Alien 8: Routine at D0B9

Used by the routine at PrintSprite.

Draws the lines of a sprite one after the other. For each line the code jumps into the unrolled code, at a place that depends on the width of the sprite, and that is set by the jump that is changed by PrintSprite. The code for a sprite that is not on a byte boundary takes a pair of bytes off the stack, which are the mask and the data, shifts them across the two bytes of the buffer that they fall into with the table of shifted bytes in H, and keeps what is left of the second byte to go with the next pair. A sprite on a byte boundary jumps into DrawAlignedColumns instead.

Used by the routine at PrintSprite. Draws the lines of a sprite one after the other. For each line the code jumps into the unrolled code, at a place that depends on the width of the sprite, and that is set by the jump that is changed by PrintSprite. The code for a sprite that is not on a byte boundary takes a pair of bytes off the stack, which are the mask and the data, shifts them across the two bytes of the buffer that they fall into with the table of shifted bytes in H, and keeps what is left of the second byte to go with the next pair. A sprite on a byte boundary jumps into DrawAlignedColumns instead.
Jump into the unrolled columns.
DrawLines	D0B9	EX AF,AF'	Copy A to A'.
	D0BA	LD A,(BC)	Fetch the first byte of the buffer.
DrawLines_Jump	D0BB	JR DrawLines_Jump	Jump into the unrolled columns.
The patched jump at DrawLines_Jump lands here when the sprite is five columns wide.
DrawLines_FirstPair	D0BD	POP DE	Draw the first pair of a sprite that has five.
	D0BE	LD L,E
	D0BF	AND (HL)
	D0C0	LD L,D
	D0C1	XOR (HL)
	D0C2	CPL
	D0C3	LD (BC),A
	D0C4	INC BC
	D0C5	INC H
	D0C6	LD L,E
	D0C7	LD A,(BC)
	D0C8	AND (HL)
	D0C9	LD L,D
	D0CA	XOR (HL)
	D0CB	CPL
	D0CC	DEC H
	D0CD	POP DE	Draw the second pair of a sprite that has four or five.
	D0CE	LD L,E
	D0CF	AND (HL)
	D0D0	LD L,D
	D0D1	XOR (HL)
	D0D2	CPL
	D0D3	LD (BC),A
	D0D4	INC BC
	D0D5	INC H
	D0D6	LD L,E
	D0D7	LD A,(BC)
	D0D8	AND (HL)
	D0D9	LD L,D
	D0DA	XOR (HL)
	D0DB	CPL
	D0DC	DEC H
	D0DD	POP DE	Draw the third pair of a sprite that has three or more.
	D0DE	LD L,E
	D0DF	AND (HL)
	D0E0	LD L,D
	D0E1	XOR (HL)
	D0E2	CPL
	D0E3	LD (BC),A
	D0E4	INC BC
	D0E5	INC H
	D0E6	LD L,E
	D0E7	LD A,(BC)
	D0E8	AND (HL)
	D0E9	LD L,D
	D0EA	XOR (HL)
	D0EB	CPL
	D0EC	DEC H
	D0ED	POP DE	Draw the fourth pair of a sprite that has two or more.
	D0EE	LD L,E
	D0EF	AND (HL)
	D0F0	LD L,D
	D0F1	XOR (HL)
	D0F2	CPL
	D0F3	LD (BC),A
	D0F4	INC BC
	D0F5	INC H
	D0F6	LD L,E
	D0F7	LD A,(BC)
	D0F8	AND (HL)
	D0F9	LD L,D
	D0FA	XOR (HL)
	D0FB	CPL
	D0FC	DEC H
	D0FD	POP DE	Draw the last pair.
	D0FE	LD L,E
	D0FF	AND (HL)
	D100	LD L,D
	D101	XOR (HL)
	D102	CPL
	D103	LD (BC),A
	D104	INC BC
	D105	INC H
	D106	LD L,E
	D107	LD A,(BC)
	D108	AND (HL)
	D109	LD L,D
	D10A	XOR (HL)
	D10B	CPL
	D10C	DEC H
	D10D	LD (BC),A	Write the last byte of the line.
This entry point is used by the routine at DrawAlignedColumns. Step on to the next line. The aligned columns jump here after their last column.
DrawLines_Next	D10E	LD A,C	Fetch C.
DrawLines_Step	D10F	ADD A,$00	Add the step, which is changed for the width of the sprite.
	D111	LD C,A	Copy it to C.
	D112	LD A,B	Fetch B.
	D113	ADC A,$00	Add 00 with carry.
	D115	LD B,A	Copy it to B.
	D116	EX AF,AF'	Fetch A'.
	D117	DEC A	Decrement A.
	D118	JP NZ,DrawLines	Jump to DrawLines if it is not zero.
	D11B	LD SP,($5B09)	Fetch SavedStackPointer and return.
	D11F	RET	Fetch SavedStackPointer and return.
View the equivalent code in; Knight Lore Pentagram