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;   added inline divide by 10 to prnum:.
;   fixed statement delimiter not overriding mismatched
;     parentheses.
;   line numbers >= 65280 are now reserved for the
;     following fast return & goto features.
;   added a gosub stack, depth = 16 address words.
;     {==...} is a gosub and pushes the return address
;     of the next line.
;     {#==} is a return and pops the address when the
;     result is the special line numer asigned to {=}.
;   added a 31 line addresses acronym label array.
;     lowercase characters and symbols in the $60-$7e
;     range are used to address the array. the array
;     is populated with the address of a line when a
;     character in the allowed range preceeds the line
;     number.
This commit is contained in:
Klaus2m5 2015-11-16 21:15:02 +01:00
parent ff26f67cf7
commit fbd001c897
1 changed files with 414 additions and 235 deletions
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649
vtl02sg.a65
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@ -180,12 +180,32 @@
; mainloop uses inline code to advance to next ; mainloop uses inline code to advance to next
; sequential program line. ; sequential program line.
; find: is now only used for true branches. ; find: is now only used for true branches.
; added statement delimiter allowing multi statement ; added a statement delimiter {;} allowing multi
; lines. branch to same line is now allowed. ; statement lines.
; added decimal to binary conversion on line entry. ; branch to same line is now allowed.
; {?="..."} & unmatched {)} (used for comments) can
; not be continued.
; added decimal to binary conversion on line entry
; avoiding the runtime conversion.
; abbreviated getting a simple variable in getval:. ; abbreviated getting a simple variable in getval:.
; bypassed setting a simple variable in exec:. ; bypassed setting a simple variable in exec:.
; ; added inline divide by 10 to prnum:.
; fixed statement delimiter not overriding mismatched
; parentheses.
; line numbers >= 65280 are now reserved for the
; following fast return & goto features.
; added a gosub stack, depth = 16 address words.
; {==...} is a gosub and pushes the return address
; of the next line.
; {#==} is a return and pops the address when the
; result is the special line numer asigned to {=}.
; added a 31 line addresses acronym label array.
; lowercase characters and symbols in the $60-$7e
; range are used to address the array. the array
; is populated with the address of a line when a
; character in the allowed range preceeds the line
; number.
;
;-----------------------------------------------------; ;-----------------------------------------------------;
; VTL02C variables occupy RAM addresses $0080 to $00ff, ; VTL02C variables occupy RAM addresses $0080 to $00ff,
; and are little-endian, in the 6502 tradition. ; and are little-endian, in the 6502 tradition.
@ -203,7 +223,8 @@ at = $80 ; {@}* internal pointer / mem byte
; VTL02C standard user variable space ; VTL02C standard user variable space
; {A B C .. X Y Z [ \ ] ^ _} ; {A B C .. X Y Z [ \ ] ^ _}
; VTL02C system variable space ; VTL02C system variable space
space = $c0 ; { }* temp / Starting with VTL02B: space = $c0 ; { }* gosub stack /
; Starting with VTL02B:
; the space character is no ; the space character is no
; longer a valid user variable ; longer a valid user variable
; nor a "valid" binary operator. ; nor a "valid" binary operator.
@ -222,21 +243,20 @@ lparen = $d0 ; {(}* old line # / begin sub-exp
rparen = $d2 ; {)}* temp storage / end sub-exp rparen = $d2 ; {)}* temp storage / end sub-exp
star = $d4 ; {*} pointer to end of free mem star = $d4 ; {*} pointer to end of free mem
; $d6 ; {+ , - .} valid variables ; $d6 ; {+ , - .} valid variables
; $fe ; {/} counting 10ms tick timer ; (1) $fe ; {/} 10ms count up timer
; Interpreter argument stack space ; Interpreter argument stack space
arg = $e0 ; {0 1 2 3 4 5 6 7 8 9 :}* arg = $e0 ; {0 1 2 3 4 5 6 7 8 9 :}*
; Rarely used variables and argument stack overflow ; Rarely used variables and argument stack overflow
; $f6 ; {;}* valid user variable / semico = $f6 ; {;}* statement delimiter
; statement separator
lthan = $f8 ; {<}* user memory byte pointer lthan = $f8 ; {<}* user memory byte pointer
; = $fa ; {=}* valid user variable equal = $fa ; {=}* temp / gosub & return addr.
