Author: Gerd Isenberg
Date: 12:40:30 04/15/04
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On April 15, 2004 at 04:32:47, Tony Werten wrote: >On April 15, 2004 at 02:09:07, Gerd Isenberg wrote: > >>On April 14, 2004 at 19:34:57, rasjid chan wrote: >> >>>On April 14, 2004 at 15:52:39, Gerd Isenberg wrote: >>> >>>>Hi Rasjid, >>>> >>>>i found a slight improvement in one of your three interesting sliding attack >>>>macros. It replaces the "inbetween"-expression >>>> >>>> isqBit(y)-1 & ~( isqBit(x)-1 | isqBit(x) ) >>>>by >>>> isqBit(y) - isqBit(x+1) >>>>or >>>> isqBit(y) -(isqBit(x)<<1) >>>> >>>>If one subtracts power of two values, greater minus less: >>>> 0100 0000 >>>> -0000 0100 the result is >>>> =0011 1100 a "inner" sequence of ones, except "less" is included. >>>>So we start with next greater bit of "less". >>>> >>>>Couldn't resist to use inlines instead of macros ;-) >>>>(not tested!) >>>> >>> >>>Gerd, >>> >>>How in the world can I see how you see how 0's and 1's interact >>>and extract patterns. I'll first cut and paste and learn later. >>> >>>Thanks >>>Rasjid >>> >> >>There is even a bit more to squeeze out of the functions. Eg. for 0x88 >>coordinates the difference between 0x88 coordinates maps to an unique direction >>index. > >But since the relation between bb and 0x88 is: >0x88 = bb shl 1-(bb and 7), you can also use it for bb. > >Tony Nice trick to save the additional and of the rank ;-) Cheers, Gerd
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