Atic Atac: Routine at 9A0A

The handler of DrawGraphic for a graphic that is turned a quarter turn anti-clockwise. Each row of the screen is made from a column of the graphic, from the right-hand side to the left-hand side. The bits for each byte come from eight rows of the graphic, which are gathered up in H' using the mask in L'.

The handler of DrawGraphic for a graphic that is turned a quarter turn anti-clockwise. Each row of the screen is made from a column of the graphic, from the right-hand side to the left-hand side. The bits for each byte come from eight rows of the graphic, which are gathered up in H' using the mask in L'.
DrawGraphic_RotatedLeft	9A0A	POP BC	Restore the attribute and graphic ID from the stack.
	9A0B	CALL GetBlendInstruction	Call GetBlendInstruction to get the instruction to mix the graphic with the screen.
	9A0E	LD ($9A36),A	Write it over the instruction at 9A36.
	9A11	CALL GetGraphicDetails	Call GetGraphicDetails to get the details of the graphic.
	9A14	LD A,B	Fetch the width.
	9A15	EXX	Switch to the shadow registers.
	9A16	LD L,$01	L'=01 (the mask for the first column).
	9A18	LD B,A	Keep the number of columns in B'.
	9A19	EXX	Switch back to the main registers.
	9A1A	CALL AddWidthToAddress	Call AddWidthToAddress to move DE on to the second row.
	9A1D	DEC DE	Move DE back to the last byte of the first row.
DrawGraphic_RotatedLeft_Row	9A1E	PUSH BC	Stash the width and height on the stack.
	9A1F	PUSH DE	Stash the position in the graphic on the stack.
	9A20	PUSH HL	Stash the screen address on the stack.
DrawGraphic_RotatedLeft_Bit	9A21	LD A,(DE)	Fetch the byte of the graphic.
	9A22	EXX	Switch to the shadow registers.
	9A23	AND L	Mask the column.
	9A24	JR Z,DrawGraphic_RotatedLeft_Shift	Jump to DrawGraphic_RotatedLeft_Shift if the bit is not set.
	9A26	SCF	Set the carry flag.
DrawGraphic_RotatedLeft_Shift	9A27	RL H	Shift the bit into H'.
	9A29	EXX	Switch back to the main registers.
	9A2A	CALL AddWidthToAddress	Call AddWidthToAddress to move down to the next row of the graphic.
	9A2D	DEC C	Decrease the height by one.
	9A2E	LD A,C	Fetch the number of rows left.
	9A2F	AND %00000111	Keep only bits 0-2.
	9A31	JR NZ,DrawGraphic_RotatedLeft_Bit	Jump to DrawGraphic_RotatedLeft_Bit until eight bits have been gathered.
	9A33	EXX	Switch to the shadow registers.
	9A34	LD A,H	Fetch the byte that was built from the column.
	9A35	EXX	Switch back to the main registers.
	9A36	NOP	This is replaced by an instruction that mixes A with the screen.
	9A37	LD (HL),A	Write A to the screen.
	9A38	INC L	Move HL on to the next byte.
	9A39	LD A,C	Fetch the number of rows left.
	9A3A	AND A	Jump to DrawGraphic_RotatedLeft_Bit if there are more bytes in this row of the screen.
	9A3B	JR NZ,DrawGraphic_RotatedLeft_Bit
	9A3D	POP HL	Restore the screen address from the stack.
	9A3E	CALL ScreenPosition1PixelAbove	Call ScreenPosition1PixelAbove to move up a line.
	9A41	POP DE	Restore the position in the graphic from the stack.
	9A42	POP BC	Restore the width and height from the stack.
	9A43	EXX	Switch to the shadow registers.
	9A44	RLC L	Move the mask on to the next column.
	9A46	EXX	Switch back to the main registers.
	9A47	JR NC,DrawGraphic_RotatedLeft_Row	Jump to DrawGraphic_RotatedLeft_Row if there are more columns in this byte.
	9A49	EXX	Switch to the shadow registers.
	9A4A	DEC B	Decrease the number of columns by one.
	9A4B	EXX	Switch back to the main registers.
	9A4C	RET Z	Return if all of the columns have been drawn.
	9A4D	DEC DE	Move DE back to the previous byte.
	9A4E	JR DrawGraphic_RotatedLeft_Row	Jump back to DrawGraphic_RotatedLeft_Row to draw the next row of the graphic.