Sherlock: Routine at 50728

50728: Test The Character Field Of The Display Record

Used by the routine at ProcessDisplayRecord. Tests the low nibble of the record flags against the room and the object.
Low nibble of the record flags is clear?
TestLowBitsOfCharacter	50728	LD A,(IY+0)	Read the low nibble of the record flags and jump ahead to TestLowBitsOfCharacter_CodeFromFive when it is not zero.
	50731	AND 15
	50733	JR NZ,TestLowBitsOfCharacter_CodeFromFive
This entry point is used by the routines at TestLowBitsOfGraphics, ReadHighByteSource and TestSeventhMarker.
TestLowBitsOfCharacter_ReportMatch	50735	OR %00000001	Reset the zero flag.
	50737	RET	Return.
This entry point is used by the routine at TestSeventhMarker. The character field did not match.
TestLowBitsOfCharacter_GiveUp	50738	JP ParseInputNumber_ReturnZero	Return zero through ParseInputNumber_ReturnZero.
For a picture code from 5 up to but not including 7, reads the room chosen for the picture.
TestLowBitsOfCharacter_CodeFromFive	50741	CP 5	Jump ahead to TestLowBitsOfCharacter_CodeBelowThree if the low nibble of the record flags is below 5.
	50743	JR C,TestLowBitsOfCharacter_CodeBelowThree
	50745	CP 7	Jump ahead to TestLowBitsOfCharacter_UseRoom if the low nibble of the record flags is at least 7.
	50747	JR NC,TestLowBitsOfCharacter_UseRoom
	50749	LD A,(41012)	Jump to TestLowBitsOfCharacter_ClearFlag if the room display parameter is not 254.
	50752	CP 254
	50754	JR NZ,TestLowBitsOfCharacter_ClearFlag
	50756	LD HL,(41007)	Read the display pointer.
	50759	LD A,(IY+0)	Jump to TestLowBitsOfCharacter_TestTopBit unless the low nibble of the record flags is 5.
	50762	AND 15
	50764	CP 5
	50766	JR NZ,TestLowBitsOfCharacter_TestTopBit
	50768	BIT 7,L	Jump back to TestLowBitsOfCharacter_ReportMatch if bit 7 is clear.
	50770	JR Z,TestLowBitsOfCharacter_ReportMatch
This entry point is used by the routine at TestLowBitsOfGraphics.
TestLowBitsOfCharacter_ClearFlag	50772	XOR A	Clear the byte at 40993 and return zero through TestLowBitsOfCharacter_GiveUp.
	50773	LD (40993),A
	50776	JR TestLowBitsOfCharacter_GiveUp
Bit 7 of the room pointer selects the next picture.
TestLowBitsOfCharacter_TestTopBit	50778	BIT 7,L	Jump back to TestLowBitsOfCharacter_ReportMatch while bit 7 is present.
	50780	JR NZ,TestLowBitsOfCharacter_ReportMatch
	50782	JR TestLowBitsOfCharacter_ClearFlag	Bit 7 of the room pointer is clear, so give up from TestLowBitsOfCharacter_ClearFlag.
For a code below 3, looks the room up and accepts it when the top flag is set.
TestLowBitsOfCharacter_CodeBelowThree	50784	CP 3	Jump ahead to TestLowBitsOfCharacter_TestMarker if the low nibble of the record flags is at least 3.
	50786	JR NC,TestLowBitsOfCharacter_TestMarker
	50788	LD A,(41012)	Read the room display parameter, then call FetchLocationDataPointer to look up this room.
	50791	CALL FetchLocationDataPointer
	50794	BIT 7,(IX+0)	Jump to TestLowBitsOfCharacter_ClearFlag if a marker on the record's flag byte is clear.
	50798	JR Z,TestLowBitsOfCharacter_ClearFlag
TestLowBitsOfCharacter_TestMarker	50800	BIT 0,(IY+0)	Jump to TestLowBitsOfCharacter_ReportMatch if bit 0 of the record flags is clear.
	50804	JR Z,TestLowBitsOfCharacter_ReportMatch
	50806	LD A,(41012)	Read the room display parameter and call FindObjectByFieldTwo to find an object by field two.
	50809	CALL FindObjectByFieldTwo
	50812	CP 255	Jump back to TestLowBitsOfCharacter_ClearFlag if the entry is the end marker.
	50814	JR Z,TestLowBitsOfCharacter_ClearFlag
	50816	JR TestLowBitsOfCharacter_ReportMatch	The entry is not the end marker, so return non-zero from TestLowBitsOfCharacter_ReportMatch.
Read the room display parameter, record it in the room parameter at 52090 and keep it in C.
TestLowBitsOfCharacter_UseRoom	50818	LD A,(41012)	Read the room display parameter, store it in the room parameter at 52090 and keep it in C.
	50821	LD (52090),A
	50824	LD C,A
	50825	LD A,(IY+0)	Test the record flags through TestSeventhMarker and go to TestLowBitsOfCharacter_ClearFlag if it returns zero.
	50828	CALL TestSeventhMarker
	50831	JR Z,TestLowBitsOfCharacter_ClearFlag
	50833	BIT 4,(IY+0)	Jump to TestLowBitsOfCharacter_ReportMatch if bit 4 of the record flags is clear.
	50837	JR Z,TestLowBitsOfCharacter_ReportMatch
	50839	LD A,(IY+2)	Read record bytes 2 and 3.
	50842	LD L,(IY+3)	Read record bytes 2 and 3.
	50845	LD H,(IY+4)	Read record byte 4 as the high byte.
	50848	BIT 6,(IY+0)	Jump to TestLowBitsOfCharacter_ShiftNibble unless bit 6 of the record flags is set.
	50852	JR Z,TestLowBitsOfCharacter_ShiftNibble
	50854	LD A,(IY+4)	With a handler word present, read record bytes 4-6 instead.
	50857	LD L,(IY+5)	With a handler word present, read record bytes 4-6 instead.
	50860	LD H,(IY+6)	Read record byte 6 as the high byte.
TestLowBitsOfCharacter_ShiftNibble	50863	RRCA	Shift the parameter down by four bits and call ReadObjectAttribute_LooksObjectFolds to test the object attribute.
	50864	RRCA
	50865	RRCA
	50866	RRCA
	50867	LD B,A
	50868	CALL ReadObjectAttribute_LooksObjectFolds
	50871	RET NZ	Return if ReadObjectAttribute_LooksObjectFolds does not match the attribute.
This entry point is used by the routine at TestLowBitsOfGraphics.
TestLowBitsOfCharacter_MarkMatched	50872	LD A,1	Write 1 to the byte at 40993.
	50874	LD (40993),A	Write 1 to the byte at 40993.
	50877	RET	Return.