gthan = $fc ; {>}* temp / call ML subroutine gthan = $fc ; {>}* temp / call ML subroutine
ques = $fe ; {?}* temp / terminal i/o ques = $fe ; {?}* temp / terminal i/o
; ;
nulstk = $01ff ; system stack resides in page 1 nulstk = $01ff ; system stack resides in page 1
; additional configurable variables and operators ; (1) additional configurable variables and operators
timr_var = '/' ; 10 ms count up variable timr_var = '/' ; 10 ms count up variable
stmntdlm = ';' ; statement delimiter timr_adr = timr_var*2|$80
;-----------------------------------------------------; ;-----------------------------------------------------;
; Equates for a 48K+ Apple 2 (original, +, e, c, gs) ; Equates for a 48K+ Apple 2 (original, +, e, c, gs)
;ESC = 27 ; "Cancel current input line" key ;ESC = 27 ; "Cancel current input line" key
@ -256,10 +276,12 @@ ESC = 27 ; "Cancel current input line" key
BS = 8 ; "Delete last keypress" key BS = 8 ; "Delete last keypress" key
OP_OR = '|' ; Bit-wise OR operator OP_OR = '|' ; Bit-wise OR operator
timr_var = '/' ; 10 ms count up variable timr_var = '/' ; 10 ms count up variable
lblary = $0100 ; array with goto labels
vtlstck = $0140 ; gosub stack space, 64 bytes
linbuf = $0200 ; input line buffer linbuf = $0200 ; input line buffer
prgm = $0400 ; VTL02C program grows from here prgm = $0400 ; VTL02C program grows from here
himem = $7900 ; ... up to the top of user RAM himem = $7800 ; ... up to the top of user RAM
vtl02c = $f900 ; interpreter cold entry point vtl02c = $f800 ; interpreter cold entry point
; (warm entry point is startok) ; (warm entry point is startok)
io_area = $bf00 ;configure emulator terminal I/O io_area = $bf00 ;configure emulator terminal I/O
acia_tx = io_area+$f0 ;acia tx data register acia_tx = io_area+$f0 ;acia tx data register
@ -280,11 +302,18 @@ diag = io_area+$fc ;diag reg, bit 7 = exit to mon
sta star ; {*} -> top of user RAM sta star ; {*} -> top of user RAM
lda #hi(himem) lda #hi(himem)
sta star+1 sta star+1
lda #0 ; clear label array & gosub stack
ldx #95
reset1:
sta lblary,x
dex
bpl reset1
sta space ; clear pointer to user stack
startok: startok:
sec ; request "OK" message sec ; request "OK" message
; - - - - - - - - - - - - - - - - - - - - - - - - - - ; ; - - - - - - - - - - - - - - - - - - - - - - - - - - ;
; Start/restart VTL02C command line with program intact ; Start/restart VTL02C command line with program intact
; 32 bytes ;
start: start:
cld ; a sensible precaution cld ; a sensible precaution
ldx #lo(nulstk) ldx #lo(nulstk)
@ -301,11 +330,57 @@ user:
sta lparen sta lparen
sta lparen+1 sta lparen+1
jsr inln ; input a line from the user jsr inln ; input a line from the user
lda linbuf ; check for line label char
cmp #$60
bcc user1
iny ; skip label char
user1:
ldx #pound ; cvbin destination = {#} ldx #pound ; cvbin destination = {#}
jsr cvbin ; skip line number if exists jsr cvbin ; skip line number if exists
jsr d2b ; convert numbers in line to binary jsr d2b ; convert numbers in line to binary
jsr cvbin ; does line start with a number? bne stmnt ; no: execute direct statement
beq direct ; no: execute direct statement lda lblary+62 ; label array populated ?
bne user2 ; yes: skip polpulating it
tya ; no: populate now!
pha
lda #lo(prgm)
sta gthan
lda #hi(prgm)
sta gthan+1
ldaraylp:
ldy #0
lda (gthan),y ; is label ?
