[Hardware] Notes... The case for an open client
elektron_rc5 at yahoo.ca
Wed Aug 18 13:10:24 EDT 2004
> A CRC could be used instead of a sum for the residual. The CRC
> polynomial X^32+1 would be easy enough to implement in both hardware
> and software and offers the same distributive properties as addition.
> It would be nice if everyone used the same residual function but it's
> not absolutely necessary. The residual is used for local testing and
> random verification.
XORing is probably better than adding (except there's no carrying, so
there's a greater chance that an error in one bit could be negated by a
second error in the same bit). A CRC would be possible, but perhaps too
slow, especially for software cores.
Most CPUs seem to be able to add and XOR at the same speed, though, so
I guess the decision lies with the hardware people.
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