CPU-Z80-Disassembler
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t/data/zx48.asm view on Meta::CPAN
CALL L15D4 ; routine WAIT-KEY - input address is KEY-NEXT
; but is reset to KEY-INPUT
LD E,A ; save first in E
;; ED-CONTR
L0F6C: CALL L15D4 ; routine WAIT-KEY for control.
; input address will be key-next.
PUSH DE ; saved code/parameters
LD HL,($5C5B) ; fetch address of keyboard cursor from K_CUR
RES 0,(IY+$07) ; set MODE to 'L'
CALL L1655 ; routine MAKE-ROOM makes 2/3 spaces at cursor
POP BC ; restore code/parameters
INC HL ; address first location
LD (HL),B ; place code (ink etc.)
INC HL ; address next
LD (HL),C ; place possible parameter. If only one
; then DE points to this location also.
JR L0F8B ; forward to ADD-CH-1
; ------------------------
; Add code to current line
; ------------------------
; this is the branch used to add normal non-control characters
; with ED-LOOP as the stacked return address.
; it is also the OUTPUT service routine for system channel 'R'.
;; ADD-CHAR
L0F81: RES 0,(IY+$07) ; set MODE to 'L'
X0F85: LD HL,($5C5B) ; fetch address of keyboard cursor from K_CUR
CALL L1652 ; routine ONE-SPACE creates one space.
; either a continuation of above or from ED-CONTR with ED-LOOP on stack.
;; ADD-CH-1
L0F8B: LD (DE),A ; load current character to last new location.
INC DE ; address next
LD ($5C5B),DE ; and update K_CUR system variable.
RET ; return - either a simple return
t/data/zx48.asm view on Meta::CPAN
; using a look-up table.
;; ED-KEYS
L0F92: LD E,A ; character to E.
LD D,$00 ; prepare to add.
LD HL,L0FA0 - 7 ; base address of editing keys table. $0F99
ADD HL,DE ; add E
LD E,(HL) ; fetch offset to E
ADD HL,DE ; add offset for address of handling routine.
PUSH HL ; push the address on machine stack.
LD HL,($5C5B) ; load address of cursor from K_CUR.
RET ; Make an indirect jump forward to routine.
; ------------------
; Editing keys table
; ------------------
; For each code in the range $07 to $0F this table contains a
; single offset byte to the routine that services that code.
; Note. for what was intended there should also have been an
; entry for chr$ 6 with offset to ed-symbol.
t/data/zx48.asm view on Meta::CPAN
CALL L196E ; routine LINE-ADDR to find address of line
; or following line if it doesn't exist.
CALL L1695 ; routine LINE-NO will get line number from
; address or previous line if at end-marker.
LD A,D ; if there is no program then DE will
OR E ; contain zero so test for this.
JP Z,L1097 ; jump to CLEAR-SP if so.
; Note. at this point we have a validated line number, not just an
; approximation and it would be best to update E_PPC with the true
; cursor line value which would enable the line cursor to be suppressed
; in all situations - see shortly.
PUSH HL ; save address of line.
INC HL ; address low byte of length.
LD C,(HL) ; transfer to C
INC HL ; next to high byte
LD B,(HL) ; transfer to B.
LD HL,$000A ; an overhead of ten bytes
ADD HL,BC ; is added to length.
LD B,H ; transfer adjusted value
t/data/zx48.asm view on Meta::CPAN
CALL L1097 ; routine CLEAR-SP clears editing area.
LD HL,($5C51) ; address CURCHL
EX (SP),HL ; swap with line address on stack
PUSH HL ; save line address underneath
LD A,$FF ; select system channel 'R'
CALL L1601 ; routine CHAN-OPEN opens it
POP HL ; drop line address
DEC HL ; make it point to first byte of line num.
DEC (IY+$0F) ; decrease E_PPC_lo to suppress line cursor.
; Note. ineffective when E_PPC is one
; greater than last line of program perhaps
; as a result of a delete.
; credit. Paul Harrison 1982.
CALL L1855 ; routine OUT-LINE outputs the BASIC line
; to the editing area.
INC (IY+$0F) ; restore E_PPC_lo to the previous value.
LD HL,($5C59) ; address E_LINE in editing area.
INC HL ; advance
t/data/zx48.asm view on Meta::CPAN
LD ($5C5B),HL ; update K_CUR to address start of BASIC.
POP HL ; restore the address of CURCHL.
CALL L1615 ; routine CHAN-FLAG sets flags for it.
RET ; RETURN to ED-LOOP.
; -------------------
; Cursor down editing
; -------------------
; The BASIC lines are displayed at the top of the screen and the user
; wishes to move the cursor down one line in edit mode.
; With INPUT LINE, this key must be used instead of entering STOP.
;; ED-DOWN
L0FF3: BIT 5,(IY+$37) ; test FLAGX - Input Mode ?
JR NZ,L1001 ; skip to ED-STOP if so
LD HL,$5C49 ; address E_PPC - 'current line'
CALL L190F ; routine LN-FETCH fetches number of next
; line or same if at end of program.
JR L106E ; forward to ED-LIST to produce an
t/data/zx48.asm view on Meta::CPAN
; ---
;; ED-STOP
L1001: LD (IY+$00),$10 ; set ERR_NR to 'STOP in INPUT' code
JR L1024 ; forward to ED-ENTER to produce error.
; -------------------
; Cursor left editing
; -------------------
; This acts on the cursor in the lower section of the screen in both
; editing and input mode.
;; ED-LEFT
L1007: CALL L1031 ; routine ED-EDGE moves left if possible
JR L1011 ; forward to ED-CUR to update K-CUR
; and return to ED-LOOP.
; --------------------
; Cursor right editing
; --------------------
; This acts on the cursor in the lower screen in both editing and input
; mode and moves it to the right.
;; ED-RIGHT
L100C: LD A,(HL) ; fetch addressed character.
CP $0D ; is it carriage return ?
RET Z ; return if so to ED-LOOP
INC HL ; address next character
;; ED-CUR
L1011: LD ($5C5B),HL ; update K_CUR system variable
RET ; return to ED-LOOP
; --------------
; DELETE editing
; --------------
; This acts on the lower screen and deletes the character to left of
; cursor. If control characters are present these are deleted first
; leaving the naked parameter (0-7) which appears as a '?' except in the
; case of chr$ 6 which is the comma control character. It is not mandatory
; to delete these second characters.
;; ED-DELETE
L1015: CALL L1031 ; routine ED-EDGE moves cursor to left.
LD BC,$0001 ; of character to be deleted.
JP L19E8 ; to RECLAIM-2 reclaim the character.
; ------------------------------------------
; Ignore next 2 codes from key-input routine
; ------------------------------------------
; Since AT and TAB cannot be entered this point is never reached
; from the keyboard. If inputting from a tape device or network then
; the control and two following characters are ignored and processing
; continues as if a carriage return had been received.
t/data/zx48.asm view on Meta::CPAN
;; ED-END
L1026: POP HL ; the previous value of ERR_SP
LD ($5C3D),HL ; is restored to ERR_SP system variable
BIT 7,(IY+$00) ; is ERR_NR $FF (= 'OK') ?
RET NZ ; return if so
LD SP,HL ; else put error routine on stack
RET ; and make an indirect jump to it.
; -----------------------------
; Move cursor left when editing
; -----------------------------
; This routine moves the cursor left. The complication is that it must
; not position the cursor between control codes and their parameters.
; It is further complicated in that it deals with TAB and AT characters
; which are never present from the keyboard.
; The method is to advance from the beginning of the line each time,
; jumping one, two, or three characters as necessary saving the original
; position at each jump in DE. Once it arrives at the cursor then the next
; legitimate leftmost position is in DE.
;; ED-EDGE
L1031: SCF ; carry flag must be set to call the nested
CALL L1195 ; subroutine SET-DE.
; if input then DE=WORKSP
; if editing then DE=E_LINE
SBC HL,DE ; subtract address from start of line
ADD HL,DE ; and add back.
INC HL ; adjust for carry.
POP BC ; drop return address
RET C ; return to ED-LOOP if already at left
; of line.
PUSH BC ; resave return address - ED-LOOP.
LD B,H ; transfer HL - cursor address
LD C,L ; to BC register pair.
; at this point DE addresses start of line.
;; ED-EDGE-1
L103E: LD H,D ; transfer DE - leftmost pointer
LD L,E ; to HL
INC HL ; address next leftmost character to
; advance position each time.
LD A,(DE) ; pick up previous in A
AND $F0 ; lose the low bits
t/data/zx48.asm view on Meta::CPAN
LD A,(DE) ; reload leftmost character
SUB $17 ; decimal 23 ('tab')
ADC A,$00 ; will be 0 for 'tab' and 'at'.
JR NZ,L1051 ; forward to ED-EDGE-2 if not
; HL has been incremented twice
INC HL ; increment a third time for 'at'/'tab'
;; ED-EDGE-2
L1051: AND A ; prepare for true subtraction
SBC HL,BC ; subtract cursor address from pointer
ADD HL,BC ; and add back
; Note when HL matches the cursor position BC,
; there is no carry and the previous
; position is in DE.
EX DE,HL ; transfer result to DE if looping again.
; transfer DE to HL to be used as K-CUR
; if exiting loop.
JR C,L103E ; back to ED-EDGE-1 if cursor not matched.
RET ; return.
; -----------------
; Cursor up editing
; -----------------
; The main screen displays part of the BASIC program and the user wishes
; to move up one line scrolling if necessary.
; This has no alternative use in input mode.
t/data/zx48.asm view on Meta::CPAN
;; KEY-DONE2
L111B: SCF ; set carry flag to show a key has been found
RET ; and return.
; --------------------
; Lower screen copying
; --------------------
; This subroutine is called whenever the line in the editing area or
; input workspace is required to be printed to the lower screen.
; It is by calling this routine after any change that the cursor, for
; instance, appears to move to the left.
; Remember the edit line will contain characters and tokens
; e.g. "1000 LET a=1" is 8 characters.
;; ED-COPY
L111D: CALL L0D4D ; routine TEMPS sets temporary attributes.
RES 3,(IY+$02) ; update TV_FLAG - signal no change in mode
RES 5,(IY+$02) ; update TV_FLAG - signal don't clear lower
; screen.
LD HL,($5C8A) ; fetch SPOSNL
t/data/zx48.asm view on Meta::CPAN
CALL L1195 ; call routine SET-DE
; if in input DE = WORKSP
; if in edit DE = E_LINE
EX DE,HL ; start address to HL
CALL L187D ; routine OUT-LINE2 outputs entire line up to
; carriage return including initial
; characterized line number when present.
EX DE,HL ; transfer new address to DE
CALL L18E1 ; routine OUT-CURS considers a
; terminating cursor.
LD HL,($5C8A) ; fetch updated SPOSNL
EX (SP),HL ; exchange with ECHO_E on stack
EX DE,HL ; transfer ECHO_E to DE
CALL L0D4D ; routine TEMPS to re-set attributes
; if altered.
; the lower screen was not cleared, at the outset, so if deleting then old
; text from a previous print may follow this line and requires blanking.
t/data/zx48.asm view on Meta::CPAN
; This routine uses HL only and returns with that register holding
; WORKSP/STKBOT/STKEND though no use is made of this. The routines also
; reset MEM to its usual place in the systems variable area should it
; have been relocated to a FOR-NEXT variable. The main entry point
; SET-MIN is called at the start of the MAIN-EXEC loop and prior to
; displaying an error.
;; SET-MIN
L16B0: LD HL,($5C59) ; fetch E_LINE
LD (HL),$0D ; insert carriage return
LD ($5C5B),HL ; make K_CUR keyboard cursor point there.
INC HL ; next location
LD (HL),$80 ; holds end-marker $80
INC HL ; next location becomes
LD ($5C61),HL ; start of WORKSP
; This entry point is used prior to input and prior to the execution,
; or parsing, of each statement.
