8-Bit Software

The BBC and Master Computer Public Domain Library

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9384 RENUMBER

Submitted by Steve Fewell

Description:

Call routine &934D to read the Starting Line Number and Line increment parameters (if any were specified) as follows:: * Set the IWA to 10 (the default program starting Line Number); * Call routine &9B1E to detokenise and extract the line number at BASIC text pointer A location and store it; in the IWA. If no line number was found at BASIC text pointer A then the IWA will retain; the default value of 10.; * Push the IWA value (the starting line number) to the BASIC stack; * Set the IWA to 10 (the default line number increment); * If the next non-space character is not comma ',', then no line increment parameter has been specified, so call &9BB0; to check that the statement is terminated correctly (with a ':', '<cr>' or 'ELSE-token'; terminator character), [if not then a 'Syntax error' will be issued] and exit routine &934D.; * Otherwise, call routine &9B1E to detokenise and extract the Line number value from the BASIC Text pointer A; location and store it in the IWA. The IWA now contains the specified Line increment value.; * If byte &2B of the IWA contains a non-zero value, then the increment value is more than 255, so issue error; 'Silly', as the line increment cannot be more than 255.; * If byte &2A (the LSB) of the IWA contains a zero value, then the increment value is zero, so issue error; 'Silly', as the line increment cannot be zero.; * Call &9BA6 to skip any space characters and check that the statement is terminated correctly (with a ':',; '<cr>' or 'ELSE-token' terminator character), [if not then a 'Syntax error' will be; issued] and exit routine &934D.

On return from routine &934D, the Integer on the BASIC stack is the Start Line Number and the IWA contains the step
size.

Retrieve the Start Line number from the BASIC stack and store it in locations &39-&3A (bytes &3B-&3C are
unused as the Integer should only be 2-bytes wide). This is the renumbered line number counter.
Call routine &BDE5 to check that the program can be read correctly ('Bad program' message is displayed if the program
cannot be correctly read).

Call routine &9373 to set locations &3B-&3C to point to TOP (the end of the program) and to set &37-&38 to
point to PAGE+1 (the start of the program ignoring the first '<cr>' character) and to set Y to 1.

Renumber - Phase 1: Store all current line numbers in the program in the free storage space after TOP
Use the free space after TOP (pointed to by &3B-&3C) to store a copy of all of of the Line numbers present in the
program (and to issue an error if there is not enough space to store this required informaton) as follows.
[&9392] Read the next character (offset 0) from the &37-&38 pointer.
If the character is negative (end of program reached) then jump to &93C4 (all line numbers are stored, so continue to
the main RENUMBER routine).

Store the character (the first byte of the Line Number) at the location pointed to by the &3B-&3C pointer, i.e. the
free space after the TOP of the program. Read the next character (offset 1) from the &37-&38 pointer and store this
character in the next free space pointed to by &3B-&3C (offset 1). This value is the second byte of the Line Number
value.
Add 2 to the &3B-&3C pointer (to point to the next free location after the program end).
Compare the &3B-&3C pointer address with HIMEM (stored in locations &06-&07). If &3B-&3C exceeds
(or is equal to) HIMEM then issue 'RENUMBER space' error (and terminate the RENUMBER operation).
Otherwise, call routine &947A to update &37-&38 to point to the start of the next program line.
Jump back to &9392 to copy the next program line number.

Renumber - Phase 2: Replace all line numbers in the program with the renumbered line numbers
[&93C4] Call routine &937B to set &37-&38 to point to PAGE + 1 and to set Y to 1.
[&93C7] Load the first character of the Line's Line number. If the character is negative (end of program reached) then
jump to &93E7 to start the next phase of the renumbering.
Replace the Line number on the current line with the next renumbered Line Number (from locations &39-&3A (storing
&3A first)).

Add the Step Size (&2A) to the renumbered Line Number counter (&39-&3A (&3A is the MSB)).
Correct the &39-&3A Line Number if it has exceeded 32767 (&7FFF) by resetting bit 7 to 0 (removing the &8000
value from the value). So &39-&3A now contains the next renumbered Line Number.
Call routine &947A to update &37-&38 to point to the start of the next program line.
Jump back to &93C7 to replace the next program line number.

