pub const LEVELS: [f32; 8];Expand description
The eight composite signal voltage levels the 2C02 emits, relative to sync.
Identical to palette_gen’s LEVELS, restated here so the raw-
signal model is self-contained. Indices 0..4 are the “signal low” half of
the chroma square wave for luma levels 0..3; 4..8 are the “signal high”
half. (Bisqwit / nesdev “NTSC video”.)