This moves all RX packet processing into interrupt context, removing the queueing bottleneck that previous firmwares experienced. Before this change, we could handle at most ~3 packets before they would start NAK'ing due to lack of buffer space until the next main loop iteration pulled additional packets into the fbNew buffer. Now packets can immediately go into fbNew unless there's a pending frame finalization. This vastly improves the efficiency of the USB protocol, and we need far fewer NAKs.

Now the firmware config flags actually select between several different inner-loops. This will be useful in the future if we want to support different configurations with runtime config options, and right now it's useful for side-by-side comparisons with the various config options.

This makes it easier to move around for future optimizations, and it already gains us a few FPS by allowing the compiler to optimize a little better

This makes the mapping from 16-bit color to LUT entry straightforward, while still fully defining the entire range from 0x0000 through 0xFFFF. This fixes an edge case where colors greater than 0xFF00 would wrap past the end of the R/G LUTs onto the next color channel.

The first frame after a new keyframe arrives would be using the wrong interpolation coefficient.

This amazingly helps quite a lot! The idle time between frames is down from 0.8ms to 0.66ms now.

This reverts commit 07106959.

This reverts commit f5e7cc2e.

This actually makes us slightly slower, due to increased register pressure, but I think if I can alleviate that we'll see a speedup.

Woo!

This reverts commit 05116f49.

Blah, this increased our delay from 1ms to 1.2ms. Not sure why it seemed to help at first.

Almost fast enough.. just 1.3ms more to shave off per frame.