Renumber - Phase 3: Replace all line number references in the program with the correct renumbered version
[&93E7] Set BASIC Text pointer A (&0B-&0C) to PAGE (&18, the start of the program code).
[&93ED] Load the first character (the Line Number) of the program line pointed to by &0B-&0C.
If the character is negative then we have reached the end of the program, so jump to &8F83 to initialise the BASIC
variable space (as we have just destroyed any previously defined variables by placing the old line number values after TOP)
and prompt for the user's next command line input - as the RENUMBER operation is complete.

Set Y (the line offset value) to 4 (so that the Line Number and line length byte values are ignored).
Zero location &2C (the quote toggle flag).

[&93F7] Read the next byte of the program line pointed to by the address in locations &0B-&0C (offset Y).

If &2C is zero (then we are not inside a quote) so:: * If the character is '#&8D' (Line number token) then jump to &941B to renumber the line number (this routine; is described below). This token usually follows a GOSUB, GOTO, THEN or ELSE keyword and is; followed by the literal line number; * If the character is '#&F4' [REM-token] then jump to &9412 to skip the rest of the current program line

[&9405] Increment Y (to point to the next character on the line)
If the current character (that was read by &93F7) is a quote (") then EOR the character with &2C (to
toggle the flag value).
If the character is not '<cr>' (carriage return) then jump back to &93F7 to check the next character of the
program line.
[&9412] Otherwise, skip the line end and move on to the next line by Adding the value at offset 3 of the current line
(which is the line length value) to the &0B-&0C pointer [and set the &0A offset to 1] and jump back to &93ED
to check the next program line for line numbers to renumber.

Renumber the Line Number specified after the line number token ('#&8D')
[&941B] Now a line number token has been encountered within a program line. This routine will now renumber the line
number so that it addresses the correct renumbered line.

Call &9B2A to set the IWA to the Line Number (after the Line number token value -'&8D').
Call routine &9373 to set &3B-&3C to TOP and &37-&38 to PAGE+1.
[&9421] Load the character at the &37-&38 location.

If the character is negative then the end of the program has been reached without finding a matching program Line, so jump to &945C to:: * Print the text "Failed at "; * Store A in &2B (the Line number MSB); * Store the character pointed to by &0B-&0C (the line number LSB) to location &2A; * Call routine &A081 to display the line number (in the IWA) on the screen - this outputs the line number that; contained the failed reference; * Call routine &BA92 to output a new line; * Jump to &9446 to Set Y to &0A (the current position of the program line in the phase 3 search) and jump to; &93F7 to continue checking the next character of the program line (for further line number; references.

Compare the IWA line number with the next Line Number at the &3B-&3C pointed (i.e. the next line number that was
stored after the end of the program).

If the line numbers are not equal then the matching renumbered line has not yet been found so:: * [&944A] Clear the carry flag (so that we don't add an extra 1 to the &37-&38 pointer); * Call routine &947A to update the &37-&38 pointer to point to the next program line (by adding the line; length byte (offset 3 from the current &37-&38 start of line pointer) to the &37-&38; pointer and reset Y to 1.; * Add 2 to the &3B-&3C pointer (so that the pointer points to the next unrenumbered line number stored after; the end of the program.; * Jump back to &9421 to check the next line of the program for a match

Otherwise (we have found a match), so store the new renumbered line number (from the &37-&38 pointer location) in the current program position - to replace the reference with the renumbered reference - as follows:: * Store the Line number MSB ((&37,&38)+1) in location &3D; * Store the Line Number LSB (pointed to by (&37, &38)) in X register; * Set Y = the BASIC Text Pointer A offset - 1; * Set &39-&3A to the current &0B-&0C pointer location (i.e. the line containing the reference); * Call routine &8D62 to tokenise the Program Line Number (in X and &3D) and store it at the ((&39-&3A)+1); location; * Set Y to the BASIC Text pointer A offset (&0A); * Jump to &93F7 to continue with the next character of the program line (pointed to by &0B-&0C)