cmp #$60
bcc ldaray1 ; no: skip load
and #$1f ; make index to label array
asl a
tax
lda gthan ; line address -> array
sta lblary,x
lda gthan+1
sta lblary+1,x
ldaray1:
ldy #3 ; add offset to next line
lda gthan
ldx gthan+1
clc
adc (gthan),y ; add offset
bcc ldaray2
inx
ldaray2:
sta gthan
stx gthan+1
cpx ampr+1 ; end of program ?
bcc ldaraylp ; no: loop next line
bne ldaray3
cmp ampr
bcc ldaraylp
ldaray3:
sty lblary+62 ; mark populated
pla
tay
user2:
jmp exec
; - - - - - - - - - - - - - - - - - - - - - - - - - - ; ; - - - - - - - - - - - - - - - - - - - - - - - - - - ;
; Delete/insert/replace program line or list program ; Delete/insert/replace program line or list program
; 7 bytes ; 7 bytes
@ -322,6 +397,9 @@ stmnt:
; 20 bytes ; 20 bytes
list_: list_:
jsr findln ; find program line >= {#} jsr findln ; find program line >= {#}
ldx #0
lda (at,x) ; print label
jsr outch
ldx #lparen ; line number for prnum ldx #lparen ; line number for prnum
jsr prnum ; print the line number jsr prnum ; print the line number
lda #' ' ; print a space instead of the lda #' ' ; print a space instead of the
@ -331,98 +409,15 @@ list_:
bcs list_ ; (always taken) bcs list_ ; (always taken)
jskp2: jskp2:
jmp skp2 lda lblary+62 ; label array clear ?
beq skp2 ; then skip clearing it
;-----------------------------------------------------; lda #0 ; clear label array & gosub stack
; The main program execution loop ldx #95
; entry: with (cs) via "beq direct" in user: clr_ls:
; exit: to command line via findln: or "beq start" sta lblary,x
; dex
progr: bpl clr_ls
; beq eloop0 ; if {#} = 0 then ignore and sta space ; clear pointer to user stack
; beq prog_nxt ; no branch - next line
lda arg ; left side of last eval was {#}?
cmp #pound
bne prog_nxt
lda arg+1
beq branch
; ldy lparen+1 ; continue (false branch)
; ldx lparen ; else did {#} change?
; cpy pound+1 ; yes: perform a branch, with
; bne branch ; carry flag conditioned for
; cpx pound ; the appropriate direction.
;; beq eloop ; no: execute next line (cs)
; bne branch
prog_nxt:
ldy #2 ; point {@} to next line address
ldx at+1 ; current line address
lda at
clc
adc (at),y ; {@} low + offset
bcc prg_n1
inx ; {@} high + carry
prg_n1:
cpx ampr+1 ; exceeds end of program?
bcc prg_n2 ; no
bne start ; yes - exit to direct mode
cmp ampr
bcs start
prg_n2: ; (cc)
stx at+1 ; next line address valid!
sta at
ldy #0
lda (at),y
sta lparen ; {(} = {#} = current line number
sta pound
iny
lda (at),y
sta lparen+1
sta pound+1
;prg_same: ; from branch to same line
ldy #3
direct:
php ; (cc: program, cs: direct)
jsr exec ; execute one VTL02C line
plp
bcc progr ; if program mode then continue
lda pound ; if direct mode, did {#} change?
ora pound+1
beq jstart2 ; no: restart "OK" prompt
bne eloop0 ; yes: execute program from {#}
branch:
ldy lparen+1 ; execute a VTL02C branch
ldx lparen
cpy pound+1 ; perform a branch, with
bne branch1 ; carry flag conditioned for
cpx pound ; the appropriate direction.