;; SET-WORK
L16BF: LD HL,($5C61) ; fetch WORKSP value
t/data/zx48.asm view on Meta::CPAN
; Print a whole BASIC line
; ------------------------
; This routine prints a whole BASIC line and it is called
; from LIST-ALL to output the line to current channel
; and from ED-EDIT to 'sprint' the line to the edit buffer.
;; OUT-LINE
L1855: LD BC,($5C49) ; fetch E_PPC the current line which may be
; unchecked and not exist.
CALL L1980 ; routine CP-LINES finds match or line after.
LD D,$3E ; prepare cursor '>' in D.
JR Z,L1865 ; to OUT-LINE1 if matched or line after.
LD DE,$0000 ; put zero in D, to suppress line cursor.
RL E ; pick up carry in E if line before current
; leave E zero if same or after.
;; OUT-LINE1
L1865: LD (IY+$2D),E ; save flag in BREG which is spare.
LD A,(HL) ; get high byte of line number.
CP $40 ; is it too high ($2F is maximum possible) ?
POP BC ; drop the return address and
RET NC ; make an early return if so >>>
PUSH BC ; save return address
CALL L1A28 ; routine OUT-NUM-2 to print addressed number
; with leading space.
INC HL ; skip low number byte.
INC HL ; and the two
INC HL ; length bytes.
RES 0,(IY+$01) ; update FLAGS - signal leading space required.
LD A,D ; fetch the cursor.
AND A ; test for zero.
JR Z,L1881 ; to OUT-LINE3 if zero.
RST 10H ; PRINT-A prints '>' the current line cursor.
; this entry point is called from ED-COPY
;; OUT-LINE2
L187D: SET 0,(IY+$01) ; update FLAGS - suppress leading space.
;; OUT-LINE3
L1881: PUSH DE ; save flag E for a return value.
EX DE,HL ; save HL address in DE.
RES 2,(IY+$30) ; update FLAGS2 - signal NOT in QUOTES.
t/data/zx48.asm view on Meta::CPAN
L1894: LD HL,($5C5F) ; fetch X_PTR - possibly the error pointer
; address.
AND A ; clear the carry flag.
SBC HL,DE ; test if an error address has been reached.
JR NZ,L18A1 ; forward to OUT-LINE5 if not.
LD A,$3F ; load A with '?' the error marker.
CALL L18C1 ; routine OUT-FLASH to print flashing marker.
;; OUT-LINE5
L18A1: CALL L18E1 ; routine OUT-CURS will print the cursor if
; this is the right position.
EX DE,HL ; restore address pointer to HL.
LD A,(HL) ; fetch the addressed character.
CALL L18B6 ; routine NUMBER skips a hidden floating
; point number if present.
INC HL ; now increment the pointer.
CP $0D ; is character end-of-line ?
JR Z,L18B4 ; to OUT-LINE6, if so, as line is finished.
EX DE,HL ; save the pointer in DE.
t/data/zx48.asm view on Meta::CPAN
INC HL ;
INC HL ;
INC HL ;
LD A,(HL) ; fetch the following character
RET ; for return value.
; --------------------------
; Print a flashing character
; --------------------------
; This subroutine is called from OUT-LINE to print a flashing error
; marker '?' or from the next routine to print a flashing cursor e.g. 'L'.
; However, this only gets called from OUT-LINE when printing the edit line
; or the input buffer to the lower screen so a direct call to $09F4 can
; be used, even though out-line outputs to other streams.
; In fact the alternate set is used for the whole routine.
;; OUT-FLASH
L18C1: EXX ; switch in alternate set
LD HL,($5C8F) ; fetch L = ATTR_T, H = MASK-T
PUSH HL ; save masks.
t/data/zx48.asm view on Meta::CPAN
POP HL ; pop P_FLAG to H.
LD (IY+$57),H ; and restore system variable P_FLAG.
POP HL ; restore temporary masks
LD ($5C8F),HL ; and restore system variables ATTR_T/MASK_T
EXX ; switch back to main set
RET ; return
; ----------------
; Print the cursor
; ----------------
; This routine is called before any character is output while outputting
; a BASIC line or the input buffer. This includes listing to a printer
; or screen, copying a BASIC line to the edit buffer and printing the
; input buffer or edit buffer to the lower screen. It is only in the
; latter two cases that it has any relevance and in the last case it
; performs another very important function also.
;; OUT-CURS
L18E1: LD HL,($5C5B) ; fetch K_CUR the current cursor address
AND A ; prepare for true subtraction.
SBC HL,DE ; test against pointer address in DE and
RET NZ ; return if not at exact position.
; the value of MODE, maintained by KEY-INPUT, is tested and if non-zero
; then this value 'E' or 'G' will take precedence.
LD A,($5C41) ; fetch MODE 0='KLC', 1='E', 2='G'.
RLC A ; double the value and set flags.
JR Z,L18F3 ; to OUT-C-1 if still zero ('KLC').
ADD A,$43 ; add 'C' - will become 'E' if originally 1
; or 'G' if originally 2.
JR L1909 ; forward to OUT-C-2 to print.
; ---
; If mode was zero then, while printing a BASIC line, bit 2 of flags has been
; set if 'THEN' or ':' was encountered as a main character and reset otherwise.
; This is now used to determine if the 'K' cursor is to be printed but this
; transient state is also now transferred permanently to bit 3 of FLAGS
; to let the interrupt routine know how to decode the next key.
;; OUT-C-1
L18F3: LD HL,$5C3B ; Address FLAGS
RES 3,(HL) ; signal 'K' mode initially.
LD A,$4B ; prepare letter 'K'.
BIT 2,(HL) ; test FLAGS - was the
; previous main character ':' or 'THEN' ?
JR Z,L1909 ; forward to OUT-C-2 if so to print.
t/data/zx48.asm view on Meta::CPAN
L195A: CP $22 ; is it quote character '"' ?
JR NZ,L1968 ; to OUT-CH-2 with others to set 'L' mode.
PUSH AF ; save character.
LD A,($5C6A) ; fetch FLAGS2.
XOR $04 ; toggle the quotes flag.
LD ($5C6A),A ; update FLAGS2
POP AF ; and restore character.
;; OUT-CH-2
L1968: SET 2,(IY+$01) ; update FLAGS - signal L mode if the cursor
; is next.
;; OUT-CH-3
L196C: RST 10H ; PRINT-A vectors the character to
; channel 'S', 'K', 'R' or 'P'.
RET ; return.
; -------------------------------------------
; Get starting address of line, or line after
; -------------------------------------------
t/data/zx48.asm view on Meta::CPAN
RRCA ; lose bit 0.
RRCA ; test if quotes required.
JR NC,L2129 ; forward to IN-PR-3 if not.
LD A,$22 ; load the '"' character
LD (DE),A ; place quote in first new location at DE.
DEC HL ; decrease HL - from carriage return.
LD (HL),A ; and place a quote in second location.
;; IN-PR-3
L2129: LD ($5C5B),HL ; set keyboard cursor K_CUR to HL
BIT 7,(IY+$37) ; test FLAGX - is this INPUT LINE ??
JR NZ,L215E ; forward to IN-VAR-3 if so as input will
; be accepted without checking its syntax.
LD HL,($5C5D) ; fetch CH_ADD
PUSH HL ; and save on stack.
LD HL,($5C3D) ; fetch ERR_SP
PUSH HL ; and save on stack
;; IN-VAR-1
t/data/zx48.asm view on Meta::CPAN
; the jump was to here when using INPUT LINE.
;; IN-VAR-3
L215E: CALL L0F2C ; routine EDITOR is called for input
; when ENTER received rejoin other route but with no syntax check.
; INPUT and INPUT LINE converge here.
;; IN-VAR-4
L2161: LD (IY+$22),$00 ; set K_CUR_hi to a low value so that the cursor
; no longer appears in the input line.
CALL L21D6 ; routine IN-CHAN-K tests if the keyboard
; is being used for input.
JR NZ,L2174 ; forward to IN-VAR-5 if using another input
; channel.
; continue here if using the keyboard.
CALL L111D ; routine ED-COPY overprints the edit line
; to the lower screen. The only visible
; affect is that the cursor disappears.
; if you're inputting more than one item in
; a statement then that becomes apparent.
LD BC,($5C82) ; fetch line and column from ECHO_E
CALL L0DD9 ; routine CL-SET sets S-POSNL to those
; values.
; if using another input channel rejoin here.
;; IN-VAR-5
t/data/zx48_base.asm view on Meta::CPAN
call WAIT_KEY ; routine WAIT-KEY - input address is KEY-NEXT
; but is reset to KEY-INPUT
ld e,a ; save first in E
;; ED-CONTR
ED_CONTR:
call WAIT_KEY ; routine WAIT-KEY for control.
; input address will be key-next.
push de ; saved code/parameters
ld hl,(0x5C5B) ; fetch address of keyboard cursor from K_CUR
res 0,(iy+0x07) ; set MODE to 'L'
call MAKE_ROOM ; routine MAKE-ROOM makes 2/3 spaces at cursor
pop bc ; restore code/parameters
inc hl ; address first location
ld (hl),b ; place code (ink etc.)
inc hl ; address next
ld (hl),c ; place possible parameter. If only one
; then DE points to this location also.
jr ADD_CH_1 ; forward to ADD-CH-1
; ------------------------
t/data/zx48_base.asm view on Meta::CPAN
; ------------------------
; this is the branch used to add normal non-control characters
; with ED-LOOP as the stacked return address.
; it is also the OUTPUT service routine for system channel 'R'.
;; ADD-CHAR
ADD_CHAR:
res 0,(iy+0x07) ; set MODE to 'L'
X0F85:
ld hl,(0x5C5B) ; fetch address of keyboard cursor from K_CUR
call ONE_SPACE ; routine ONE-SPACE creates one space.
; either a continuation of above or from ED-CONTR with ED-LOOP on stack.
;; ADD-CH-1
ADD_CH_1:
ld (de),a ; load current character to last new location.
inc de ; address next
ld (0x5C5B),de ; and update K_CUR system variable.
t/data/zx48_base.asm view on Meta::CPAN
;; ED-KEYS
ED_KEYS:
ld e,a ; character to E.
ld d,0x00 ; prepare to add.
ld hl,ed_keys_t - 7 ; base address of editing keys table. $0F99
add hl,de ; add E
ld e,(hl) ; fetch offset to E
add hl,de ; add offset for address of handling routine.
push hl ; push the address on machine stack.
ld hl,(0x5C5B) ; load address of cursor from K_CUR.
ret ; Make an indirect jump forward to routine.
; ------------------
; Editing keys table
; ------------------
; For each code in the range $07 to $0F this table contains a
; single offset byte to the routine that services that code.
; Note. for what was intended there should also have been an
; entry for chr$ 6 with offset to ed-symbol.
t/data/zx48_base.asm view on Meta::CPAN
call LINE_ADDR ; routine LINE-ADDR to find address of line
; or following line if it doesn't exist.
call LINE_NO ; routine LINE-NO will get line number from
; address or previous line if at end-marker.
ld a,d ; if there is no program then DE will
or e ; contain zero so test for this.
jp z,CLEAR_SP ; jump to CLEAR-SP if so.
; Note. at this point we have a validated line number, not just an
; approximation and it would be best to update E_PPC with the true
; cursor line value which would enable the line cursor to be suppressed
; in all situations - see shortly.
push hl ; save address of line.
inc hl ; address low byte of length.
ld c,(hl) ; transfer to C
inc hl ; next to high byte
ld b,(hl) ; transfer to B.
ld hl,0x000A ; an overhead of ten bytes
add hl,bc ; is added to length.
ld b,h ; transfer adjusted value
t/data/zx48_base.asm view on Meta::CPAN
call CLEAR_SP ; routine CLEAR-SP clears editing area.
ld hl,(0x5C51) ; address CURCHL
ex (sp),hl ; swap with line address on stack
push hl ; save line address underneath
ld a,0xFF ; select system channel 'R'
call CHAN_OPEN ; routine CHAN-OPEN opens it
pop hl ; drop line address
dec hl ; make it point to first byte of line num.
dec (iy+0x0F) ; decrease E_PPC_lo to suppress line cursor.
