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9DE8: Sound FX command 0
Noise.
Input
B Channel index + 1
IX Sound fx data
sound_fx_command_0 9DE8 DEC (IX+$03) Decrement frequency LSB (starts at $00)
9DEB LD A,(IX+$03) Get frequency LSB
9DEE RRA Shift bit 0 into carry
9DEF RET C Return if bit 0 was set
9DF0 LD C,$10
This entry point is used by the routine at sound_fx_command_1_4.
sound_fx_command_0_0 9DF2 LD A,(IX+$04) AAAA00FF (starts at $26)
9DF5 ADD A,C Add 1 to attenuation
9DF6 LD (IX+$04),A Store again
9DF9 AND $F0 Return if attenuation has no rolled over to 0
9DFB RET NZ ...
This entry point is used by the routines at sound_fx_command_3 and sound_fx_command_1_4.
current_sound_fx_done 9DFC LD A,B Channel index + 1
9DFD DEC A Channel index
9DFE JP sound_fx_done Sound fx done
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