Messages in this thread | | | From | Ben Pfaff <> | Subject | Re: [PATCH] x86: do not expose CONFIG_BSWAP to userspace | Date | Wed, 28 Jan 2009 15:04:07 -0800 |
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Harvey Harrison <harvey.harrison@gmail.com> 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 http://benpfaff.org
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