; Note. ineffective when E_PPC is one
; greater than last line of program perhaps
; as a result of a delete.
; credit. Paul Harrison 1982.
call OUT_LINE ; routine OUT-LINE outputs the BASIC line
; to the editing area.
inc (iy+0x0F) ; restore E_PPC_lo to the previous value.
ld hl,(0x5C59) ; address E_LINE in editing area.
inc hl ; advance
t/data/zx48_base.asm view on Meta::CPAN
ld (0x5C5B),hl ; update K_CUR to address start of BASIC.
pop hl ; restore the address of CURCHL.
call CHAN_FLAG ; routine CHAN-FLAG sets flags for it.
ret ; RETURN to ED-LOOP.
; -------------------
; Cursor down editing
; -------------------
; The BASIC lines are displayed at the top of the screen and the user
; wishes to move the cursor down one line in edit mode.
; With INPUT LINE, this key must be used instead of entering STOP.
;; ED-DOWN
ED_DOWN:
bit 5,(iy+0x37) ; test FLAGX - Input Mode ?
jr nz,ED_STOP ; skip to ED-STOP if so
ld hl,0x5C49 ; address E_PPC - 'current line'
call LN_FETCH ; routine LN-FETCH fetches number of next
; line or same if at end of program.
t/data/zx48_base.asm view on Meta::CPAN
; ---
;; ED-STOP
ED_STOP:
ld (iy+0x00),0x10 ; set ERR_NR to 'STOP in INPUT' code
jr ED_ENTER ; forward to ED-ENTER to produce error.
; -------------------
; Cursor left editing
; -------------------
; This acts on the cursor in the lower section of the screen in both
; editing and input mode.
;; ED-LEFT
ED_LEFT:
call ED_EDGE ; routine ED-EDGE moves left if possible
jr ED_CUR ; forward to ED-CUR to update K-CUR
; and return to ED-LOOP.
; --------------------
; Cursor right editing
; --------------------
; This acts on the cursor in the lower screen in both editing and input
; mode and moves it to the right.
;; ED-RIGHT
ED_RIGHT:
ld a,(hl) ; fetch addressed character.
cp 0x0D ; is it carriage return ?
ret z ; return if so to ED-LOOP
inc hl ; address next character
;; ED-CUR
ED_CUR:
ld (0x5C5B),hl ; update K_CUR system variable
ret ; return to ED-LOOP
; --------------
; DELETE editing
; --------------
; This acts on the lower screen and deletes the character to left of
; cursor. If control characters are present these are deleted first
; leaving the naked parameter (0-7) which appears as a '?' except in the
; case of chr$ 6 which is the comma control character. It is not mandatory
; to delete these second characters.
;; ED-DELETE
ED_DELETE:
call ED_EDGE ; routine ED-EDGE moves cursor to left.
ld bc,0x0001 ; of character to be deleted.
jp RECLAIM_2 ; to RECLAIM-2 reclaim the character.
; ------------------------------------------
; Ignore next 2 codes from key-input routine
; ------------------------------------------
; Since AT and TAB cannot be entered this point is never reached
; from the keyboard. If inputting from a tape device or network then
; the control and two following characters are ignored and processing
; continues as if a carriage return had been received.
t/data/zx48_base.asm view on Meta::CPAN
ED_END:
pop hl ; the previous value of ERR_SP
ld (0x5C3D),hl ; is restored to ERR_SP system variable
bit 7,(iy+0x00) ; is ERR_NR $FF (= 'OK') ?
ret nz ; return if so
ld sp,hl ; else put error routine on stack
ret ; and make an indirect jump to it.
; -----------------------------
; Move cursor left when editing
; -----------------------------
; This routine moves the cursor left. The complication is that it must
; not position the cursor between control codes and their parameters.
; It is further complicated in that it deals with TAB and AT characters
; which are never present from the keyboard.
; The method is to advance from the beginning of the line each time,
; jumping one, two, or three characters as necessary saving the original
; position at each jump in DE. Once it arrives at the cursor then the next
; legitimate leftmost position is in DE.
;; ED-EDGE
ED_EDGE:
scf ; carry flag must be set to call the nested
call SET_DE ; subroutine SET-DE.
; if input then DE=WORKSP
; if editing then DE=E_LINE
sbc hl,de ; subtract address from start of line
add hl,de ; and add back.
inc hl ; adjust for carry.
pop bc ; drop return address
ret c ; return to ED-LOOP if already at left
; of line.
push bc ; resave return address - ED-LOOP.
ld b,h ; transfer HL - cursor address
ld c,l ; to BC register pair.
; at this point DE addresses start of line.
;; ED-EDGE-1
ED_EDGE_1:
ld h,d ; transfer DE - leftmost pointer
ld l,e ; to HL
inc hl ; address next leftmost character to
; advance position each time.
ld a,(de) ; pick up previous in A
t/data/zx48_base.asm view on Meta::CPAN
sub 0x17 ; decimal 23 ('tab')
adc a,0x00 ; will be 0 for 'tab' and 'at'.
jr nz,ED_EDGE_2 ; forward to ED-EDGE-2 if not
; HL has been incremented twice
inc hl ; increment a third time for 'at'/'tab'
;; ED-EDGE-2
ED_EDGE_2:
and a ; prepare for true subtraction
sbc hl,bc ; subtract cursor address from pointer
add hl,bc ; and add back
; Note when HL matches the cursor position BC,
; there is no carry and the previous
; position is in DE.
ex de,hl ; transfer result to DE if looping again.
; transfer DE to HL to be used as K-CUR
; if exiting loop.
jr c,ED_EDGE_1 ; back to ED-EDGE-1 if cursor not matched.
ret ; return.
; -----------------
; Cursor up editing
; -----------------
; The main screen displays part of the BASIC program and the user wishes
; to move up one line scrolling if necessary.
; This has no alternative use in input mode.
t/data/zx48_base.asm view on Meta::CPAN
;; KEY-DONE2
KEY_DONE2:
scf ; set carry flag to show a key has been found
ret ; and return.
; --------------------
; Lower screen copying
; --------------------
; This subroutine is called whenever the line in the editing area or
; input workspace is required to be printed to the lower screen.
; It is by calling this routine after any change that the cursor, for
; instance, appears to move to the left.
; Remember the edit line will contain characters and tokens
; e.g. "1000 LET a=1" is 8 characters.
;; ED-COPY
ED_COPY:
call TEMPS ; routine TEMPS sets temporary attributes.
res 3,(iy+0x02) ; update TV_FLAG - signal no change in mode
res 5,(iy+0x02) ; update TV_FLAG - signal don't clear lower
; screen.
t/data/zx48_base.asm view on Meta::CPAN
call SET_DE ; call routine SET-DE
; if in input DE = WORKSP
; if in edit DE = E_LINE
ex de,hl ; start address to HL
call OUT_LINE2 ; routine OUT-LINE2 outputs entire line up to
; carriage return including initial
; characterized line number when present.
ex de,hl ; transfer new address to DE
call OUT_CURS ; routine OUT-CURS considers a
; terminating cursor.
ld hl,(0x5C8A) ; fetch updated SPOSNL
ex (sp),hl ; exchange with ECHO_E on stack
ex de,hl ; transfer ECHO_E to DE
call TEMPS ; routine TEMPS to re-set attributes
; if altered.
; the lower screen was not cleared, at the outset, so if deleting then old
; text from a previous print may follow this line and requires blanking.
t/data/zx48_base.asm view on Meta::CPAN
; WORKSP/STKBOT/STKEND though no use is made of this. The routines also
; reset MEM to its usual place in the systems variable area should it
; have been relocated to a FOR-NEXT variable. The main entry point
; SET-MIN is called at the start of the MAIN-EXEC loop and prior to
; displaying an error.
;; SET-MIN
SET_MIN:
ld hl,(0x5C59) ; fetch E_LINE
ld (hl),0x0D ; insert carriage return
ld (0x5C5B),hl ; make K_CUR keyboard cursor point there.
inc hl ; next location
ld (hl),0x80 ; holds end-marker $80
inc hl ; next location becomes
ld (0x5C61),hl ; start of WORKSP
; This entry point is used prior to input and prior to the execution,
; or parsing, of each statement.
;; SET-WORK
SET_WORK:
t/data/zx48_base.asm view on Meta::CPAN
; ------------------------
; This routine prints a whole BASIC line and it is called
; from LIST-ALL to output the line to current channel
; and from ED-EDIT to 'sprint' the line to the edit buffer.
;; OUT-LINE
OUT_LINE:
ld bc,(0x5C49) ; fetch E_PPC the current line which may be
; unchecked and not exist.
call CP_LINES ; routine CP-LINES finds match or line after.
ld d,0x3E ; prepare cursor '>' in D.
jr z,OUT_LINE1 ; to OUT-LINE1 if matched or line after.
ld de,0x0000 ; put zero in D, to suppress line cursor.
rl e ; pick up carry in E if line before current
; leave E zero if same or after.
;; OUT-LINE1
OUT_LINE1:
ld (iy+0x2D),e ; save flag in BREG which is spare.
ld a,(hl) ; get high byte of line number.
cp 0x40 ; is it too high ($2F is maximum possible) ?
pop bc ; drop the return address and
ret nc ; make an early return if so >>>
push bc ; save return address
call OUT_NUM_2 ; routine OUT-NUM-2 to print addressed number
; with leading space.
inc hl ; skip low number byte.
inc hl ; and the two
inc hl ; length bytes.
res 0,(iy+0x01) ; update FLAGS - signal leading space required.
ld a,d ; fetch the cursor.
and a ; test for zero.
jr z,OUT_LINE3 ; to OUT-LINE3 if zero.
rst 0x10 ; PRINT-A prints '>' the current line cursor.
; this entry point is called from ED-COPY
;; OUT-LINE2
OUT_LINE2:
set 0,(iy+0x01) ; update FLAGS - suppress leading space.
;; OUT-LINE3
OUT_LINE3:
push de ; save flag E for a return value.
t/data/zx48_base.asm view on Meta::CPAN
; address.
and a ; clear the carry flag.
sbc hl,de ; test if an error address has been reached.
jr nz,OUT_LINE5 ; forward to OUT-LINE5 if not.
ld a,0x3F ; load A with '?' the error marker.
call OUT_FLASH ; routine OUT-FLASH to print flashing marker.
;; OUT-LINE5
OUT_LINE5:
call OUT_CURS ; routine OUT-CURS will print the cursor if
; this is the right position.
ex de,hl ; restore address pointer to HL.
ld a,(hl) ; fetch the addressed character.
call NUMBER ; routine NUMBER skips a hidden floating
; point number if present.
inc hl ; now increment the pointer.
cp 0x0D ; is character end-of-line ?
jr z,OUT_LINE6 ; to OUT-LINE6, if so, as line is finished.
ex de,hl ; save the pointer in DE.
t/data/zx48_base.asm view on Meta::CPAN
inc hl
inc hl
inc hl
ld a,(hl) ; fetch the following character
ret ; for return value.
; --------------------------
; Print a flashing character
; --------------------------
; This subroutine is called from OUT-LINE to print a flashing error
; marker '?' or from the next routine to print a flashing cursor e.g. 'L'.
; However, this only gets called from OUT-LINE when printing the edit line
; or the input buffer to the lower screen so a direct call to $09F4 can
; be used, even though out-line outputs to other streams.
; In fact the alternate set is used for the whole routine.