; beq prg_same ; is the same line again
branch1:
inx ; leave a return address
bne branch2
iny
branch2:
stx bang ; {!} = {(} + 1 (return ptr)
sty bang+1
eloop0:
rol a
eor #1 ; complement carry flag
ror a
eloop:
; jsr findln ; find first/next line >= {#}
jsr find ; inline findln
bcs jstart2 ; if end then restart "OK" prompt
sta pound ; {#} = {(}
stx pound+1 ; end inline
iny ; skip over the length byte
bne direct
jstart2:
jmp start
;-----------------------------------------------------; ;-----------------------------------------------------;
; Delete/insert/replace program line and restart the ; Delete/insert/replace program line and restart the
; command prompt (no "OK" means success) ; command prompt (no "OK" means success)
@ -466,18 +461,24 @@ delt2:
insrt: insrt:
pla pla
tax ; x = linbuf offset pointer tax ; x = linbuf offset pointer
lda linbuf ; push label or blank
cmp #$60
bcs insrt2
lda #' '
insrt2:
pha
lda pound lda pound
pha ; push the new line number on pha ; push the new line number on
lda pound+1 ; the system stack lda pound+1 ; the system stack
pha pha
ldy #2 ldy #3
cntln: cntln:
inx inx
iny ; determine new line length in y iny ; determine new line length in y
lda linbuf-1,x ; and push statement string on lda linbuf-1,x ; and push statement string on
pha ; the system stack pha ; the system stack
bne cntln bne cntln
cpy #4 ; if empty line then skip the cpy #5 ; if empty line then skip the
bcc jstart ; insertion process bcc jstart ; insertion process
tax ; x = 0 tax ; x = 0
tya tya
@ -514,7 +515,7 @@ move2:
dey ; the new line number and store dey ; the new line number and store
sta (at),y ; them in the program gap sta (at),y ; them in the program gap
bne move2 bne move2
ldy #2 ldy #3
txa txa
sta (at),y ; store length after line number sta (at),y ; store length after line number
lda gthan lda gthan
@ -618,8 +619,9 @@ pro_skp: ; inline skpbyte
cmp #' ' cmp #' '
beq pro_skp ; end inline beq pro_skp ; end inline
cmp #';' ; if trailing char is ';' then cmp #';' ; if trailing char is not ';'
beq execrts ; suppress the \n bne outnl ; print \n
rts ; else suppress the \n
outnl: outnl:
lda #$0d ; \n to terminal lda #$0d ; \n to terminal
jmp outch jmp outch
@ -646,9 +648,9 @@ exec:
; beq execrts ; beq execrts
; iny ; iny
lda (at),y ; inline getbyte lda (at),y ; inline getbyte
beq execrts ; do nothing with a null statement beq execend1 ; do nothing with a null statement
cmp #')' ; same for a full-line comment cmp #')' ; same for a full-line comment
beq execrts beq execend1
; sty dolr+1 ; save index if arg[{1}] = arg[{0}] ; sty dolr+1 ; save index if arg[{1}] = arg[{0}]
iny iny
cmp #' ' ; is space? cmp #' ' ; is space?
@ -689,10 +691,44 @@ exec3:
execend: execend:
ldy dolr+1 ; restore line index ldy dolr+1 ; restore line index
pla pla
cmp #stmntdlm ; statement delimiter ? iny
cmp #';' ; statement delimiter ?
beq exec ; continue with next statement beq exec ; continue with next statement
execrts: execend1:
rts ; end of line lda lparen ; direct mode ?
ora lparen+1
beq jstart4
prog_nxt:
ldy #3 ; point {@} to next line address
ldx at+1 ; current line address
lda at
clc
adc (at),y ; {@} low + offset
bcc prg_n1
inx ; {@} high + carry
prg_n1:
cpx ampr+1 ; exceeds end of program?
bcc prg_n2 ; no
bne jstart4 ; yes - exit to direct mode
cmp ampr
bcs jstart4
prg_n2: ; (cc)
stx at+1 ; next line address valid!
sta at
ldy #1
lda (at),y
sta lparen ; {(} = {#} = current line number
sta pound
iny
lda (at),y
sta lparen+1
sta pound+1
ldy #4
jmp exec ; loop next line
jstart4:
sec
jmp start
; special variables including array ; special variables including array
exec_byp: exec_byp:
ldx #arg ; initialize argument pointer ldx #arg ; initialize argument pointer
@ -704,6 +740,7 @@ exec_gb3: ; inline getbyte + skpbyte
iny ; skip space +1 iny ; skip space +1
cmp #' ' ; is space? cmp #' ' ; is space?
