On Mon, Jan 17, 2000 at 01:18:45PM -0800, David S. Miller wrote:
> > If the intention is to clear bit 31, `&= 0x7fffffff' is the thing which
> > works and is probably more efficient.
>
> Not true on all RISC machines I am familiar with. It's 2 instructions
> either way. On x86 you'll end up using a larger opcode and one of
> x86's most notable performance advantages is it's code density.
Really? On ARM and PA-RISC, it's 1 instruction (BIC and DEPI,
respectively). Do SPARC, MIPS and Alpha really not have a `clear bit'
instruction?
> and `&= (1U<<31)' is more obvious. Using a symbolic constant would be even
> better.
>
> You mean '&= ~(1UL<<31)'
Yes, I do.
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