;; OUT-FLASH
OUT_FLASH:
exx ; switch in alternate set
ld hl,(0x5C8F) ; fetch L = ATTR_T, H = MASK-T
t/data/zx48_base.asm view on Meta::CPAN
pop hl ; pop P_FLAG to H.
ld (iy+0x57),h ; and restore system variable P_FLAG.
pop hl ; restore temporary masks
ld (0x5C8F),hl ; and restore system variables ATTR_T/MASK_T
exx ; switch back to main set
ret ; return
; ----------------
; Print the cursor
; ----------------
; This routine is called before any character is output while outputting
; a BASIC line or the input buffer. This includes listing to a printer
; or screen, copying a BASIC line to the edit buffer and printing the
; input buffer or edit buffer to the lower screen. It is only in the
; latter two cases that it has any relevance and in the last case it
; performs another very important function also.
;; OUT-CURS
OUT_CURS:
ld hl,(0x5C5B) ; fetch K_CUR the current cursor address
and a ; prepare for true subtraction.
sbc hl,de ; test against pointer address in DE and
ret nz ; return if not at exact position.
; the value of MODE, maintained by KEY-INPUT, is tested and if non-zero
; then this value 'E' or 'G' will take precedence.
ld a,(0x5C41) ; fetch MODE 0='KLC', 1='E', 2='G'.
rlc a ; double the value and set flags.
jr z,OUT_C_1 ; to OUT-C-1 if still zero ('KLC').
add a,0x43 ; add 'C' - will become 'E' if originally 1
; or 'G' if originally 2.
jr OUT_C_2 ; forward to OUT-C-2 to print.
; ---
; If mode was zero then, while printing a BASIC line, bit 2 of flags has been
; set if 'THEN' or ':' was encountered as a main character and reset otherwise.
; This is now used to determine if the 'K' cursor is to be printed but this
; transient state is also now transferred permanently to bit 3 of FLAGS
; to let the interrupt routine know how to decode the next key.
;; OUT-C-1
OUT_C_1:
ld hl,0x5C3B ; Address FLAGS
res 3,(hl) ; signal 'K' mode initially.
ld a,0x4B ; prepare letter 'K'.
bit 2,(hl) ; test FLAGS - was the
; previous main character ':' or 'THEN' ?
t/data/zx48_base.asm view on Meta::CPAN
jr nz,OUT_CH_2 ; to OUT-CH-2 with others to set 'L' mode.
push af ; save character.
ld a,(0x5C6A) ; fetch FLAGS2.
xor 0x04 ; toggle the quotes flag.
ld (0x5C6A),a ; update FLAGS2
pop af ; and restore character.
;; OUT-CH-2
OUT_CH_2:
set 2,(iy+0x01) ; update FLAGS - signal L mode if the cursor
; is next.
;; OUT-CH-3
OUT_CH_3:
rst 0x10 ; PRINT-A vectors the character to
; channel 'S', 'K', 'R' or 'P'.
ret ; return.
; -------------------------------------------
; Get starting address of line, or line after
t/data/zx48_base.asm view on Meta::CPAN
rrca ; test if quotes required.
jr nc,IN_PR_3 ; forward to IN-PR-3 if not.
ld a,0x22 ; load the '"' character
ld (de),a ; place quote in first new location at DE.
dec hl ; decrease HL - from carriage return.
ld (hl),a ; and place a quote in second location.
;; IN-PR-3
IN_PR_3:
ld (0x5C5B),hl ; set keyboard cursor K_CUR to HL
bit 7,(iy+0x37) ; test FLAGX - is this INPUT LINE ??
jr nz,IN_VAR_3 ; forward to IN-VAR-3 if so as input will
; be accepted without checking its syntax.
ld hl,(0x5C5D) ; fetch CH_ADD
push hl ; and save on stack.
ld hl,(0x5C3D) ; fetch ERR_SP
push hl ; and save on stack
;; IN-VAR-1
t/data/zx48_base.asm view on Meta::CPAN
;; IN-VAR-3
IN_VAR_3:
call EDITOR ; routine EDITOR is called for input
; when ENTER received rejoin other route but with no syntax check.
; INPUT and INPUT LINE converge here.
;; IN-VAR-4
IN_VAR_4:
ld (iy+0x22),0x00 ; set K_CUR_hi to a low value so that the cursor
; no longer appears in the input line.
call IN_CHAN_K ; routine IN-CHAN-K tests if the keyboard
; is being used for input.
jr nz,IN_VAR_5 ; forward to IN-VAR-5 if using another input
; channel.
; continue here if using the keyboard.
call ED_COPY ; routine ED-COPY overprints the edit line
; to the lower screen. The only visible
; affect is that the cursor disappears.
; if you're inputting more than one item in
; a statement then that becomes apparent.
ld bc,(0x5C82) ; fetch line and column from ECHO_E
call CL_SET ; routine CL-SET sets S-POSNL to those
; values.
; if using another input channel rejoin here.
;; IN-VAR-5
t/data/zx48_benchmark.asm view on Meta::CPAN
; own in RAM and make CHARS point to it.
RASP equ $5C38 ; Length of warning buzz.
PIP equ $5C39 ; Length of keyboard click.
ERR_NR equ $5C3A ; 1 less than the report code. Starts off at 255 (for 1)
; so PEEK 23610 gives 255.
FLAGS equ $5C3B ; Various flags to control the BASIC system.
TV_FLAG equ $5C3C ; Flags associated with the television.
ERR_SP equ $5C3D ; Address of item on machine stack to be used as
; error return.
LIST_SP equ $5C3F ; Address of return address from automatic listing.
MODE equ $5C41 ; Specifies K, L, C. E or G cursor.
NEWPPC equ $5C42 ; Line to be jumped to.
NSPPC equ $5C44 ; Statement number in line to be jumped to. Poking
; first NEWPPC and then NSPPC forces a jump to
; a specified statement in a line.
PPC equ $5C45 ; Line number of statement currently being executed.
SUBPPC equ $5C47 ; Number within line of statement being executed.
BORDCR equ $5C48 ; Border colour * 8; also contains the attributes
; normally used for the lower half of the screen.
E_PPC equ $5C49 ; Number of current line (with program cursor).
VARS equ $5C4B ; Address of variables.
DEST equ $5C4D ; Address of variable in assignment.
CHANS equ $5C4F ; Address of channel data.
CURCHL equ $5C51 ; Address of information currently being used for
; input and output.
PROG equ $5C53 ; Address of BASIC program.
NXTLIN equ $5C55 ; Address of next line in program.
DATADD equ $5C57 ; Address of terminator of last DATA item.
E_LINE equ $5C59 ; Address of command being typed in.
K_CUR equ $5C5B ; Address of cursor.
CH_ADD equ $5C5D ; Address of the next character to be interpreted:
; the character after the argument of PEEK, or
; the NEWLINE at the end of a POKE statement.
X_PTR equ $5C5F ; Address of the character after the ? marker.
WORKSP equ $5C61 ; Address of temporary work space.
STKBOT equ $5C63 ; Address of bottom of calculator stack.
STKEND equ $5C65 ; Address of start of spare space.
BREG equ $5C67 ; Calculator's b register.
MEM equ $5C68 ; Address of area used for calculator's memory.
; (Usually MEMBOT, but not always.)
t/data/zx48_benchmark.asm view on Meta::CPAN
; but is reset to KEY-INPUT
ld e, a ; save first in E
;; ED-CONTR
ED_CONTR:
call WAIT_KEY ; routine WAIT-KEY for control.
; input address will be key-next.
push de ; saved code/parameters
ld hl, (K_CUR) ; fetch address of keyboard cursor from K_CUR
res 0, (iy+MODE-IY0) ; set MODE to 'L'
call MAKE_ROOM ; routine MAKE-ROOM makes 2/3 spaces at cursor
pop bc ; restore code/parameters
inc hl ; address first location
ldi (hl), b ; place code (ink etc.)
; address next
ld (hl), c ; place possible parameter. If only one
; then DE points to this location also.
jr ADD_CH_1 ; forward to ADD-CH-1
t/data/zx48_benchmark.asm view on Meta::CPAN
; with ED-LOOP as the stacked return address.
; it is also the OUTPUT service routine for system channel 'R'.
;; ADD-CHAR
ADD_CHAR:
res 0, (iy+MODE-IY0) ; set MODE to 'L'
X0F85:
ld hl, (K_CUR) ; fetch address of keyboard cursor from K_CUR
call ONE_SPACE ; routine ONE-SPACE creates one space.
; either a continuation of above or from ED-CONTR with ED-LOOP on stack.
;; ADD-CH-1
ADD_CH_1:
ldi (de), a ; load current character to last new location.
; address next
t/data/zx48_benchmark.asm view on Meta::CPAN
;; ED-KEYS
ED_KEYS:
ld e, a ; character to E.
ld d, $00 ; prepare to add.
ld hl, ed_keys_t-$07 ; base address of editing keys table. $0F99
add hl, de ; add E
ld e, (hl) ; fetch offset to E
add hl, de ; add offset for address of handling routine.
push hl ; push the address on machine stack.
ld hl, (K_CUR) ; load address of cursor from K_CUR.
ret ; Make an indirect jump forward to routine.
; ------------------
; Editing keys table
; ------------------
; For each code in the range $07 to $0F this table contains a
; single offset byte to the routine that services that code.
; Note. for what was intended there should also have been an
; entry for chr$ 6 with offset to ed-symbol.
t/data/zx48_benchmark.asm view on Meta::CPAN
call LINE_ADDR ; routine LINE-ADDR to find address of line
; or following line if it doesn't exist.
call LINE_NO ; routine LINE-NO will get line number from
; address or previous line if at end-marker.
ld a, d ; if there is no program then DE will
or e ; contain zero so test for this.
jp z, CLEAR_SP ; jump to CLEAR-SP if so.
; Note. at this point we have a validated line number, not just an
; approximation and it would be best to update E_PPC with the true
; cursor line value which would enable the line cursor to be suppressed
; in all situations - see shortly.
push hl ; save address of line.
inc hl ; address low byte of length.
ldi c, (hl) ; transfer to C
; next to high byte
ld b, (hl) ; transfer to B.
ld hl, $000A ; an overhead of ten bytes
add hl, bc ; is added to length.
ld bc, hl ; transfer adjusted value
t/data/zx48_benchmark.asm view on Meta::CPAN
call CLEAR_SP ; routine CLEAR-SP clears editing area.
ld hl, (CURCHL) ; address CURCHL
ex (sp), hl ; swap with line address on stack
push hl ; save line address underneath
ld a, $FF ; select system channel 'R'
call CHAN_OPEN ; routine CHAN-OPEN opens it
pop hl ; drop line address
dec hl ; make it point to first byte of line num.
dec (iy+E_PPC-IY0) ; decrease E_PPC_lo to suppress line cursor.
; Note. ineffective when E_PPC is one
; greater than last line of program perhaps
; as a result of a delete.
; credit. Paul Harrison 1982.
call OUT_LINE ; routine OUT-LINE outputs the BASIC line
; to the editing area.
inc (iy+E_PPC-IY0) ; restore E_PPC_lo to the previous value.
ld hl, (E_LINE) ; address E_LINE in editing area.
inc hl ; advance
t/data/zx48_benchmark.asm view on Meta::CPAN
pop hl ; restore the address of CURCHL.
call CHAN_FLAG ; routine CHAN-FLAG sets flags for it.
ret ; RETURN to ED-LOOP.
; -------------------
; Cursor down editing
; -------------------
; The BASIC lines are displayed at the top of the screen and the user
; wishes to move the cursor down one line in edit mode.
; With INPUT LINE, this key must be used instead of entering STOP.
