weight of diffs that persist across multiple frames.
For each frame, zero out update priority of bytes that no longer have
a pending diff, and add the edit distance of the remaining diffs.
Zero these out as opcodes are retired.
Replace hamming distance with Damerau-Levenshtein distance of the
encoded pixel colours in the byte, e.g. 0x2A --> GGG0 (taking into
account the half-pixel)
This has a couple of benefits over hamming distance of the bit patterns:
- transposed pixels are weighted less (edit distance 1, not 2+ for
Hamming)
- coloured pixels are weighted equally as white pixels (not half as
much)
- weighting changes in palette bit that flip multiple pixel colours
While I'm here, the RLE opcode should emit run_length - 1 so that we
can encode runs of 256 bytes.
bytemap, (page,offset) memory map)
- add a FlatMemoryMap that is a linear 8K array
- add converter methods and default constructors that allow converting
between them
- use MemoryMap as the central representation used by the video encoder
opcodes until the cycle budget for the frame is exhausted.
Output stream is also now aware of TCP framing, and schedules an ACK
opcode every 2048 output bytes to instruct the client to perform
TCP ACK and buffer management.
Fixes several serious bugs in RLE encoding, including:
- we were emitting the RLE opcode with the next content byte after the
run completed!
- we were looking at the wrong field for the start offset!
- handle the case where the entire page is a single run
- stop trying to allow accumulating error when RLE -- this does not
respect the Apple II colour encoding, i.e. may introduce colour
fringing.
- also because of this we're unlikely to actually be able to find
many runs because odd and even columns are encoded differently. In
a followup we should start encoding odd and even columns separately
Optimize after profiling -- encoder is now about 2x faster
Add tests.
