Reduce the size of huffman decode table

[ariaandika]

The type of huffman decode table is [[(usize, u8, u8); 16]; 256], where the usize is an index to the next entry within that table. Because the length of the table is exactly 256, wouldnt be storing the index as u8 make the table size significantly smaller ?

[seanmonstar]

Nice catch! It does seem like we could make that optimization, as long we have some tests to catch if we ever changed how the states were stored (and could need a longer table).

[ariaandika]

I dont think tests would be necessary, because the states is constant literal. So if one need a longer table, the compiler will catch that as integer overflow.

Besides, the decode table is generated from huffman code in rfc7541, so a change is very unlikely.

[seanmonstar]

True. Would you like to submit a PR making this change?

[ariaandika]

Sure