Disassembly for the RENUMBER routine

934D		169 010	A9 0A	LDA#&0A
934F		032 024 174	20 18 AE	JSR &AE18 Set IWA to the 8-bit value in A
9352		032 030 155	20 1E 9B	JSR &9B1E Detokenise the Line Number at PTR A & Set IWA to the Line Number value
9355	&	032 038 188	20 26 BC	JSR &BC26 Push IWA value to the BASIC Stack [pushi]
9358		169 010	A9 0A	LDA#&0A
935A		032 024 174	20 18 AE	JSR &AE18 Set IWA to the 8-bit value in A
935D		032 229 140	20 E5 8C	JSR &8CE5 Compare next non-space [PTR A] character with ','
9360		208 014	D0 0E	BNE 14 --> &9370
9362		032 030 155	20 1E 9B	JSR &9B1E Detokenise the Line Number at PTR A & Set IWA to the Line Number value
9365	+	165 043	A5 2B	LDA &2B
9367	S	208 083	D0 53	BNE 83 --> &93BC 'Silly' error
9369	*	165 042	A5 2A	LDA &2A
936B	O	240 079	F0 4F	BEQ 79 --> &93BC 'Silly' error
936D	L	076 166 155	4C A6 9B	JMP &9BA6 Skip spaces and check end of Statement
9370	L	076 176 155	4C B0 9B	JMP &9BB0 Check for end of Statement
9373		165 018	A5 12	LDA &12
9375	;	133 059	85 3B	STA &3B
9377		165 019	A5 13	LDA &13
9379	<	133 060	85 3C	STA &3C
937B		165 024	A5 18	LDA &18
937D	8	133 056	85 38	STA &38
937F		160 001	A0 01	LDY#&01
9381	7	132 055	84 37	STY &37
9383	`	096	60	RTS
9384	M	032 077 147	20 4D 93	JSR &934D Read Start line and line increment parameters
9387	9	162 057	A2 39	LDX#&39
9389		032 008 189	20 08 BD	JSR &BD08 Pop Integer from Stack to Zero page address
938C		032 229 189	20 E5 BD	JSR &BDE5 Check program can be read correctly ('Bad program' message if not)
938F	s	032 115 147	20 73 93	JSR &9373 Set &3B-&3C to TOP and &37-&38 to PAGE+1
9392	7	178 055	B2 37	LDA (&37)
9394	0.	048 046	30 2E	BMI 46 --> &93C4
9396	;	146 059	92 3B	STA (&3B)
9398	7	177 055	B1 37	LDA (&37),Y
939A	;	145 059	91 3B	STA (&3B),Y
939C	8	056	38	SEC
939D		152	98	TYA
939E	e;	101 059	65 3B	ADC &3B
93A0	;	133 059	85 3B	STA &3B
93A2		144 002	90 02	BCC 2 --> &93A6
93A4	<	230 060	E6 3C	INC &3C
93A6		197 006	C5 06	CMP &06
93A8	<	165 060	A5 3C	LDA &3C
93AA		229 007	E5 07	SBC &07
93AC		176 005	B0 05	BCS 5 --> &93B3 'RENUMBER space' error
93AE	z	032 122 148	20 7A 94	JSR &947A Advance &37-&38 to point to the next Program Line
93B1		128 223	80 DF	BRA -33 --> &9392
93B3				... 'Silly' error...
93BC				... 'RENUMBER space' error...
93C4	{	032 123 147	20 7B 93	JSR &937B Set &37-&38 to PAGE+1
93C7	7	178 055	B2 37	LDA (&37)
93C9	0	048 028	30 1C	BMI 28 --> &93E7
93CB	:	165 058	A5 3A	LDA &3A
93CD	7	146 055	92 37	STA (&37)
93CF	9	165 057	A5 39	LDA &39
93D1	7	145 055	91 37	STA (&37),Y
93D3		024	18	CLC
93D4	9	165 057	A5 39	LDA &39
93D6	e*	101 042	65 2A	ADC &2A
93D8	9	133 057	85 39	STA &39
93DA		169 000	A9 00	LDA#&00
93DC	e:	101 058	65 3A	ADC &3A
93DE	)	041 127	29 7F	AND#&7F
93E0	:	133 058	85 3A	STA &3A
93E2	z	032 122 148	20 7A 94	JSR &947A Advance &37-&38 to point to the next Program Line
93E5		128 224	80 E0	BRA -32 --> &93C7
93E7		165 024	A5 18	LDA &18
93E9		133 012	85 0C	STA &0C