beq exec_gb3 beq exec_gb3
; the code below allows (N+1) instead of (N=N+1)
; cmp #'=' ; not '=' implies assigning ; cmp #'=' ; not '=' implies assigning
; beq exec_gb4 ; variable as target & 1st source ; beq exec_gb4 ; variable as target & 1st source
; ldy dolr+1 ; back up to arg[{1}] = arg[{0}] ; ldy dolr+1 ; back up to arg[{1}] = arg[{0}]
@ -717,9 +754,7 @@ exec_gb4:
bne exec_gb4 bne exec_gb4
exec_gb5: ; end inline exec_gb5: ; end inline
cmp #'"' ; yes: print the string with cmp #'"' ; yes: print the string with
bne exec2 beq exec2
jmp prstr ; trailing ';' check & return
exec2:
ldx #arg+2 ; point eval to arg[{1}] ldx #arg+2 ; point eval to arg[{1}]
jsr eval ; evaluate right-side in arg[{1}] jsr eval ; evaluate right-side in arg[{1}]
pha pha
@ -738,29 +773,55 @@ exec2:
cpx #gthan ; if {>=...} statement then call cpx #gthan ; if {>=...} statement then call
beq usr ; user-defined ml routine beq usr ; user-defined ml routine
cpx #pound ; if {#=...} statement then goto cpx #pound ; if {#=...} statement then goto
; beq goto ; arg[{1}] as line number beq goto ; arg[{1}] as line number
bne exec3 cpx #equal ; if {==...} statement then gosub
beq gosub ; arg[{1}] as line number
jmp exec3 ; defaults to store variable
exec2:
jsr prstr ; trailing ';' check & return
jmp execend1
gosub:
lda lparen ; is direct mode ?
ora lparen+1
beq gosub3 ; return to commandline
lda at ; calculate next line address
ldy #3
clc
adc (at),y ; add to offset
tax
lda #0
adc at+1
cmp ampr+1 ; address beyond end of program ?
bcc gosub2
bne gosub3
cpx ampr
bcc gosub2
gosub3:
lda #0 ; then return ends program
tax
gosub2:
ldy space ; load VTL user stack pointer
sta vtlstck,y ; push high
txa
sta vtlstck+1,y ; push low
iny
iny
tya
and #$1f ; wrap around upper linimt
sta space ; save VTL user stack pointer
lda #pound ; point to standard line #
sta arg
ldy #0 ; restore Y
lda arg+2
goto: goto:
tax ; save line # low tax ; save line # low
ora arg+3 ; fall through ? ora arg+3 ; fall through ?
bne goto1 bne goto1
sta arg ; invalidate goto {#} ; sta arg ; invalidate goto {#}
beq execend jmp execend
goto1:
pla ; true goto
cpx lparen ; is same line ?
bne goto2
lda arg+3
cmp lparen+1
bne goto2
ldy #3 ; start over
jmp exec
goto2:
tya ; different line
pha ; invalidate {;}
txa ; restore line # low
jmp exec3 ; store new line in {#}
usr: usr:
tax ; jump to user ml routine with tax ; jump to user ml routine with
lda arg+3 ; arg[{1}] in a:x (MSB:LSB) lda arg+3 ; arg[{1}] in a:x (MSB:LSB)
@ -774,33 +835,118 @@ poke:
joutch: joutch:
jsr outch ; print character jsr outch ; print character
jmp execend jmp execend
;-----------------------------------------------------;
; {?=...} handler; called by exec:
; 2 bytes
prnum0: prnum0:
ldx #arg+2 ; x -> arg[{1}], fall through ldx #arg+2 ; x -> arg[{1}], fall through
jsr prnum jsr prnum
jmp execend jmp execend
goto1:
lda lparen ; set {!} as return line #
sta bang
lda lparen+1
sta bang+1
inc bang ; + 1
bne goto11
inc bang+1
goto11:
pla ; true goto
ldy arg+3 ; is physical address pointer ?
cpy #$ff
beq goto3
ora lparen ; direct mode ?
