Messages in this thread |  | | From | Linus Torvalds <> | Date | Sun, 24 Apr 2022 14:42:28 -0700 | Subject | Re: [PATCH] hex2bin: make the function hex_to_bin constant-time |
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On Sun, Apr 24, 2022 at 2:37 PM Linus Torvalds <torvalds@linux-foundation.org> wrote: > > Finally, for the same reason - please don't use ">> 8". Because I do > not believe that bit 8 is well-defined in your arithmetic. The *sign* > bit will be, but I'm not convinced bit 8 is.
Hmm.. I think it's ok. It can indeed overflow in 'char' and change the sign in bit #7, but I suspect bit #8 is always fine.
Still, If you want to just extend the sign bit, ">> 31" _is_ the obvious thing to use (yeah, yeah, properly "sizeof(int)*8-1" or whatever, you get my drift).
Linus
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