;; ED-DOWN
ED_DOWN:
bit 5, (iy+FLAGX-IY0) ; test FLAGX - Input Mode ?
jr nz, ED_STOP ; skip to ED-STOP if so
ld hl, E_PPC ; address E_PPC - 'current line'
call LN_FETCH ; routine LN-FETCH fetches number of next
t/data/zx48_benchmark.asm view on Meta::CPAN
;; ED-STOP
ED_STOP:
ld (iy+ERR_NR-IY0), $10 ; set ERR_NR to 'STOP in INPUT' code
jr ED_ENTER ; forward to ED-ENTER to produce error.
; -------------------
; Cursor left editing
; -------------------
; This acts on the cursor in the lower section of the screen in both
; editing and input mode.
;; ED-LEFT
ED_LEFT:
call ED_EDGE ; routine ED-EDGE moves left if possible
jr ED_CUR ; forward to ED-CUR to update K-CUR
; and return to ED-LOOP.
; --------------------
; Cursor right editing
; --------------------
; This acts on the cursor in the lower screen in both editing and input
; mode and moves it to the right.
;; ED-RIGHT
ED_RIGHT:
ld a, (hl) ; fetch addressed character.
cp $0D ; is it carriage return ?
ret z ; return if so to ED-LOOP
inc hl ; address next character
t/data/zx48_benchmark.asm view on Meta::CPAN
ED_CUR:
ld (K_CUR), hl ; update K_CUR system variable
ret ; return to ED-LOOP
; --------------
; DELETE editing
; --------------
; This acts on the lower screen and deletes the character to left of
; cursor. If control characters are present these are deleted first
; leaving the naked parameter (0-7) which appears as a '?' except in the
; case of chr$ 6 which is the comma control character. It is not mandatory
; to delete these second characters.
;; ED-DELETE
ED_DELETE:
call ED_EDGE ; routine ED-EDGE moves cursor to left.
ld bc, $0001 ; of character to be deleted.
jp RECLAIM_2 ; to RECLAIM-2 reclaim the character.
; ------------------------------------------
; Ignore next 2 codes from key-input routine
; ------------------------------------------
; Since AT and TAB cannot be entered this point is never reached
; from the keyboard. If inputting from a tape device or network then
; the control and two following characters are ignored and processing
t/data/zx48_benchmark.asm view on Meta::CPAN
pop hl ; the previous value of ERR_SP
ld (ERR_SP), hl ; is restored to ERR_SP system variable
bit 7, (iy+ERR_NR-IY0) ; is ERR_NR $FF (= 'OK') ?
ret nz ; return if so
ld sp, hl ; else put error routine on stack
ret ; and make an indirect jump to it.
; -----------------------------
; Move cursor left when editing
; -----------------------------
; This routine moves the cursor left. The complication is that it must
; not position the cursor between control codes and their parameters.
; It is further complicated in that it deals with TAB and AT characters
; which are never present from the keyboard.
; The method is to advance from the beginning of the line each time,
; jumping one, two, or three characters as necessary saving the original
; position at each jump in DE. Once it arrives at the cursor then the next
; legitimate leftmost position is in DE.
;; ED-EDGE
ED_EDGE:
scf ; carry flag must be set to call the nested
call SET_DE ; subroutine SET-DE.
; if input then DE=WORKSP
; if editing then DE=E_LINE
sbc hl, de ; subtract address from start of line
add hl, de ; and add back.
inc hl ; adjust for carry.
pop bc ; drop return address
ret c ; return to ED-LOOP if already at left
; of line.
push bc ; resave return address - ED-LOOP.
ld bc, hl ; transfer HL - cursor address
; to BC register pair.
; at this point DE addresses start of line.
;; ED-EDGE-1
ED_EDGE_1:
ld hl, de ; transfer DE - leftmost pointer
; to HL
inc hl ; address next leftmost character to
; advance position each time.
t/data/zx48_benchmark.asm view on Meta::CPAN
adc a, $00 ; will be 0 for 'tab' and 'at'.
jr nz, ED_EDGE_2 ; forward to ED-EDGE-2 if not
; HL has been incremented twice
inc hl ; increment a third time for 'at'/'tab'
;; ED-EDGE-2
ED_EDGE_2:
and a ; prepare for true subtraction
sbc hl, bc ; subtract cursor address from pointer
add hl, bc ; and add back
; Note when HL matches the cursor position BC,
; there is no carry and the previous
; position is in DE.
ex de, hl ; transfer result to DE if looping again.
; transfer DE to HL to be used as K-CUR
; if exiting loop.
jr c, ED_EDGE_1 ; back to ED-EDGE-1 if cursor not matched.
ret ; return.
; -----------------
; Cursor up editing
; -----------------
; The main screen displays part of the BASIC program and the user wishes
; to move up one line scrolling if necessary.
; This has no alternative use in input mode.
t/data/zx48_benchmark.asm view on Meta::CPAN
KEY_DONE2:
scf ; set carry flag to show a key has been found
ret ; and return.
; --------------------
; Lower screen copying
; --------------------
; This subroutine is called whenever the line in the editing area or
; input workspace is required to be printed to the lower screen.
; It is by calling this routine after any change that the cursor, for
; instance, appears to move to the left.
; Remember the edit line will contain characters and tokens
; e.g. "1000 LET a=1" is 8 characters.
;; ED-COPY
ED_COPY:
call TEMPS ; routine TEMPS sets temporary attributes.
res 3, (iy+TV_FLAG-IY0) ; update TV_FLAG - signal no change in mode
res 5, (iy+TV_FLAG-IY0) ; update TV_FLAG - signal don't clear lower
t/data/zx48_benchmark.asm view on Meta::CPAN
call SET_DE ; call routine SET-DE
; if in input DE = WORKSP
; if in edit DE = E_LINE
ex de, hl ; start address to HL
call OUT_LINE2 ; routine OUT-LINE2 outputs entire line up to
; carriage return including initial
; characterized line number when present.
ex de, hl ; transfer new address to DE
call OUT_CURS ; routine OUT-CURS considers a
; terminating cursor.
ld hl, (SPOSNL) ; fetch updated SPOSNL
ex (sp), hl ; exchange with ECHO_E on stack
ex de, hl ; transfer ECHO_E to DE
call TEMPS ; routine TEMPS to re-set attributes
; if altered.
; the lower screen was not cleared, at the outset, so if deleting then old
; text from a previous print may follow this line and requires blanking.
t/data/zx48_benchmark.asm view on Meta::CPAN
; reset MEM to its usual place in the systems variable area should it
; have been relocated to a FOR-NEXT variable. The main entry point
; SET-MIN is called at the start of the MAIN-EXEC loop and prior to
; displaying an error.
;; SET-MIN
SET_MIN:
ld hl, (E_LINE) ; fetch E_LINE
ld (hl), $0D ; insert carriage return
ld (K_CUR), hl ; make K_CUR keyboard cursor point there.
inc hl ; next location
ldi (hl), $80 ; holds end-marker $80
; next location becomes
ld (WORKSP), hl ; start of WORKSP
; This entry point is used prior to input and prior to the execution,
; or parsing, of each statement.
;; SET-WORK
t/data/zx48_benchmark.asm view on Meta::CPAN
; This routine prints a whole BASIC line and it is called
; from LIST-ALL to output the line to current channel
; and from ED-EDIT to 'sprint' the line to the edit buffer.
;; OUT-LINE
OUT_LINE:
ld bc, (E_PPC) ; fetch E_PPC the current line which may be
; unchecked and not exist.
call CP_LINES ; routine CP-LINES finds match or line after.
ld d, $3E ; prepare cursor '>' in D.
jr z, OUT_LINE1 ; to OUT-LINE1 if matched or line after.
ld de, $0000 ; put zero in D, to suppress line cursor.
rl e ; pick up carry in E if line before current
; leave E zero if same or after.
;; OUT-LINE1
OUT_LINE1:
ld (iy+BREG-IY0), e ; save flag in BREG which is spare.
ld a, (hl) ; get high byte of line number.
cp $40 ; is it too high ($2F is maximum possible) ?
pop bc ; drop the return address and
ret nc ; make an early return if so >>>
push bc ; save return address
call OUT_NUM_2 ; routine OUT-NUM-2 to print addressed number
; with leading space.
inc hl ; skip low number byte.
inc hl ; and the two
inc hl ; length bytes.
res 0, (iy+FLAGS-IY0) ; update FLAGS - signal leading space required.
ld a, d ; fetch the cursor.
and a ; test for zero.
jr z, OUT_LINE3 ; to OUT-LINE3 if zero.
rst $10 ; PRINT-A prints '>' the current line cursor.
; this entry point is called from ED-COPY
;; OUT-LINE2
OUT_LINE2:
set 0, (iy+FLAGS-IY0) ; update FLAGS - suppress leading space.
;; OUT-LINE3
t/data/zx48_benchmark.asm view on Meta::CPAN
and a ; clear the carry flag.
sbc hl, de ; test if an error address has been reached.
jr nz, OUT_LINE5 ; forward to OUT-LINE5 if not.
ld a, $3F ; load A with '?' the error marker.
call OUT_FLASH ; routine OUT-FLASH to print flashing marker.
;; OUT-LINE5
OUT_LINE5:
call OUT_CURS ; routine OUT-CURS will print the cursor if
; this is the right position.
ex de, hl ; restore address pointer to HL.
ld a, (hl) ; fetch the addressed character.
call NUMBER ; routine NUMBER skips a hidden floating
; point number if present.
inc hl ; now increment the pointer.
cp $0D ; is character end-of-line ?
jr z, OUT_LINE6 ; to OUT-LINE6, if so, as line is finished.
ex de, hl ; save the pointer in DE.
t/data/zx48_benchmark.asm view on Meta::CPAN
inc hl
inc hl
ld a, (hl) ; fetch the following character
ret ; for return value.
; --------------------------
; Print a flashing character
; --------------------------
; This subroutine is called from OUT-LINE to print a flashing error
; marker '?' or from the next routine to print a flashing cursor e.g. 'L'.
; However, this only gets called from OUT-LINE when printing the edit line
; or the input buffer to the lower screen so a direct call to $09F4 can
; be used, even though out-line outputs to other streams.
; In fact the alternate set is used for the whole routine.
;; OUT-FLASH
OUT_FLASH:
exx ; switch in alternate set
t/data/zx48_benchmark.asm view on Meta::CPAN
pop hl ; pop P_FLAG to H.
ld (iy+P_FLAG-IY0), h ; and restore system variable P_FLAG.
pop hl ; restore temporary masks
ld (ATTR_T), hl ; and restore system variables ATTR_T/MASK_T
exx ; switch back to main set
ret ; return
; ----------------
; Print the cursor
; ----------------
; This routine is called before any character is output while outputting
; a BASIC line or the input buffer. This includes listing to a printer
; or screen, copying a BASIC line to the edit buffer and printing the
; input buffer or edit buffer to the lower screen. It is only in the
; latter two cases that it has any relevance and in the last case it
; performs another very important function also.
;; OUT-CURS
OUT_CURS:
ld hl, (K_CUR) ; fetch K_CUR the current cursor address
and a ; prepare for true subtraction.
sbc hl, de ; test against pointer address in DE and
ret nz ; return if not at exact position.
; the value of MODE, maintained by KEY-INPUT, is tested and if non-zero
; then this value 'E' or 'G' will take precedence.
ld a, (MODE) ; fetch MODE 0='KLC', 1='E', 2='G'.
rlc a ; double the value and set flags.
jr z, OUT_C_1 ; to OUT-C-1 if still zero ('KLC').
add a, $43 ; add 'C' - will become 'E' if originally 1
; or 'G' if originally 2.
jr OUT_C_2 ; forward to OUT-C-2 to print.
; ---
; If mode was zero then, while printing a BASIC line, bit 2 of flags has been
; set if 'THEN' or ':' was encountered as a main character and reset otherwise.
; This is now used to determine if the 'K' cursor is to be printed but this
; transient state is also now transferred permanently to bit 3 of FLAGS
; to let the interrupt routine know how to decode the next key.
