

    //in some loop (this dont work)
    *ptr += some_number;
    *ptr &= 0xffff; //modulu 65535+1

    //this work, but no pointer used
    value = array[index++ & 0xffff];

    ideas for pointer wrapping?
    Last edited by c coder; 06-11-2012 at 07:38 AM.

  2. #2
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    > modulu 65535+1
    That trick only works when you're trying to modulus by a power of two, then it's that number minus one.

    > do i need to align pointer in memory
    No. There's hardly ever a reason to force a pointer to alignment, unless it's for the purpose of optimization (usually only applicable in assembly). Otherwise, the computer will take care of this with caching and other mechanisms designed to keep access aligned.

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