Is it possible to increase the size of the sliding window beyond 32KB for zlib?

Question

I would like to increase the size of the sliding window for zlib beyond the maximum 32KB (I would like to match the window size to the length of the string that I am trying to compress). This is because I want to make sure that if a match exist it'll be found. Can this be done easily? Or are there subtleties in the implementation that I should consider?

Answer 1

It would require a redesign of the deflate format, which inherently only allows distances of 32768 or less, and a rewrite of the deflate code in zlib.

The redesign of the deflate format was already done once, resulting in deflate64 which permits distances up to 65536 (maybe not enough for you?), which the zlib code could in principle be rewritten to accommodate.

Alternatively, you can use other LZ compressors already written and tested with larger windows (often much larger windows), such as lzma or brotli.