Chase H.Q.: Routine at 8EE7

8EE7: Draw the smash bar

Used by the routine at main_loop.
draw_smash_bar	8EE7	LD A,($A22E)	Return if the perp has not yet been sighted
	8EEA	AND A
	8EEB	RET Z
	8EEC	LD A,($A230)	Return if perp_caught_stage is >= 3 (car has stopped)
	8EEF	CP $03
	8EF1	RET NC
	8EF2	LD HL,$F7A2	Back buffer address of bottom of bar
	8EF5	LD DE,$0F10	D = 15 = mask, E = 16 = row stride
Draws bottom two rows
	8EF8	LD B,$02	2 rows
	8EFA	CALL draw_smash_bar_solid_bit	Call draw_smash_bar_solid_bit
	8EFD	LD A,($A233)	Get smash_counter
	8F00	AND A	Jump straight to drawing solid if it's zero (whole bar solid)
	8F01	JR Z,draw_smash_bar_solid_top
	8F03	LD C,A	Set iterations in C for call
	8F04	EX AF,AF'	Preserve smash_counter
	8F05	CALL draw_smash_bar_segment	Call draw_smash_bar_segment
	8F08	EX AF,AF'	Restore smash_counter
draw_smash_bar_solid_top	8F09	LD C,A	Iterations = smash_counter
	8F0A	ADD A,A	B = ~(A * 3) + 63 = amount of solid rows to draw
	8F0B	ADD A,C
	8F0C	CPL
	8F0D	ADD A,$3F
	8F0F	LD B,A
	8F10	JP draw_smash_bar_solid_bit	Call draw_smash_bar_solid_bit
draw_smash_bar_segment	8F13	LD (HL),$81	Set 8 pixels to "X......X"
	8F15	LD A,H	Save for checking in a moment
	8F16	DEC H	Move to next scanline
	8F17	AND D	Would it have rolled over into the top nibble?
	8F18	JP NZ,draw_smash_bar_segment2	No - continue
It rolled over
	8F1B	LD A,H	Put back the bit stolen by rollover
	8F1C	ADD A,E
	8F1D	LD H,A
	8F1E	LD A,L	Move to next chunk of 16 scanlines
	8F1F	SUB $20
	8F21	LD L,A
	8F22	JP NC,draw_smash_bar_segment2	Continue if it didn't roll over
	8F25	LD A,H	Otherwise move to the next chunk of 128 scanlines (would put us outside the back buffer)
	8F26	SUB E
	8F27	LD H,A
draw_smash_bar_segment2	8F28	LD (HL),$81	Set 8 pixels to "X......X"
	8F2A	LD A,H	Save for checking in a moment
	8F2B	DEC H	Move to next scanline
	8F2C	AND D	Would it have rolled over into the top nibble?
It rolled over
	8F2D	JP NZ,draw_smash_bar_segment_cont	No - continue
	8F30	LD A,H	Put back the bit stolen by rollover
	8F31	ADD A,E
	8F32	LD H,A
	8F33	LD A,L	Move to next chunk of 16 scanlines
	8F34	SUB $20
	8F36	LD L,A
	8F37	JP NC,draw_smash_bar_segment_cont	Continue if it didn't roll over
	8F3A	LD A,H	Otherwise move to the next chunk of 128 scanlines (would put us outside the back buffer)
	8F3B	SUB E
	8F3C	LD H,A
draw_smash_bar_segment_cont	8F3D	LD B,$01	1 row
	8F3F	CALL draw_smash_bar_solid_bit	Call draw_smash_bar_solid_bit
	8F42	DEC C	Loop while iterations remain
	8F43	JP NZ,draw_smash_bar_segment	Loop while iterations remain
	8F46	RET	Return
draw_smash_bar_solid_bit	8F47	LD (HL),$FF	Set 8 pixels to solid black
Move to next scanline
	8F49	LD A,H	Save for checking in a moment
	8F4A	DEC H	Move to next scanline (visually upwards)
	8F4B	AND D	Would it have rolled over into the top nibble?
	8F4C	JP NZ,draw_smash_bar_cont	No - continue
It rolled over
	8F4F	LD A,H	Put back the bit stolen by rollover
	8F50	ADD A,E
	8F51	LD H,A
	8F52	LD A,L	Move to next chunk of 16 scanlines
	8F53	SUB $20
	8F55	LD L,A
	8F56	JP NC,draw_smash_bar_cont	Continue if it didn't roll over
	8F59	LD A,H	Otherwise move to the next chunk of 128 scanlines (would put us outside the back buffer)
	8F5A	SUB E
	8F5B	LD H,A
draw_smash_bar_cont	8F5C	DJNZ draw_smash_bar_solid_bit	Loop while iterations remain
	8F5E	RET	Return