93EB	d	100 011	64 0B	STZ &0B
93ED		160 001	A0 01	LDY#&01
93EF		177 011	B1 0B	LDA (&0B),Y
93F1	0g	048 103	30 67	BMI 103 --> &945A
93F3		160 004	A0 04	LDY#&04
93F5	d,	100 044	64 2C	STZ &2C
93F7		177 011	B1 0B	LDA (&0B),Y
93F9	,	166 044	A6 2C	LDX &2C
93FB		208 008	D0 08	BNE 8 --> &9405
93FD		201 141	C9 8D	CMP#&8D
93FF		240 026	F0 1A	BEQ 26 --> &941B
9401		201 244	C9 F4	CMP#&F4
9403		240 013	F0 0D	BEQ 13 --> &9412
9405		200	C8	INY
9406	"	201 034	C9 22	CMP#&22
9408		208 004	D0 04	BNE 4 --> &940E
940A	E,	069 044	45 2C	EOR &2C
940C	,	133 044	85 2C	STA &2C
940E		201 013	C9 0D	CMP#&0D
9410		208 229	D0 E5	BNE -27 --> &93F7
9412		160 003	A0 03	LDY#&03
9414		177 011	B1 0B	LDA (&0B),Y
9416		032 244 155	20 F4 9B	JSR &9BF4 Add A to PTR A pointer (&0B,&0C) & set PTR A (&0A) offset to 1
9419		128 210	80 D2	BRA -46 --> &93ED
941B	*	032 042 155	20 2A 9B	JSR &9B2A Detokenise Line Number at PTR A (without skip spaces or skip #&8D char) & Set IWA to the Line Number value
941E	s	032 115 147	20 73 93	JSR &9373 Set &3B-&3C to TOP and &37-&38 to PAGE+1
9421	7	178 055	B2 37	LDA (&37)
9423	07	048 055	30 37	BMI 55 --> &945C
9425	;	178 059	B2 3B	LDA (&3B)
9427	+	197 043	C5 2B	CMP &2B
9429		208 031	D0 1F	BNE 31 --> &944A
942B	;	177 059	B1 3B	LDA (&3B),Y
942D	*	197 042	C5 2A	CMP &2A
942F		208 025	D0 19	BNE 25 --> &944A
9431	7	177 055	B1 37	LDA (&37),Y
9433	=	133 061	85 3D	STA &3D
9435	7	178 055	B2 37	LDA (&37)
9437		170	AA	TAX
9438		164 010	A4 0A	LDY &0A
943A		136	88	DEY
943B		165 011	A5 0B	LDA &0B
943D	9	133 057	85 39	STA &39
943F		165 012	A5 0C	LDA &0C
9441	:	133 058	85 3A	STA &3A
9443	b	032 098 141	20 62 8D	JSR &8D62 Tokenise program line & store at location specified by &39-&3A (which is &0B-&0C)
9446		164 010	A4 0A	LDY &0A
9448		128 173	80 AD	BRA -83 --> &93F7
944A		024	18	CLC
944B	z	032 122 148	20 7A 94	JSR &947A Advance &37-&38 to point to the next Program Line
944E	;	165 059	A5 3B	LDA &3B
9450	i	105 002	69 02	ADC#&02
9452	;	133 059	85 3B	STA &3B
9454		144 203	90 CB	BCC -53 --> &9421
9456	<	230 060	E6 3C	INC &3C
9458		128 199	80 C7	BRA -57 --> &9421
945A	Z	128 090	80 5A	BRA 90 --> &94B6 [JMP &8F83 Initialise & prompt for next command line]
945C		032 207 190	20 CF BE	JSR &BECF Print following text as a warning message & jump to address specified
945F	Failed at	070 097 105 108 101 100 032 097 116 032	46 61 69 6C 65 64 20 61 74 20	EQUS "Failed at "
9469		177	B1	EQUB &B1
946A		011	0B	EQUB &0B
946B	+	133 043	85 2B	STA &2B
946D		200	C8	INY
946E		177 011	B1 0B	LDA (&0B),Y
9470	*	133 042	85 2A	STA &2A
9472		032 129 160	20 81 A0	JSR &A081 Print Line Number on screen (width 0)
9475		032 146 186	20 92 BA	JSR &BA92 Start new output line
9478		128 204	80 CC	BRA -52 --> &9446
947A		200	C8	INY
947B	7	177 055	B1 37	LDA (&37),Y
947D		160 001	A0 01	LDY#&01
947F	e7	101 055	65 37	ADC &37
9481	7	133 055	85 37	STA &37
9483		144 003	90 03	BCC 3 --> &9488
9485	8	230 056	E6 38	INC &38
9487		024	18	CLC
9488	`	096	60	RTS