Lizard music engine

[rainwarrior]

While I was working on the demo for my compression library, I did a little bit of cleanup and organization on the music engine I used for Lizard. Just in case someone feels they need yet another NES music engine, here it is:

https://github.com/bbbradsmith/lizard_music

Notes:

• ca65 (cc65) and python 3 prerequisite
• Subset of Famitracker
  • Volume column supported
  • No DPCM
  • No Hi-Pitch macros (but regular pitch works)
  • Tempo fixed at 150 (use Speed instead)
  • Bxx for looping
  • D00 for variable pattern length
  • F0x for variable speed
  • No other effects supported
• Sound effects on square 1 and/or noise channel
• 22 bytes ZP
• 105 bytes other RAM
• 2152 bytes of code and tables
• ~1800 cycles per frame

[rainwarrior]

I got around to giving this its own home, and a demo framework for testing.