I'm sure it's just me, but I would find it alot easier to just remember a
"flip table". Perhaps it's just my math...
Francisco.
"Roger Dellaca" <[EMAIL PROTECTED]> escribió en el mensaje de noticias
[EMAIL PROTECTED]
> I have found a way to memorize the Token-to-ethernet (& back) address
conversion - if you like it, great, if not, ignore it. You probably won't
like it unless you really liked math in school.
>
> So we know that you have to bit-flip each byte, and we know that if each
byte is written as 2 hex digits, then you can swap each pair of hex digits
in the byte & flip each hex digit (example: flipping 7D as a byte is binary
0111 1101 flipped to 1011 1110 which is BE - doing it by the hex digit is 7D
swapped to D7, D flips to B & 7 flips to E so it's BE). Now how do you
memorize the flip for each hex digit?
>
> THE 1st SIX PRIME NUMBERS (2,3,5,7,11,13) !!!
>
> 1st - powers of 2: they are 1,2,4,8 (0 is not a power of 2, it's a
multiple; & 16 is higher than a single hex digit) they flip with each other
in high-low pairs, so 1 & 8 flip to each other, & 2 & 4 flip to each other.
>
> 2nd - multiples of 3,5,7 (and the 4 magic flips): the multiples of 3 are
0,3,6,9,C (12), and F (15). 0,6,9 & F are the magic flips - they are the
same when flipped( Remember 4 magic flips for a 4-bit hex digit). The others
are 3 & C which flip to each other. The multiples of 5 are 5 and A (I
skipped 0 & F because we already touched them with the 3's), and they flip
to each other. The multiples of 7 are 7 & E, which flip to each other.
>
> 3rd & finally - B (11) and D (13) are all that are left & they flip to
each other.
>
> There!
>
> (By the way, for anyone that hasn't fallen asleep yet, the reason for 4
magic flips isn't because of the 4 digits in a hex number - that's just a
mnemonic. Technically, a magic flip is where you divide the number of
digits in half & each half is a mirror image, so 4 bits divided by 2 is 2,
and there are 4 possibilities in a 2-bit number.)
>
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