[CDG5] Random questions

Elliot Nunn elliotnunn at fastmail.com
Wed Dec 12 11:20:59 AWST 2018


Cool! The code I’ve written allows compression algorithms to be described by an arbitrary string. ‘GreggyBitsBitmap’ would work?

> On 12 Dec 2018, at 10:17 am, Max Poliakovski <maximumspatium at googlemail.com> wrote:
> 
> From my understanding, the bit-mapped compression allows for a bigger alphabet than a 256 words table can hold. This means a greater flexibility but a worse compression ratio. Instead of replacing each word with a table index (which ideally yields a 2:1 compression), we add an extra byte for each group of eight words indicating if a particular word is coded "as is" (plain text) or as table index. The compression ratio in this case is left as an exercise to the reader.
> 
> Non-bitmapped compression assumes that all words will be in the lookup table that, in turn, seems to be pretty small for large resources. This therefore makes me think that the bitmapped compression is used more frequently than the non-bitmapped one.
> 
> My code doesn't currently support automatic mode/table switching but relies on these parameters being supplied by user. Because we're speaking about small changes, recompressing a particular resource under control of the original parameters looks like the easiest solution...
> 
> 
>> Am Mi., 12. Dez. 2018 um 00:25 Uhr schrieb Elliot Nunn <elliotnunn at fastmail.com>:
>> Neat!
>> 
>> What is the significance of isBitMapped?
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