;; OUT-C-1
OUT_C_1:
ld hl, FLAGS ; Address FLAGS
res 3, (hl) ; signal 'K' mode initially.
ld a, $4B ; prepare letter 'K'.
bit 2, (hl) ; test FLAGS - was the
t/data/zx48_benchmark.asm view on Meta::CPAN
push af ; save character.
ld a, (FLAGS2) ; fetch FLAGS2.
xor $04 ; toggle the quotes flag.
ld (FLAGS2), a ; update FLAGS2
pop af ; and restore character.
;; OUT-CH-2
OUT_CH_2:
set 2, (iy+FLAGS-IY0) ; update FLAGS - signal L mode if the cursor
; is next.
;; OUT-CH-3
OUT_CH_3:
rst $10 ; PRINT-A vectors the character to
; channel 'S', 'K', 'R' or 'P'.
ret ; return.
t/data/zx48_benchmark.asm view on Meta::CPAN
jr nc, IN_PR_3 ; forward to IN-PR-3 if not.
ld a, $22 ; load the '"' character
ld (de), a ; place quote in first new location at DE.
dec hl ; decrease HL - from carriage return.
ld (hl), a ; and place a quote in second location.
;; IN-PR-3
IN_PR_3:
ld (K_CUR), hl ; set keyboard cursor K_CUR to HL
bit 7, (iy+FLAGX-IY0) ; test FLAGX - is this INPUT LINE ??
jr nz, IN_VAR_3 ; forward to IN-VAR-3 if so as input will
; be accepted without checking its syntax.
ld hl, (CH_ADD) ; fetch CH_ADD
push hl ; and save on stack.
ld hl, (ERR_SP) ; fetch ERR_SP
push hl ; and save on stack
;; IN-VAR-1
t/data/zx48_benchmark.asm view on Meta::CPAN
IN_VAR_3:
call EDITOR ; routine EDITOR is called for input
; when ENTER received rejoin other route but with no syntax check.
; INPUT and INPUT LINE converge here.
;; IN-VAR-4
IN_VAR_4:
ld (iy+$22), $00 ; set K_CUR_hi to a low value so that the cursor
; no longer appears in the input line.
call IN_CHAN_K ; routine IN-CHAN-K tests if the keyboard
; is being used for input.
jr nz, IN_VAR_5 ; forward to IN-VAR-5 if using another input
; channel.
; continue here if using the keyboard.
call ED_COPY ; routine ED-COPY overprints the edit line
; to the lower screen. The only visible
; affect is that the cursor disappears.
; if you're inputting more than one item in
; a statement then that becomes apparent.
ld bc, (ECHO_E) ; fetch line and column from ECHO_E
call CL_SET ; routine CL-SET sets S-POSNL to those
; values.
; if using another input channel rejoin here.
;; IN-VAR-5
t/data/zx81.asm view on Meta::CPAN
; ======================
; ZX-81 SYSTEM VARIABLES
; ======================
ERR_NR equ $4000 ; N1 Current report code minus one
FLAGS equ $4001 ; N1 Various flags
ERR_SP equ $4002 ; N2 Address of top of GOSUB stack
RAMTOP equ $4004 ; N2 Address of reserved area (not wiped out by NEW)
MODE equ $4006 ; N1 Current cursor mode
PPC equ $4007 ; N2 Line number of line being executed
VERSN equ $4009 ; N1 First system variable to be SAVEd
E_PPC equ $400A ; N2 Line number of line with cursor
D_FILE equ $400C ; N2 Address of start of display file
DF_CC equ $400E ; N2 Address of print position within display file
VARS equ $4010 ; N2 Address of start of variables area
DEST equ $4012 ; N2 Address of variable being assigned
E_LINE equ $4014 ; N2 Address of start of edit line
CH_ADD equ $4016 ; N2 Address of the next character to interpret
X_PTR equ $4018 ; N2 Address of char. preceding syntax error marker
STKBOT equ $401A ; N2 Address of calculator stack
STKEND equ $401C ; N2 Address of end of calculator stack
BERG equ $401E ; N1 Used by floating point calculator
t/data/zx81.asm view on Meta::CPAN
;
; ---
;
defb $FF ; unused location.
;
; ---------------------------------
; THE 'COLLECT A CHARACTER' RESTART
; ---------------------------------
; The character addressed by the system variable CH_ADD is fetched and if it
; is a non-space, non-cursor character it is returned else CH_ADD is
; incremented and the new addressed character tested until it is not a space.
;; GET-CHAR
GET_CHAR:
ld hl, (CH_ADD) ; set HL to character address CH_ADD.
ld a, (hl) ; fetch addressed character to A.
;
;; TEST-SP
t/data/zx81.asm view on Meta::CPAN
and a ; test for space.
ret nz ; return if not a space
;
nop ; else trickle through
nop ; to the next routine.
;
; ------------------------------------
; THE 'COLLECT NEXT CHARACTER' RESTART
; ------------------------------------
; The character address in incremented and the new addressed character is
; returned if not a space, or cursor, else the process is repeated.
;; NEXT-CHAR
NEXT_CHAR:
call CH_ADD_1 ; routine CH-ADD+1 gets next immediate
; character.
jr TEST_SP ; back to TEST-SP.
;
; ---
t/data/zx81.asm view on Meta::CPAN
; generated by the HALT that cause the Refresh value to rise from $E0 to $FF,
; triggering an Interrupt on the next transition.
; This works happily for all display lines between these extremes and the
; generation of the 32 character, 1 pixel high, line will always take 128
; clock cycles.
; ---------------------------------
; THE 'INCREMENT CH-ADD' SUBROUTINE
; ---------------------------------
; This is the subroutine that increments the character address system variable
; and returns if it is not the cursor character. The ZX81 has an actual
; character at the cursor position rather than a pointer system variable
; as is the case with prior and subsequent ZX computers.
;; CH-ADD+1
CH_ADD_1:
ld hl, (CH_ADD) ; fetch character address to CH_ADD.
;
;; TEMP-PTR1
TEMP_PTR1:
inc hl ; address next immediate location.
;
;; TEMP-PTR2
TEMP_PTR2:
ld (CH_ADD), hl ; update system variable CH_ADD.
;
ld a, (hl) ; fetch the character.
cp $7F ; compare to cursor character.
ret nz ; return if not the cursor.
;
jr TEMP_PTR1 ; back for next character to TEMP-PTR1.
;
; --------------------
; THE 'ERROR-2' BRANCH
; --------------------
; This is a continuation of the error restart.
; If the error occurred in runtime then the error stack pointer will probably
; lead to an error report being printed unless it occurred during input.
t/data/zx81.asm view on Meta::CPAN
defb $E2 ; LLIST
defb $C0 ; ""
defb $D9 ; OR
defb $E0 ; STEP
defb $DB ; <=
defb $DD ; <>
defb $75 ; EDIT
defb $DA ; AND
defb $DE ; THEN
defb $DF ; TO
defb $72 ; cursor-left
defb $77 ; RUBOUT
defb $74 ; GRAPHICS
defb $73 ; cursor-right
defb $70 ; cursor-up
defb $71 ; cursor-down
defb $0B ; "
defb $11 ; )
defb $10 ; (
defb $0D ; $
defb $DC ; >=
defb $79 ; FUNCTION
defb $14 ; =
defb $15 ; +
defb $16 ; -
defb $D8 ; **
t/data/zx81.asm view on Meta::CPAN
;
ld (VARS), hl ; set system variable VARS to next location
;
call CLEAR ; routine CLEAR sets $80 end-marker and the
; dynamic memory pointers E_LINE, STKBOT and
; STKEND.
;
;; N/L-ONLY
N_L_ONLY:
call CURSOR_IN ; routine CURSOR-IN inserts the cursor and
; end-marker in the Edit Line also setting
; size of lower display to two lines.
;
call SLOW_FAST ; routine SLOW/FAST selects COMPUTE and DISPLAY
;
; ---------------------------
; THE 'BASIC LISTING' SECTION
; ---------------------------
;
;
t/data/zx81.asm view on Meta::CPAN
;
ld (hl), d ;
dec hl ;
ld (hl), e ;
jr UPPER ; to UPPER
;
; ----------------------------
; THE 'EDIT LINE COPY' SECTION
; ----------------------------
; This routine sets the edit line to just the cursor when
; 1) There is not enough memory to edit a BASIC line.
; 2) The edit key is used during input.
; The entry point LOWER
;; EDIT-INP
EDIT_INP:
call CURSOR_IN ; routine CURSOR-IN sets cursor only edit line.
;
; ->
;; LOWER
LOWER:
ld hl, (E_LINE) ; fetch edit line start from E_LINE.
;
;; EACH-CHAR
t/data/zx81.asm view on Meta::CPAN
;; END-LINE
END_LINE:
cp $76 ;
inc hl ;
jr nz, EACH_CHAR ; to EACH-CHAR
;
;; EDIT-LINE
EDIT_LINE:
call CURSOR ; routine CURSOR sets cursor K or L.
;
;; EDIT-ROOM
EDIT_ROOM:
call LINE_ENDS ; routine LINE-ENDS
ld hl, (E_LINE) ; sv E_LINE_lo
ld (iy+ERR_NR-IY0), $FF ; sv ERR_NR
call COPY_LINE ; routine COPY-LINE
bit 7, (iy+ERR_NR-IY0) ; sv ERR_NR
jr nz, DISPLAY_6 ; to DISPLAY-6
t/data/zx81.asm view on Meta::CPAN
ld hl, EDIT_INP ; Address: EDIT-INP
push hl ; ** is pushed as an error looping address.
;
bit 5, (iy+FLAGX-IY0) ; test FLAGX
ret nz ; indirect jump if in input mode
; to L046F, EDIT-INP (begin again).
;
;
ld hl, (E_LINE) ; fetch E_LINE
ld (DF_CC), hl ; and use to update the screen cursor DF_CC
;
; so now RST $10 will print the line numbers to the edit line instead of screen.
; first make sure that no newline/out of screen can occur while sprinting the
; line numbers to the edit line.
ld hl, $1821 ; prepare line 0, column 0.
ld (S_POSN), hl ; update S_POSN with these dummy values.
;
ld hl, (E_PPC) ; fetch current line from E_PPC may be a
; non-existent line e.g. last line deleted.
t/data/zx81.asm view on Meta::CPAN
;
dec hl ; point to high byte.
call OUT_NO ; routine OUT-NO writes number to edit line.
;
inc hl ; point to length bytes.
ld c, (hl) ; low byte to C.
inc hl ;
ld b, (hl) ; high byte to B.
;
inc hl ; point to first character in line.
ld de, (DF_CC) ; fetch display file cursor DF_CC
;
ld a, $7F ; prepare the cursor character.
ld (de), a ; and insert in edit line.
inc de ; increment intended destination.
;
push hl ; * save start of BASIC.
;
ld hl, $001D ; set an overhead of 29 bytes.
add hl, de ; add in the address of cursor.
add hl, bc ; add the length of the line.
sbc hl, sp ; subtract the stack pointer.
;
pop hl ; * restore pointer to start of BASIC.
;
ret nc ; return if not enough room to L046F EDIT-INP.
; the edit key appears not to work.
;
ldir ; else copy bytes from program to edit line.
; Note. hidden floating point forms are also
t/data/zx81.asm view on Meta::CPAN
rst $10 ; PRINT-A
jr MORE_LINE ; to MORE-LINE
;
; ---
;; OUT-CURS
OUT_CURS:
ld a, (MODE) ; Fetch value of system variable MODE
ld b, $AB ; Prepare an inverse [F] for function cursor.
;
and a ; Test for zero -
jr nz, FLAGS_2 ; forward if not to FLAGS-2
;
ld a, (FLAGS) ; Fetch system variable FLAGS.
ld b, $B0 ; Prepare an inverse [K] for keyword cursor.
