Looks like open-coded be_to_cpu.  GCC produces rather poor code for this. 
be_to_cpu produces asm()s which are ~4 times shorter.

Compile-tested only.

I am not sure whether input can be 64bit-unaligned.
If it indeed can be, replace:

((u64*)(input))[I]  ->  get_unaligned( ((u64*)(input))+I )
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>