Sherlock: Routine at 50878

50878: Test The Graphics Field Of The Display Record

Used by the routine at ProcessDisplayRecord. Tests the low nibble of the record's value byte against the room graphics.
Low nibble of the record's value byte is clear?
TestLowBitsOfGraphics	50878	LD A,(IY+1)	Read the low nibble of the record's value byte and jump ahead to TestLowBitsOfGraphics_CodeFromFive when it is not zero.
	50881	AND 15
	50883	JR NZ,TestLowBitsOfGraphics_CodeFromFive
TestLowBitsOfGraphics_ReportMatch	50885	OR %00000001	Reset the zero flag.
	50887	RET	Return.
	50888	JP ParseInputNumber_ReturnZero	Return zero through ParseInputNumber_ReturnZero.
For a graphics code from 5 up to but not including 7, reads the room chosen for the graphics.
TestLowBitsOfGraphics_CodeFromFive	50891	CP 5	Jump ahead to TestLowBitsOfGraphics_CodeBelowThree if the low nibble of the value byte is below 5.
	50893	JR C,TestLowBitsOfGraphics_CodeBelowThree
	50895	CP 7	Jump ahead to TestLowBitsOfGraphics_UseGraphics if the low nibble of the value byte is at least 7.
	50897	JR NC,TestLowBitsOfGraphics_UseGraphics
	50899	LD A,(41013)	Jump to TestLowBitsOfCharacter_ClearFlag if the room graphics parameter is not 254.
	50902	CP 254
	50904	JP NZ,TestLowBitsOfCharacter_ClearFlag
	50907	LD HL,(41009)	Read the display pointer.
	50910	LD A,(IY+1)	Jump to TestLowBitsOfGraphics_TestTopBit unless the low nibble of the value byte is 5.
	50913	AND 15
	50915	CP 5
	50917	JR NZ,TestLowBitsOfGraphics_TestTopBit
	50919	BIT 7,L	Jump back to TestLowBitsOfGraphics_ReportMatch if bit 7 is clear.
	50921	JR Z,TestLowBitsOfGraphics_ReportMatch
	50923	JP TestLowBitsOfCharacter_ClearFlag	This picture does not match, so give up from TestLowBitsOfCharacter_ClearFlag.
Bit 7 of the graphics pointer selects the next picture.
TestLowBitsOfGraphics_TestTopBit	50926	BIT 7,L	Jump back to TestLowBitsOfGraphics_ReportMatch while bit 7 is present.
	50928	JR NZ,TestLowBitsOfGraphics_ReportMatch
	50930	JP TestLowBitsOfCharacter_ClearFlag	Bit 7 of the graphics pointer is clear, so give up from TestLowBitsOfCharacter_ClearFlag.
For a graphics code below 3, looks the room up and accepts it when the top flag is set.
TestLowBitsOfGraphics_CodeBelowThree	50933	CP 3	Jump ahead to TestLowBitsOfGraphics_TestMarker if the low nibble of the value byte is at least 3.
	50935	JR NC,TestLowBitsOfGraphics_TestMarker
	50937	LD A,(41013)	Read the room graphics parameter, then call FetchLocationDataPointer to look up this room.
	50940	CALL FetchLocationDataPointer
	50943	BIT 7,(IX+0)	Jump to TestLowBitsOfCharacter_ClearFlag if a marker on the record's flag byte is clear.
	50947	JP Z,TestLowBitsOfCharacter_ClearFlag
TestLowBitsOfGraphics_TestMarker	50950	BIT 0,(IY+1)	Jump to TestLowBitsOfGraphics_ReportMatch if bit 0 of the value byte is clear.
	50954	JR Z,TestLowBitsOfGraphics_ReportMatch
	50956	LD A,(41013)	Read the room graphics parameter and call FindObjectByFieldTwo to find an object by field two.
	50959	CALL FindObjectByFieldTwo
	50962	CP 255	Jump back to TestLowBitsOfCharacter_ClearFlag if the entry is the end marker.
	50964	JP Z,TestLowBitsOfCharacter_ClearFlag
	50967	JR TestLowBitsOfGraphics_ReportMatch	The entry is not the end marker, so return non-zero from TestLowBitsOfGraphics_ReportMatch.
Read the room graphics parameter and keep it for the picture.
TestLowBitsOfGraphics_UseGraphics	50969	LD A,(41013)	Read the room graphics parameter, store it in the room parameter at 52090 and keep it in C.
	50972	LD (52090),A
	50975	LD C,A
	50976	LD A,(IY+1)	Return if TestSeventhMarker returns zero.
	50979	CALL TestSeventhMarker
	50982	RET Z
	50983	BIT 4,(IY+0)	Jump to TestLowBitsOfCharacter_ReportMatch if bit 4 of the record flags is clear.
	50987	JP Z,TestLowBitsOfCharacter_ReportMatch
	50990	LD A,(IY+2)	Read record bytes 2 and 5.
	50993	LD L,(IY+5)	Read record bytes 2 and 5.
	50996	LD H,(IY+6)	Read record byte 6.
	50999	BIT 6,(IY+0)	Jump to TestLowBitsOfGraphics_TestAttribute unless bit 6 of the record flags is set.
	51003	JR Z,TestLowBitsOfGraphics_TestAttribute
	51005	LD A,(IY+4)	With a handler word present, read record bytes 4 and 7 instead.
	51008	LD L,(IY+7)
	51011	LD H,(IY+8)	Read record byte 8.
TestLowBitsOfGraphics_TestAttribute	51014	LD B,A	Use that byte as the count and call ReadObjectAttribute_LooksObjectFolds to test the object attribute.
	51015	CALL ReadObjectAttribute_LooksObjectFolds
	51018	RET NZ	Return if ReadObjectAttribute_LooksObjectFolds does not match the attribute.
	51019	JP TestLowBitsOfCharacter_MarkMatched	The attribute matched, so record it from TestLowBitsOfCharacter_MarkMatched.