alt Hacker NewsYou can have a single 3x256=768-byte table -- just multiply the input byte by 3 to get the offset into the table, and read out the 3 trits (1 trit per byte) beginning at that offset.
ETA: If you're prepared to waste a byte per entry so that entries are 4 bytes wide, on x86 you can use effective address calculation to do the multiplication for you, letting you decode 3 trits in 1 CPU instruction:
MOV EAX,[RBX+RCX*4]
There are 5 trits.
In any case, if there were 3 trits, I'm not sure what the practical difference between a single table you describe and 3 different 256 byte tables, again depending on the architecture.
Yes a single table would have better cache effects for a single read, but presumably? you're doing a lot of reads in an unpacking phase.