Space Raiders: Routine at 31303

Sets 2 rows of attributes to an INK colour, starting with the row in _NEXT_ALIEN_ROW_TO_DRAW. The colour comes from a table indexed by the value at _ALIEN_BAND_ARG.

As the aliens move down the screen the bands of yellow, green, green, red, red need to move down with them. This sets the colour bands for one row of aliens

The alien band to set is passed in via _ALIEN_BAND_ARG and provides the colour: top row (0) is yellow, row 1 is green, etc

_NEXT_ALIEN_ROW_TO_DRAW is cy; the cy is the attribute row to start at. _ALIEN_BAND_ARG contains band to set colour, 0 being top alien row

Called from the routine at print_alien_row

Sets 2 rows of attributes to an INK colour, starting with the row in _NEXT_ALIEN_ROW_TO_DRAW. The colour comes from a table indexed by the value at _ALIEN_BAND_ARG. As the aliens move down the screen the bands of yellow, green, green, red, red need to move down with them. This sets the colour bands for one row of aliens The alien band to set is passed in via _ALIEN_BAND_ARG and provides the colour: top row (0) is yellow, row 1 is green, etc _NEXT_ALIEN_ROW_TO_DRAW is cy; the cy is the attribute row to start at. _ALIEN_BAND_ARG contains band to set colour, 0 being top alien row Called from the routine at print_alien_row
set_alien_colour_band	31303	LD BC,(_NEXT_ALIEN_ROW_TO_DRAW)	cy from here goes into B
	31307	LD C,0	cx is 0, start of row
	31309	LD HL,_ALIEN_COLOUR_BANDS	Colour bands table
	31312	LD A,(_ALIEN_BAND_ARG)	Alien row to colour, 0 to 4 (top to bottom)
	31315	ADD A,L	Find table entry
	31316	LD L,A
	31317	JR NC,set_alien_colour_band_0
	31319	INC H
set_alien_colour_band_0	31320	LD A,(HL)	Pick up INK colour from (HL)
	31321	LD E,A	E is INK colour
	31322	LD D,64	2 full rows
	31324	JP set_attributes_xy_n	Set INK colour of 64 cells from B,C