[sword-devel] How to compress large commentaries?

Chris Little chrislit at crosswire.org
Wed Nov 20 18:16:24 MST 2013

Yes, zText/zCom entry size is held as an unsigned short, so can be of 
length <2^16.

On 11/12/2013 7:58 AM, John Austin wrote:
> I've got a large Russian commentary which is nearly 30MB. It has some
> very long introductions and commentary "verses" which are greater than
> 64KB in length. These are easily handled with the RawCom4 driver. But
> when I use mod2zmod to compress the module, these long entries get
> truncated (also without warning).
> The zVerse class for reading compressed Bible and commentary modules
> uses a 2 byte integer to represent verse size. This seems to truncate
> all commentary entries (verses) which are greater than 64KB in length.

RawText4 & RawCom4 were only added in 2007 since there wasn't previously 
seen to be a need for such long Bible/commentary verse entries. The 
contributor of RawText4 & RawCom4 apparently did not submit a 
corresponding zText4 or zCom4 class.

> So is there another way I'm not seeing to compress this commentary? If
> there is no way at present, can we come up with a way to do this for the
> future? Maybe a zVerse4 could be added? Or some other way? Of all the
> module types, commentaries can really benefit from compression since
> they can be so huge.

zText4 & zCom4 could be added without much effort, but doing so would 
obviously require a new point release, at a minimum. I don't think 
adding new classes causes any problems for us with respect to our 
ABI/API compatibility stability policies (not that I'm sure we have even 
defined any), but would appreciate some confirmation from someone who is 
more familiar with that.


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