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munshkr / picopico

:headphones: ATtiny85-based chiptune player
GNU General Public License v3.0
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Implement a fast multiplication routine #1

Closed munshkr closed 7 years ago

munshkr commented 7 years ago

The ATtiny85 has no hardware multiplication support, needed for the envelope generator.

Try out some of these. There's not much room for big tables, but for 8x8 mult only 512 bytes of progmem are needed (256 16bit values).

http://stackoverflow.com/questions/29935050/tinyavr-best-known-multiplication-routines-for-8-bit-and-16-bit-factors

munshkr commented 7 years ago

Another alternative is to constrain the envelope generator to 16 values (like the NES APU), which would require 4bit mult...?

munshkr commented 7 years ago

Not needed right now.