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    SubjectRe: [PATCH] x86: do not expose CONFIG_BSWAP to userspace
    Harvey Harrison <> writes:

    > Is there a byteswap builtin in gcc? At least AVR32
    > seems to use it, but perhaps it's not generally exposed...perhaps we
    > could ask the gcc-folk?

    Yes, GCC has byteswap builtins on x86 documented as follows:

    -- Built-in Function: int32_t __builtin_bswap32 (int32_t x)
    Returns X with the order of the bytes reversed; for example,
    `0xaabbccdd' becomes `0xddccbbaa'. Byte here always means exactly
    8 bits.

    -- Built-in Function: int64_t __builtin_bswap64 (int64_t x)
    Similar to `__builtin_bswap32', except the argument and return
    types are 64-bit.

    These were only added as of GCC 4.3 though.
    Ben Pfaff

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