Krakout: Render the tile map to the screen

990B: Render the tile map to the screen

Renders every tile-map cell into the back buffer, then copies the back buffer to the display file.
render_tilemap	990B	LD HL,tilemap	Start at the tile map.
	990E	LD BC,TILEMAP_SIZE	Process every cell.
render_tilemap_0	9911	PUSH BC	Each cell: hold the counter and the map pointer across the glyph copy.
	9912	PUSH HL
	9913	LD A,(HL)	Read the tile value.
	9914	LD L,A	Read the tile value.
	9915	LD H,$00	Point DE at the tile's bitmap in the tile set, 8 bytes per tile.
	9917	ADD HL,HL
	9918	ADD HL,HL
	9919	ADD HL,HL
	991A	LD DE,TILEGFX_BASE
	991D	ADD HL,DE
	991E	EX DE,HL
	991F	POP HL
	9920	PUSH HL
	9921	LD A,H	Build the back-buffer destination from the cell's screen-third (high bits).
	9922	AND $03
	9924	RLCA
	9925	RLCA
	9926	RLCA
	9927	ADD A,BACKBUF_BASE/$100
	9929	LD H,A
	992A	LD A,(DE)	Copy the 8 glyph rows into the back buffer (INC H steps down pixel rows).
	992B	LD (HL),A
	992C	INC H
	992D	INC DE
	992E	LD A,(DE)
	992F	LD (HL),A
	9930	INC H
	9931	INC DE
	9932	LD A,(DE)
	9933	LD (HL),A
	9934	INC H
	9935	INC DE
	9936	LD A,(DE)
	9937	LD (HL),A
	9938	INC H
	9939	INC DE
	993A	LD A,(DE)
	993B	LD (HL),A
	993C	INC H
	993D	INC DE
	993E	LD A,(DE)
	993F	LD (HL),A
	9940	INC H
	9941	INC DE
	9942	LD A,(DE)
	9943	LD (HL),A
	9944	INC H
	9945	INC DE
	9946	LD A,(DE)
	9947	LD (HL),A
	9948	POP HL
	9949	INC HL
	994A	POP BC
	994B	DEC BC
	994C	LD A,B
	994D	OR C
	994E	JR NZ,render_tilemap_0
	9950	LD HL,BACKBUF_BASE	Finally copy the whole back buffer to the display file.
	9953	LD DE,SCREEN_BASE
	9956	LD BC,SCREEN_SIZE
	9959	LDIR
	995B	RET

Routines