;
;; FLAGS-2
FLAGS_2:
rra ; 00000?00 -> 000000?0
rra ; 000000?0 -> 0000000?
and $01 ; 0000000? 0000000x
;
add a, b ; Possibly [F] -> [G] or [K] -> [L]
;
t/data/zx81.asm view on Meta::CPAN
;; SET-STK-E
SET_STK_E:
ld (STKEND), hl ; sv STKEND
ret ;
; -----------------------
; THE 'CURSOR-IN' ROUTINE
; -----------------------
; This routine is called to set the edit line to the minimum cursor/newline
; and to set STKEND, the start of free space, at the next position.
;; CURSOR-IN
CURSOR_IN:
ld hl, (E_LINE) ; fetch start of edit line from E_LINE
ld (hl), $7F ; insert cursor character
;
inc hl ; point to next location.
ld (hl), $76 ; insert NEWLINE character
inc hl ; point to next free location.
;
ld (iy+DF_SZ-IY0), $02 ; set lower screen display file size DF_SZ
;
jr SET_STK_B ; exit via SET-STK-B above
;
t/data/zx81.ctl view on Meta::CPAN
0017:B
0017-0017 FF :B
:; unused location.
:;
0018:C
:#; ---------------------------------
:#; THE 'COLLECT A CHARACTER' RESTART
:#; ---------------------------------
:#; The character addressed by the system variable CH_ADD is fetched and if it
:#; is a non-space, non-cursor character it is returned else CH_ADD is
:#; incremented and the new addressed character tested until it is not a space.
:#
:#;; GET-CHAR
0018 2A1640 ld hl, ($4016) :C GET_CHAR
:; set HL to character address CH_ADD.
001B:C
001B 7E ld a, (hl) :C
:; fetch addressed character to A.
:;
t/data/zx81.ctl view on Meta::CPAN
001F:C
001F 00 nop :C
:; to the next routine.
:;
0020:C
:#; ------------------------------------
:#; THE 'COLLECT NEXT CHARACTER' RESTART
:#; ------------------------------------
:#; The character address in incremented and the new addressed character is
:#; returned if not a space, or cursor, else the process is repeated.
:#
:#;; NEXT-CHAR
0020 CD4900 call $0049 :C NEXT_CHAR
:; routine CH-ADD+1 gets next immediate
:; character.
0023:C
0023 18F7 jr $001C :C
:; back to TEST-SP.
:;
t/data/zx81.ctl view on Meta::CPAN
:#; generated by the HALT that cause the Refresh value to rise from $E0 to $FF,
:#; triggering an Interrupt on the next transition.
:#; This works happily for all display lines between these extremes and the
:#; generation of the 32 character, 1 pixel high, line will always take 128
:#; clock cycles.
:#
:#; ---------------------------------
:#; THE 'INCREMENT CH-ADD' SUBROUTINE
:#; ---------------------------------
:#; This is the subroutine that increments the character address system variable
:#; and returns if it is not the cursor character. The ZX81 has an actual
:#; character at the cursor position rather than a pointer system variable
:#; as is the case with prior and subsequent ZX computers.
:#
:#;; CH-ADD+1
0049 2A1640 ld hl, ($4016) :C CH_ADD_1
:; fetch character address to CH_ADD.
:;
004C:C
:#;; TEMP-PTR1
004C 23 inc hl :C TEMP_PTR1
t/data/zx81.ctl view on Meta::CPAN
004D 221640 ld ($4016), hl :C TEMP_PTR2
:; update system variable CH_ADD.
:;
0050:C
0050 7E ld a, (hl) :C
:; fetch the character.
0051:C
0051 FE7F cp $7F :C
:; compare to cursor character.
0053:C
0053 C0 ret nz :C
:; return if not the cursor.
:;
0054:C
0054 18F6 jr $004C :C
:; back for next character to TEMP-PTR1.
:;
0056:C
:#; --------------------
:#; THE 'ERROR-2' BRANCH
t/data/zx81.ctl view on Meta::CPAN
00B5:B
00B5-00B5 DE :B
:; THEN
00B6:B
00B6-00B6 DF :B
:; TO
00B7:B
00B7-00B7 72 :B
:; cursor-left
00B8:B
00B8-00B8 77 :B
:; RUBOUT
00B9:B
00B9-00B9 74 :B
:; GRAPHICS
00BA:B
00BA-00BA 73 :B
:; cursor-right
00BB:B
00BB-00BB 70 :B
:; cursor-up
00BC:B
00BC-00BC 71 :B
:; cursor-down
00BD:B
00BD-00BD 0B :B
:; "
00BE:B
00BE-00BE 11 :B
:; )
00BF:B
t/data/zx81.ctl view on Meta::CPAN
0410:C
0410 CD9A14 call $149A :C
:; routine CLEAR sets $80 end-marker and the
:; dynamic memory pointers E_LINE, STKBOT and
:; STKEND.
:;
0413:C
:#;; N/L-ONLY
0413 CDAD14 call $14AD :C N_L_ONLY
:; routine CURSOR-IN inserts the cursor and
:; end-marker in the Edit Line also setting
:; size of lower display to two lines.
:;
0416:C
0416 CD0702 call $0207 :C
:; routine SLOW/FAST selects COMPUTE and DISPLAY
:;
0419:C
t/data/zx81.ctl view on Meta::CPAN
046D:C
046D 18AA jr $0419 :C
:; to UPPER
:;
046F:C
:#; ----------------------------
:#; THE 'EDIT LINE COPY' SECTION
:#; ----------------------------
:#; This routine sets the edit line to just the cursor when
:#; 1) There is not enough memory to edit a BASIC line.
:#; 2) The edit key is used during input.
:#; The entry point LOWER
:#
:#
:#;; EDIT-INP
046F CDAD14 call $14AD :C EDIT_INP
:; routine CURSOR-IN sets cursor only edit line.
:;
0472:C
:#; ->
:#
:#;; LOWER
0472 2A1440 ld hl, ($4014) :C LOWER
:; fetch edit line start from E_LINE.
:;
t/data/zx81.ctl view on Meta::CPAN
:;
0485:C
0485 20EE jr nz, $0475 :C
:; to EACH-CHAR
:;
0487:C
:#;; EDIT-LINE
0487 CD3705 call $0537 :C EDIT_LINE
:; routine CURSOR sets cursor K or L.
:;
048A:C
:#;; EDIT-ROOM
048A CD1F0A call $0A1F :C EDIT_ROOM
:; routine LINE-ENDS
048D:C
048D 2A1440 ld hl, ($4014) :C
:; sv E_LINE_lo
t/data/zx81.ctl view on Meta::CPAN
:;
05D0:C
:#;
:#
05D0 2A1440 ld hl, ($4014) :C
:; fetch E_LINE
05D3:C
05D3 220E40 ld ($400E), hl :C
:; and use to update the screen cursor DF_CC
:;
05D6:C
:#; so now RST $10 will print the line numbers to the edit line instead of screen.
:#; first make sure that no newline/out of screen can occur while sprinting the
:#; line numbers to the edit line.
:#
05D6 212118 ld hl, $1821 :C
:; prepare line 0, column 0.
t/data/zx81.ctl view on Meta::CPAN
05EF 46 ld b, (hl) :C
:; high byte to B.
:;
05F0:C
05F0 23 inc hl :C
:; point to first character in line.
05F1:C
05F1 ED5B0E40 ld de, ($400E) :C
:; fetch display file cursor DF_CC
:;
05F5:C
05F5 3E7F ld a, $7F :C
:; prepare the cursor character.
05F7:C
05F7 12 ld (de), a :C
:; and insert in edit line.
05F8:C
05F8 13 inc de :C
:; increment intended destination.
:;
t/data/zx81.ctl view on Meta::CPAN
05F9 E5 push hl :C
:; * save start of BASIC.
:;
05FA:C
05FA 211D00 ld hl, $001D :C
:; set an overhead of 29 bytes.
05FD:C
05FD 19 add hl, de :C
:; add in the address of cursor.
05FE:C
05FE 09 add hl, bc :C
:; add the length of the line.
05FF:C
05FF ED72 sbc hl, sp :C
:; subtract the stack pointer.
:;
t/data/zx81.ctl view on Meta::CPAN
079D:C
:#; ---
:#
:#;; OUT-CURS
079D 3A0640 ld a, ($4006) :C OUT_CURS
:; Fetch value of system variable MODE
07A0:C
07A0 06AB ld b, $AB :C
:; Prepare an inverse [F] for function cursor.
:;
07A2:C
07A2 A7 and a :C
:; Test for zero -
07A3:C
07A3 2005 jr nz, $07AA :C
:; forward if not to FLAGS-2
:;
07A5:C
07A5 3A0140 ld a, ($4001) :C
:; Fetch system variable FLAGS.
07A8:C
07A8 06B0 ld b, $B0 :C
:; Prepare an inverse [K] for keyword cursor.
:;
07AA:C
:#;; FLAGS-2
07AA 1F rra :C FLAGS_2
:; 00000?00 -> 000000?0
07AB:C
07AB 1F rra :C
:; 000000?0 -> 0000000?
t/data/zx81.ctl view on Meta::CPAN
14AC:C
14AC C9 ret :C
:;
:;
14AD:C
:#; -----------------------
:#; THE 'CURSOR-IN' ROUTINE
:#; -----------------------
:#; This routine is called to set the edit line to the minimum cursor/newline
:#; and to set STKEND, the start of free space, at the next position.
:#
:#;; CURSOR-IN
14AD 2A1440 ld hl, ($4014) :C CURSOR_IN
:; fetch start of edit line from E_LINE
14B0:C
14B0 367F ld (hl), $7F :C
:; insert cursor character
:;
14B2:C
14B2 23 inc hl :C
:; point to next location.
14B3:C
14B3 3676 ld (hl), $76 :C
:; insert NEWLINE character
t/data/zx81_sysvars.ctl view on Meta::CPAN
:<; ======================
:<
:<
4000 :IY
4000 := ERR_NR ; N1 Current report code minus one
4001 := FLAGS ; N1 Various flags
4002 := ERR_SP ; N2 Address of top of GOSUB stack
4004 := RAMTOP ; N2 Address of reserved area (not wiped out by NEW)
4006 := MODE ; N1 Current cursor mode
4007 := PPC ; N2 Line number of line being executed
4009 := VERSN ; N1 First system variable to be SAVEd
400A := E_PPC ; N2 Line number of line with cursor
400C := D_FILE ; N2 Address of start of display file
400E := DF_CC ; N2 Address of print position within display file
4010 := VARS ; N2 Address of start of variables area
4012 := DEST ; N2 Address of variable being assigned
4014 := E_LINE ; N2 Address of start of edit line
4016 := CH_ADD ; N2 Address of the next character to interpret
4018 := X_PTR ; N2 Address of char. preceding syntax error marker
401A := STKBOT ; N2 Address of calculator stack
401C := STKEND ; N2 Address of end of calculator stack
401E := BERG ; N1 Used by floating point calculator
t/data/zx81_version_2_rom_source.asm view on Meta::CPAN
JP L07F5 ; jump forward to PRINT-SP.
; ---
DEFB $FF ; unused location.
; ---------------------------------
; THE 'COLLECT A CHARACTER' RESTART
; ---------------------------------
; The character addressed by the system variable CH_ADD is fetched and if it
; is a non-space, non-cursor character it is returned else CH_ADD is
; incremented and the new addressed character tested until it is not a space.
;; GET-CHAR
L0018: LD HL,($4016) ; set HL to character address CH_ADD.
LD A,(HL) ; fetch addressed character to A.
;; TEST-SP
L001C: AND A ; test for space.
RET NZ ; return if not a space
NOP ; else trickle through
NOP ; to the next routine.
; ------------------------------------
; THE 'COLLECT NEXT CHARACTER' RESTART
; ------------------------------------
; The character address in incremented and the new addressed character is
; returned if not a space, or cursor, else the process is repeated.
