voltage schedule based on the last value of the previous opcode.
In candidate_opcodes, return the hash of pruned_opcodes as well (since
this is relatively expensive to recompute), so this can be used to
precompute and cache partial results of applying the opcodes.
(indirect) takes 5 cycles not 6! It should be possible to also
accommodate 6502 timings in a followup.
h/t to Scott Duensing who noticed that my sample audio sounded "a tad
slow", which turned out to be due to this 1-cycle difference (which
added up to almost an extra minute playback to an 8-minute song).
Add comments and tidy up the code a bit.
Flesh out README some more.
- we simulate the speaker at full 1-cycle resolution, and
evaluate all possible opcodes that can be scheduled for the
given position in the TCP stream
- this lets us tick the speaker at any cycle interval >=9 (except 10
cycles)
