Atic Atac: Routine at 39434

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	39434	POP BC	Restore the attribute and graphic ID from the stack.
	39435	CALL GetBlendInstruction	Call GetBlendInstruction to get the instruction to mix the graphic with the screen.
	39438	LD (39478),A	Write it over the instruction at 39478.
	39441	CALL GetGraphicDetails	Call GetGraphicDetails to get the details of the graphic.
	39444	LD A,B	Fetch the width.
	39445	EXX	Switch to the shadow registers.
	39446	LD L,1	L'=1 (the mask for the first column).
	39448	LD B,A	Keep the number of columns in B'.
	39449	EXX	Switch back to the main registers.
	39450	CALL AddWidthToAddress	Call AddWidthToAddress to move DE on to the second row.
	39453	DEC DE	Move DE back to the last byte of the first row.
DrawGraphic_RotatedLeft_Row	39454	PUSH BC	Stash the width and height on the stack.
	39455	PUSH DE	Stash the position in the graphic on the stack.
	39456	PUSH HL	Stash the screen address on the stack.
DrawGraphic_RotatedLeft_Bit	39457	LD A,(DE)	Fetch the byte of the graphic.
	39458	EXX	Switch to the shadow registers.
	39459	AND L	Mask the column.
	39460	JR Z,DrawGraphic_RotatedLeft_Shift	Jump to DrawGraphic_RotatedLeft_Shift if the bit is not set.
	39462	SCF	Set the carry flag.
DrawGraphic_RotatedLeft_Shift	39463	RL H	Shift the bit into H'.
	39465	EXX	Switch back to the main registers.
	39466	CALL AddWidthToAddress	Call AddWidthToAddress to move down to the next row of the graphic.
	39469	DEC C	Decrease the height by one.
	39470	LD A,C	Fetch the number of rows left.
	39471	AND %00000111	Keep only bits 0-2.
	39473	JR NZ,DrawGraphic_RotatedLeft_Bit	Jump to DrawGraphic_RotatedLeft_Bit until eight bits have been gathered.
	39475	EXX	Switch to the shadow registers.
	39476	LD A,H	Fetch the byte that was built from the column.
	39477	EXX	Switch back to the main registers.
	39478	NOP	This is replaced by an instruction that mixes A with the screen.
	39479	LD (HL),A	Write A to the screen.
	39480	INC L	Move HL on to the next byte.
	39481	LD A,C	Fetch the number of rows left.
	39482	AND A	Jump to DrawGraphic_RotatedLeft_Bit if there are more bytes in this row of the screen.
	39483	JR NZ,DrawGraphic_RotatedLeft_Bit
	39485	POP HL	Restore the screen address from the stack.
	39486	CALL ScreenPosition1PixelAbove	Call ScreenPosition1PixelAbove to move up a line.
	39489	POP DE	Restore the position in the graphic from the stack.
	39490	POP BC	Restore the width and height from the stack.
	39491	EXX	Switch to the shadow registers.
	39492	RLC L	Move the mask on to the next column.
	39494	EXX	Switch back to the main registers.
	39495	JR NC,DrawGraphic_RotatedLeft_Row	Jump to DrawGraphic_RotatedLeft_Row if there are more columns in this byte.
	39497	EXX	Switch to the shadow registers.
	39498	DEC B	Decrease the number of columns by one.
	39499	EXX	Switch back to the main registers.
	39500	RET Z	Return if all of the columns have been drawn.
	39501	DEC DE	Move DE back to the previous byte.
	39502	JR DrawGraphic_RotatedLeft_Row	Jump back to DrawGraphic_RotatedLeft_Row to draw the next row of the graphic.