;; NEXT-CHAR
L0020: CALL L0049 ; routine CH-ADD+1 gets next immediate
; character.
JR L001C ; back to TEST-SP.
; ---
DEFB $FF, $FF, $FF ; unused locations.
t/data/zx81_version_2_rom_source.asm view on Meta::CPAN
; generated by the HALT that cause the Refresh value to rise from $E0 to $FF,
; triggering an Interrupt on the next transition.
; This works happily for all display lines between these extremes and the
; generation of the 32 character, 1 pixel high, line will always take 128
; clock cycles.
; ---------------------------------
; THE 'INCREMENT CH-ADD' SUBROUTINE
; ---------------------------------
; This is the subroutine that increments the character address system variable
; and returns if it is not the cursor character. The ZX81 has an actual
; character at the cursor position rather than a pointer system variable
; as is the case with prior and subsequent ZX computers.
;; CH-ADD+1
L0049: LD HL,($4016) ; fetch character address to CH_ADD.
;; TEMP-PTR1
L004C: INC HL ; address next immediate location.
;; TEMP-PTR2
L004D: LD ($4016),HL ; update system variable CH_ADD.
LD A,(HL) ; fetch the character.
CP $7F ; compare to cursor character.
RET NZ ; return if not the cursor.
JR L004C ; back for next character to TEMP-PTR1.
; --------------------
; THE 'ERROR-2' BRANCH
; --------------------
; This is a continuation of the error restart.
; If the error occurred in runtime then the error stack pointer will probably
; lead to an error report being printed unless it occurred during input.
; If the error occurred when checking syntax then the error stack pointer
t/data/zx81_version_2_rom_source.asm view on Meta::CPAN
DEFB $E2 ; LLIST
DEFB $C0 ; ""
DEFB $D9 ; OR
DEFB $E0 ; STEP
DEFB $DB ; <=
DEFB $DD ; <>
DEFB $75 ; EDIT
DEFB $DA ; AND
DEFB $DE ; THEN
DEFB $DF ; TO
DEFB $72 ; cursor-left
DEFB $77 ; RUBOUT
DEFB $74 ; GRAPHICS
DEFB $73 ; cursor-right
DEFB $70 ; cursor-up
DEFB $71 ; cursor-down
DEFB $0B ; "
DEFB $11 ; )
DEFB $10 ; (
DEFB $0D ; $
DEFB $DC ; >=
DEFB $79 ; FUNCTION
DEFB $14 ; =
DEFB $15 ; +
DEFB $16 ; -
DEFB $D8 ; **
t/data/zx81_version_2_rom_source.asm view on Meta::CPAN
INC HL ; point to next location.
DJNZ L0408 ; loop back for all twenty five to LINE
LD ($4010),HL ; set system variable VARS to next location
CALL L149A ; routine CLEAR sets $80 end-marker and the
; dynamic memory pointers E_LINE, STKBOT and
; STKEND.
;; N/L-ONLY
L0413: CALL L14AD ; routine CURSOR-IN inserts the cursor and
; end-marker in the Edit Line also setting
; size of lower display to two lines.
CALL L0207 ; routine SLOW/FAST selects COMPUTE and DISPLAY
; ---------------------------
; THE 'BASIC LISTING' SECTION
; ---------------------------
;
;
t/data/zx81_version_2_rom_source.asm view on Meta::CPAN
JR NZ,L0472 ; forward to LOWER
LD (HL),D ;
DEC HL ;
LD (HL),E ;
JR L0419 ; to UPPER
; ----------------------------
; THE 'EDIT LINE COPY' SECTION
; ----------------------------
; This routine sets the edit line to just the cursor when
; 1) There is not enough memory to edit a BASIC line.
; 2) The edit key is used during input.
; The entry point LOWER
;; EDIT-INP
L046F: CALL L14AD ; routine CURSOR-IN sets cursor only edit line.
; ->
;; LOWER
L0472: LD HL,($4014) ; fetch edit line start from E_LINE.
;; EACH-CHAR
L0475: LD A,(HL) ; fetch a character from edit line.
CP $7E ; compare to the number marker.
JR NZ,L0482 ; forward if not to END-LINE
t/data/zx81_version_2_rom_source.asm view on Meta::CPAN
JR L0475 ; back to EACH-CHAR
; ---
;; END-LINE
L0482: CP $76 ;
INC HL ;
JR NZ,L0475 ; to EACH-CHAR
;; EDIT-LINE
L0487: CALL L0537 ; routine CURSOR sets cursor K or L.
;; EDIT-ROOM
L048A: CALL L0A1F ; routine LINE-ENDS
LD HL,($4014) ; sv E_LINE_lo
LD (IY+$00),$FF ; sv ERR_NR
CALL L0766 ; routine COPY-LINE
BIT 7,(IY+$00) ; sv ERR_NR
JR NZ,L04C1 ; to DISPLAY-6
LD A,($4022) ; sv DF_SZ
t/data/zx81_version_2_rom_source.asm view on Meta::CPAN
LD HL,L046F ; Address: EDIT-INP
PUSH HL ; ** is pushed as an error looping address.
BIT 5,(IY+$2D) ; test FLAGX
RET NZ ; indirect jump if in input mode
; to L046F, EDIT-INP (begin again).
;
LD HL,($4014) ; fetch E_LINE
LD ($400E),HL ; and use to update the screen cursor DF_CC
; so now RST $10 will print the line numbers to the edit line instead of screen.
; first make sure that no newline/out of screen can occur while sprinting the
; line numbers to the edit line.
LD HL,$1821 ; prepare line 0, column 0.
LD ($4039),HL ; update S_POSN with these dummy values.
LD HL,($400A) ; fetch current line from E_PPC may be a
; non-existent line e.g. last line deleted.
t/data/zx81_version_2_rom_source.asm view on Meta::CPAN
DEC HL ; point to high byte.
CALL L0AA5 ; routine OUT-NO writes number to edit line.
INC HL ; point to length bytes.
LD C,(HL) ; low byte to C.
INC HL ;
LD B,(HL) ; high byte to B.
INC HL ; point to first character in line.
LD DE,($400E) ; fetch display file cursor DF_CC
LD A,$7F ; prepare the cursor character.
LD (DE),A ; and insert in edit line.
INC DE ; increment intended destination.
PUSH HL ; * save start of BASIC.
LD HL,$001D ; set an overhead of 29 bytes.
ADD HL,DE ; add in the address of cursor.
ADD HL,BC ; add the length of the line.
SBC HL,SP ; subtract the stack pointer.
POP HL ; * restore pointer to start of BASIC.
RET NC ; return if not enough room to L046F EDIT-INP.
; the edit key appears not to work.
LDIR ; else copy bytes from program to edit line.
; Note. hidden floating point forms are also
t/data/zx81_version_2_rom_source.asm view on Meta::CPAN
;; NOT-TOKEN
L079A: RST 10H ; PRINT-A
JR L076D ; to MORE-LINE
; ---
;; OUT-CURS
L079D: LD A,($4006) ; Fetch value of system variable MODE
LD B,$AB ; Prepare an inverse [F] for function cursor.
AND A ; Test for zero -
JR NZ,L07AA ; forward if not to FLAGS-2
LD A,($4001) ; Fetch system variable FLAGS.
LD B,$B0 ; Prepare an inverse [K] for keyword cursor.
;; FLAGS-2
L07AA: RRA ; 00000?00 -> 000000?0
RRA ; 000000?0 -> 0000000?
AND $01 ; 0000000? 0000000x
ADD A,B ; Possibly [F] -> [G] or [K] -> [L]
CALL L07F5 ; routine PRINT-SP prints character
JR L076D ; back to MORE-LINE
t/data/zx81_version_2_rom_source.asm view on Meta::CPAN
;
;; SET-STK-E
L14A9: LD ($401C),HL ; sv STKEND
RET ;
; -----------------------
; THE 'CURSOR-IN' ROUTINE
; -----------------------
; This routine is called to set the edit line to the minimum cursor/newline
; and to set STKEND, the start of free space, at the next position.
;; CURSOR-IN
L14AD: LD HL,($4014) ; fetch start of edit line from E_LINE
LD (HL),$7F ; insert cursor character
INC HL ; point to next location.
LD (HL),$76 ; insert NEWLINE character
INC HL ; point to next free location.
LD (IY+$22),$02 ; set lower screen display file size DF_SZ
JR L14A6 ; exit via SET-STK-B above
; ------------------------
t/dis_zx48.t view on Meta::CPAN
"own in RAM and make CHARS point to it.");
$self->labels->add(0x5C38, 'RASP' )->comment("Length of warning buzz.");
$self->labels->add(0x5C39, 'PIP' )->comment("Length of keyboard click.");
$self->labels->add(0x5C3A, 'ERR_NR' )->comment("1 less than the report code. Starts off at 255 (for 1)\n".
"so PEEK 23610 gives 255.");
$self->labels->add(0x5C3B, 'FLAGS' )->comment("Various flags to control the BASIC system.");
$self->labels->add(0x5C3C, 'TV_FLAG' )->comment("Flags associated with the television.");
$self->labels->add(0x5C3D, 'ERR_SP' )->comment("Address of item on machine stack to be used as\n".
"error return.");
$self->labels->add(0x5C3F, 'LIST_SP' )->comment("Address of return address from automatic listing.");
$self->labels->add(0x5C41, 'MODE' )->comment("Specifies K, L, C. E or G cursor.");
$self->labels->add(0x5C42, 'NEWPPC' )->comment("Line to be jumped to.");
$self->labels->add(0x5C44, 'NSPPC' )->comment("Statement number in line to be jumped to. Poking\n".
"first NEWPPC and then NSPPC forces a jump to\n".
"a specified statement in a line.");
$self->labels->add(0x5C45, 'PPC' )->comment("Line number of statement currently being executed.");
$self->labels->add(0x5C47, 'SUBPPC' )->comment("Number within line of statement being executed.");
$self->labels->add(0x5C48, 'BORDCR' )->comment("Border colour * 8; also contains the attributes\n".
"normally used for the lower half of the screen.");
$self->labels->add(0x5C49, 'E_PPC' )->comment("Number of current line (with program cursor).");
$self->labels->add(0x5C4B, 'VARS' )->comment("Address of variables.");
$self->labels->add(0x5C4D, 'DEST' )->comment("Address of variable in assignment.");
$self->labels->add(0x5C4F, 'CHANS' )->comment("Address of channel data.");
$self->labels->add(0x5C51, 'CURCHL' )->comment("Address of information currently being used for\n".
"input and output.");
$self->labels->add(0x5C53, 'PROG' )->comment("Address of BASIC program.");
$self->labels->add(0x5C55, 'NXTLIN' )->comment("Address of next line in program.");
$self->labels->add(0x5C57, 'DATADD' )->comment("Address of terminator of last DATA item.");
$self->labels->add(0x5C59, 'E_LINE' )->comment("Address of command being typed in.");
$self->labels->add(0x5C5B, 'K_CUR' )->comment("Address of cursor.");
$self->labels->add(0x5C5D, 'CH_ADD' )->comment("Address of the next character to be interpreted:\n".
"the character after the argument of PEEK, or\n".
"the NEWLINE at the end of a POKE statement.");
$self->labels->add(0x5C5F, 'X_PTR' )->comment("Address of the character after the ? marker.");
$self->labels->add(0x5C61, 'WORKSP' )->comment("Address of temporary work space.");
$self->labels->add(0x5C63, 'STKBOT' )->comment("Address of bottom of calculator stack.");
$self->labels->add(0x5C65, 'STKEND' )->comment("Address of start of spare space.");
$self->labels->add(0x5C67, 'BREG' )->comment("Calculator's b register.");
$self->labels->add(0x5C68, 'MEM' )->comment("Address of area used for calculator's memory.\n".
"(Usually MEMBOT, but not always.)");
( run in 0.335 second using v1.01-cache-2.11-cpan-4d50c553e7e )