Date   : Thu, 11 Nov 2010 09:43:22 +1100
From   : awilliams@... (Alan Williams)
Subject: I suspect an error on this

I suspect that this bit

Detokenising byte 0,1,2,3:
lsb : byte 3 EOR (byte 1 * 16)
msb : byte 2 EOR ((byte 1 AND &30) * 4)

has the lsb and msb labels swapped.

I found using the above format lsb+256*msb did not give the right
results, but swapping them round did.

Which for better or worse comes out looking like this in PHP.

echo ((ord($data{$q+3}) ^  ((ord($data{$q+1})*16) & 0xFF))*256 +
(ord($data{$q+2}) ^  (((ord($data{$q+1}) & 0x30) *4)& 0xFF) ));

I added in a couple of '& 0xFF' to ensure the results stayed 8 bits.

Alan