Spectrum ROM: Routine at 06137

06137: THE 'LIST' ENTRY POINT

The address of this routine is found in the parameter table. The 'main screen' channel will need to be opened.
LIST	06137	LD A,2	Use stream 2.
This entry point is used by the routine at LLIST.
LIST_1	06139	LD (IY+2),0	Signal 'an ordinary listing in the main part of the screen' (reset bit 4 of TV-FLAG and all other bits).
	06143	CALL SYNTAX_Z	Open the channel unless checking syntax.
	06146	CALL NZ,CHAN_OPEN	Open the channel unless checking syntax.
	06149	RST 24	With the present character in the A register see if the stream is to be changed.
	06150	CALL STR_ALTER
	06153	JR C,LIST_4	Jump forward if unchanged.
	06155	RST 24	Is the present character a ';'?
	06156	CP ";"	Is the present character a ';'?
	06158	JR Z,LIST_2	Jump if it is.
	06160	CP ","	Is it a ','?
	06162	JR NZ,LIST_3	Jump if it is not.
LIST_2	06164	RST 32	A numeric expression must follow, e.g. LIST #5,20.
	06165	CALL CLASS_06	A numeric expression must follow, e.g. LIST #5,20.
	06168	JR LIST_5	Jump forward with it.
LIST_3	06170	CALL USE_ZERO	Otherwise use zero and also jump forward.
	06173	JR LIST_5	Otherwise use zero and also jump forward.
Come here if the stream was unaltered.
LIST_4	06175	CALL FETCH_NUM	Fetch any line or use zero if none supplied.
LIST_5	06178	CALL CHECK_END	If checking the syntax of the edit-line move on to the next statement.
	06181	CALL FIND_INT2	Line number to BC.
	06184	LD A,B	High byte to A.
	06185	AND 63	Limit the high byte to the correct range and pass the whole line number to HL.
	06187	LD H,A
	06188	LD L,C
	06189	LD (23625),HL	Set E-PPC and find the address of the start of this line or the first line after it if the actual line does not exist.
	06192	CALL LINE_ADDR
This entry point is used by the routine at AUTO_LIST.
LIST_ALL	06195	LD E,1	Flag 'before the current line'.
Now the controlling loop for printing a series of lines is entered.
LIST_ALL_1	06197	CALL OUT_LINE	Print the whole of a BASIC line.
	06200	RST 16	This will be a 'carriage return'.
	06201	BIT 4,(IY+2)	Jump back unless dealing with an automatic listing (bit 4 of TV-FLAG set).
	06205	JR Z,LIST_ALL_1
	06207	LD A,(23659)	Also jump back if there is still part of the main screen that can be used (DF-SZ <> S-POSN-hi).
	06210	SUB (IY+79)
	06213	JR NZ,LIST_ALL_1
	06215	XOR E	A return can be made at this point if the screen is full and the current line has been printed (E=0).
	06216	RET Z
	06217	PUSH HL	However if the current line is missing from the listing then S-TOP has to be updated and a further line printed (using scrolling).
	06218	PUSH DE
	06219	LD HL,23660
	06222	CALL LN_FETCH
	06225	POP DE
	06226	POP HL
	06227	JR LIST_ALL_1