[Xc3sprog-users] Use of offset/rlength parameters in xc3sprog

[Joris v. R. <jo...@sr...>]

Hello Uwe,

Thanks for fixing the FTD2XX dependency.

Something else: Last week I tried to program a board with one BIT file 
split over two XCFS devices. I noticed that this no longer works because 
some stuff got mixed up between the bitfile-splitting logic and the 
offset/rlength logic.

I'm trying to fix it, but my problem now is that I don't understand what 
the intended behaviour of the offset/rlength logic is.

For example: "xc3sprog w:sample.bit:64:BIT:32"

Should this take the complete contents of sample.bit (i.e. bytes 0 .. 32 
of the file) and program it into bytes 64 .. 95 of the flash chip?
Or should this take bytes 64 .. 95 from sample.bit and program them into 
bytes 64 .. 95 of the flash chip?

Same question for: "xc3sprog r:sample.bit:64:BIT:32"

This one is especially confusing. It seems that ProgAlgXCF::read takes 
bytes 64 .. 95 and puts them into positions 64 .. 95 of the buffer.
But then BitFile::saveAs writes buffer positions 0 .. 32 to disk.

Also, what is the use case for the offset/rlength feature? Understanding 
that may help me to do the right thing with the multi-PROM logic.

Joris.