64-bit

This is a discussion on 64-bit within the C++ Programming forums, part of the General Programming Boards category; I'm very concerned about 64-bit programming here and have a question. Are 64-bit processors faster with 64-bit integers or with ...

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    Newbie Crilston's Avatar
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    64-bit

    I'm very concerned about 64-bit programming here and have a question. Are 64-bit processors faster with 64-bit integers or with 32-bit integers?

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    according to some stuff i saw, 64bit processor handle 32bit just
    as well as a 32bit processor, but using 64bit can increase,
    not nessassarily, but can increase the speed of your applciation.
    Last edited by ILoveVectors; 08-11-2005 at 05:24 PM.

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    Super Moderator VirtualAce's Avatar
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    64-bit processors are just that. They fetch 64-bits at a time. Fetching 64 and discarding 32 on a 64 would incur the same performance hit that fetching 32 and discarding 16 does on current processors.

    Lesson to be learned: work with your processor and not against it in your code.

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    so Bubba, they are faster then! :P

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    At the processor / hardware level, 32-bit integers cannot exist on a 64-bit machine. Every time the processor reads or writes, it reads/writes 64 bits. Every memory address holds 64 bits.

    However, I think the operating system performs some data packing. If not, a char would eat-up 8 bytes (7 unused bytes). With all that wasted memory, you would need almost twice as much RAM in a 64-bit system as a 32-bit system.

    If data packing /unpacking is taking place in the background, it will slow-up operations (on smaller data types).

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