Re: Question: RC5 assembly code?

Not if it's x86 assembler. On the Pentium each rotate uses 4-5 non-pairable cycles, so rotates are very slow (each rotate is the equivalent of (in the best case) 8-10 normal instructions, so the two rotates in an RC5 round are the equivalent of 16-20 other instructions). According to Intel shifts and rotates have been optimised on the PPro so they're slight faster than on the P5, but I haven't looked at the details yet. I haven't tried to formulate the RC5 core in asm yet (because of the patent - what good is it writing code which noone can use?) but on Intel hardware it's certainly going to be a lot slower than it looks (the much more complex CAST core is faster than just the rotates from the RC5 core). This is kind of unfortunate, because it's a nice algorithm. Peter.
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pgut001@cs.auckland.ac.nz