Robotron: 2084: Routine at 62880

62880: Advance Intro Colour Cycle

Used by the routine at Attract_Mode_Loop. Advances the intro screen colour cycling effect by one step. Reads source and replacement colours from Intro_Colour_Cycle_Table via the pointer at Intro_Colour_Cycle_Pointer, then scans all 768 attribute cells and replaces every cell matching the source colour with the replacement.
Advance_Intro_Colour_Cycle	62880	LD HL,(62878)	Load the colour cycle pointer and read the source colour.
	62883	LD D,(HL)
	62884	INC HL
Advance_Intro_Colour_Cycle_Read	62885	LD A,(HL)	Read the next cycle entry; jump to Advance_Intro_Colour_Cycle_Apply if not the end.
	62886	CP 255
	62888	JR NZ,Advance_Intro_Colour_Cycle_Apply
	62890	LD HL,62903	Reset the colour cycle pointer to the table start.
	62893	JR Advance_Intro_Colour_Cycle_Read	Reset the colour cycle pointer to the table start.
Advance_Intro_Colour_Cycle_Apply	62895	LD E,A	Set up the replacement and source colours.
	62896	LD A,D	Set up the replacement and source colours.
	62897	LD (62878),HL	Save the updated colour cycle pointer.
	62900	JP Advance_Colour_Cycle_Scan	Scan the attribute area and apply the colour swap.