beq goto12
cpy lparen+1 ; set carry flag for find
bne goto2
cpx lparen
bne goto2
ldy #4 ; same line - start over
jmp exec
goto5:
txa ; build address to label array
and #$1f
asl a
tay
lda lblary,y ; load address from array
sta at
iny
lda lblary,y ; load address from array
sta at+1
bne goto7 ; if initialized
jstart3:
sec ; print OK
jmp start
goto12:
clc ; from start of prog
goto2:
; tya ; different line
; pha ; invalidate {;}
; txa ; restore line # low
; jmp exec3 ; store new line in {#}
stx pound ; store target
sty pound+1
jsr find
bcs jstart3 ; end of program
sta pound
stx pound+1
iny ; y = 3
jmp exec
goto3:
cpx #'=' ; from stack ?
bne goto5 ; else is label
ldy space ; load stack pointer
bne goto4
ldy #$20 ; wrap around
goto4:
dey ; load new address from stack
lda vtlstck,y
sta at
dey
lda vtlstck,y
beq jstart3 ; if not initialized
sta at+1
sty space ; save stack pointer
goto7:
ldy #1 ; load line #
lda (at),y
sta lparen
sta pound
iny
lda (at),y
sta lparen+1
sta pound+1
ldy #4
jmp exec
; - - - - - - - - - - - - - - - - - - - - - - - - - - ; ; - - - - - - - - - - - - - - - - - - - - - - - - - - ;
; Print an unsigned decimal number (0..65535) in var[x] ; Print an unsigned decimal number (0..65535) in var[x]
; entry: var[x] = number to print ; entry: var[x] = number to print
; uses: div:, outch:, var[x+2], saves original {%} ; uses: outch:, gthan
; exit: var[x] = 0, var[x+2] = 10 ; exit: var[x] = 0
; 43 bytes ;
prnum: prnum:
lda remn
pha ; save {%}
lda remn+1
pha
lda #0 ; null delimiter for print lda #0 ; null delimiter for print
pha pha
sta 3,x prnum2: ; divide var[x] by 10
lda #10 ; divisor = 10 lda #0
sta 2,x ; repeat { sta gthan+1 ; clr BCD
prnum2: lda #16
jsr div ; divide var[x] by 10 sta gthan ; {>} = loop counter
lda remn prdiv1:
ora #'0' ; convert remainder to ASCII asl 0,x ; var[x] is gradually replaced
rol 1,x ; with the quotient
rol gthan+1 ; BCD result is gradually replaced
lda gthan+1 ; with the remainder
sec
sbc #10 ; partial BCD >= 10 ?
bcc prdiv2
sta gthan+1 ; yes: update the partial result
inc 0,x ; set low bit in partial quotient
prdiv2:
dec gthan
bne prdiv1 ; loop 16 times
lda gthan+1
ora #'0' ; convert BCD result to ASCII
pha ; stack digits in ascending pha ; stack digits in ascending
lda 0,x ; order ('0' for zero) lda 0,x ; order ('0' for zero)
ora 1,x ora 1,x
@ -810,10 +956,6 @@ prnum3:
jsr outch ; print digits in descending jsr outch ; print digits in descending
pla ; order until delimiter is pla ; order until delimiter is
bne prnum3 ; encountered bne prnum3 ; encountered
pla
sta remn+1 ; restore {%}
pla
sta remn
rts rts
;-----------------------------------------------------; ;-----------------------------------------------------;
; Evaluate a (hopefully) valid VTL02C expression at ; Evaluate a (hopefully) valid VTL02C expression at
@ -853,9 +995,9 @@ notdn:
eval_gb: ; inline getbyte eval_gb: ; inline getbyte
lda (at),y lda (at),y
beq evalrts beq evalrts
iny ; skip over any space char(s) cmp #';' ; statement delimiter ?
cmp #stmntdlm ; statement delimiter ?
beq evalrts beq evalrts
iny ; skip over any space char(s)
cmp #' ' ; is space? cmp #' ' ; is space?
