Boundary question

This is a discussion on Boundary question within the C Programming forums, part of the General Programming Boards category; In a 32 bit processor if I want to access 8 bit or 16 bit data from RAM, how do ...

  1. #1
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    Boundary question

    In a 32 bit processor if I want to access 8 bit or 16 bit data from RAM, how do processor manage?
    Does it access 4 bytes and disposes remaining three?

    Note: This is regarding ARM processor.

    Please let me know.

  2. #2
    Guest Sebastiani's Avatar
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    Well, it doesn't 'dispose' of the data, you just 'mask off' what you don't need.

    For instance, on intel processors, the register 'eax' can be accessed by:

    [ al ][ ah ]
    [ <-- ax -->]
    [ <-------- eax ---------> ]
    [byte][byte][byte][byte]

    Of course I don't know 'for sure' that it can't access a single byte, just assuming there.
    Code:
    bool fun(bool value)
    {
        return std::pow(std::exp(1), std::complex<float>(0, 1) 
        * std::complex<float>(std::atan(1)*(1 << (value + 2))))
        .real() > 0;
    }

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