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Antique compression algorithms


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LabVIEW versions prior to 8.0 seem to use 3 compression methods within VI files; these were later replaced by ZLib. The methods are referred to as: Comp, ZComp and UnComp.

Are these from any known library, or NIs own and unstandardized solution?

Is there any kind of stand-alone compressor for these?

 

I don't really need these for my use, but could add support to pyLabview if it is easy to achieve.

 

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'Comp' turned out to be primitive mask-based compression which skips zeros, was easy to implement.

'ZComp' was just the ZLib-based compression, which in later versions is used without being explicitly marked.

'UnComp' is just as the name suggests - uncompressed data. For some reason it follows the same code path as the other two, but the decompressor just copies input to output. So it trolled me into thinking it does something more.

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As your fork's Issues section is disabled, I'm going to ask you here. Have you had a chance to investigate the Fast File Format option, which was introduced starting from LV 2015? It's activated by default for LVLibp and can be turned on for DLL/EXE also in the build properties. If enabled, it produces LEIF resource instead of convenient LVzp, so the whole technique for extracting the resources from EXE's seems to be useless. As some dev's wrote on NI forums, LEIF is more similar to a statically linked PE or ELF file (but neither of those is used actually). There's no any insights on LEIF loader or the binaries format, so I wonder if you dealt with it in some ways.

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