Re: Decoding in bidirectional mode: 4bpp?
>I haven't quite figured out the 4bpp support yet. I think I basically
>understand it: 3 pixels are packed into each 2 bytes you read out of
>the port, the grey coding is the same as the strange 4bpp coding used
>in the unidirectional mode.
>But I'm getting weird results. Scan line 0 is just fine, the top row.
>Scan line 1 is (almost*) entirely useless, though, and scan line 2 is
>also useless. Then scan line 3 is picture data again, and represents
>what'd you'd expect to see on scan line 1. Ie: only every third row is
>valid. To see the effect, compare
Based upon analogies with fax formats, I speculate that you
might need to reset your pixel-unpacker at the beginning of each scan
line, ie, each new scan line might need to start in a new two-byte
frame. This is just a guess.
Craig Milo Rogers