f47f04b: hwstub: Add ajt213x lua interface for DSP block
With this you can upload and run code on DSP core in atj213x.
The files can be produced using as2181. You can download this assembler from https://github.com/wodz/as2181 You should use extended mode (-x switch) since DSP core in atj is non standard and uses 24bit operands. PX register has different meaning as well and is used as MSB when loading other registers with immediates (immediate field is 16bit in instruction so to set register to 24bit value you need to store MSB in PX prior to this).
MAC MR is 56bit accordingly.
HIP interface seems to be mapped at standard addresses
(except that regular 218x doesn't have HIP).
The main "innovation" in this patch are two "virtual buttons" for the record switch on YH92x targets. When the switch state changes, a single BUTTON_REC_SW_ON or .._OFF button event will be generated. Thus keymap code can react on switching, but not on the actual state of the switch.
Wherever sensible, the following user scheme is applied:
- use PLAY as confirm button
- use REW button or Long REW to exit
- use REC (YH820) or FFWD (YH92X) as modifier key for button combos