beq eval_gb ; end inline beq eval_gb ; end inline
@ -874,8 +1016,11 @@ getval:
; sta 1,x ; sta 1,x
lda (at),y ; get variable or constant lda (at),y ; get variable or constant
bpl getvar bpl getvar
beq getrts ; safety exit - end of banana ; cmp ';'
; beq getrts
iny iny
; cmp #' ' ; skip space
; beq getval
; get constant ; get constant
cmp #$fd ; constant type ? cmp #$fd ; constant type ?
bcs getword bcs getword
@ -907,6 +1052,9 @@ clrhigh:
rts rts
; get variable ; get variable
getvar: getvar:
beq getrts ; safety exit - end of banana
cmp ';'
beq getrts
iny iny
cmp #'@' ; peek? cmp #'@' ; peek?
bcs getv_byp ; bypass variables >= @ bcs getv_byp ; bypass variables >= @
@ -916,12 +1064,20 @@ getvar:
beq getary beq getary
cmp #'(' ; sub-expression? cmp #'(' ; sub-expression?
beq eval ; yes: evaluate it recursively beq eval ; yes: evaluate it recursively
cmp #'=' ; return after gosub
beq gotomark
cmp #'$' ; user char input? cmp #'$' ; user char input?
beq in_chr beq in_chr
cmp #'?' ; user line input? cmp #'?' ; user line input?
beq in_val beq in_val
getv_byp: getv_byp:
beq peek beq peek
cmp #$60 ; line # variable
bcs gotomark
; first set var[x] to the named variable's address,
; then replace that address with the variable's actual
; value before returning
sty dolr ; get simple variable sty dolr ; get simple variable
asl a asl a
@ -936,9 +1092,6 @@ getv_byp:
ldy dolr ldy dolr
rts rts
; first set var[x] to the named variable's address,
; then replace that address with the variable's actual
; value before returning
getary: ; get array variable getary: ; get array variable
jsr convp_array jsr convp_array
lda (0,x) lda (0,x)
@ -965,6 +1118,12 @@ peek: ; memory access?
sta 1,x sta 1,x
rts rts
gotomark: ; special line # 65280 +
sta 0,x ; low = stack/label
lda #$ff
sta 1,x ; 65280
rts
in_chr: ; user char input? in_chr: ; user char input?
jsr inch ; input one char jsr inch ; input one char
sta 0,x sta 0,x
@ -980,8 +1139,15 @@ in_val: ; user line input
lda at+1 lda at+1
pha pha
jsr inln ; input expression from user jsr inln ; input expression from user
lda linbuf ; empty ?
bne in_val2
sta 0,x ; defaults to 0
sta 1,x
beq in_val3
in_val2:
jsr d2b ; convert numbers in line to binary jsr d2b ; convert numbers in line to binary
jsr eval ; evaluate, var[x] = result jsr eval ; evaluate, var[x] = result
in_val3:
pla pla
sta at+1 sta at+1
pla pla
@ -1308,49 +1474,55 @@ cvbin3:
;-----------------------------------------------------; ;-----------------------------------------------------;
; Accept input line from user and store it in linbuf, ; Accept input line from user and store it in linbuf,
; zero-terminated (allows very primitive edit/cancel) ; zero-terminated (allows very primitive edit/cancel)
; entry: (jsr to inln or newln, not inln6) ; entry: (jsr to inln or newln)
; used by: user:, getval: ; used by: user:, getval:
; uses: inch:, outnl:, linbuf, {@} ; uses: inch:, outnl:, linbuf, {@}
; exit: @[y] -> linbuf ; exit: @[y] -> linbuf
; 42 bytes ;
inln6: ;newln:
cmp #ESC ; escape?
beq newln ; yes: discard entire line
iny ; line limit exceeded?
bpl inln2 ; no: keep going
newln:
; jsr outnl ; yes: discard entire line ; jsr outnl ; yes: discard entire line
ldy #0
inln4:
jsr outcr
lda erase_line,y
beq inln
jsr outch
iny
bpl inln4
inln: inln:
ldy #lo(linbuf); entry point: start a fresh line ldy #lo(linbuf); entry point: start a fresh line
sty at ; {@} -> input line buffer sty at ; {@} -> input line buffer
ldy #hi(linbuf) ldy #hi(linbuf)
sty at+1 sty at+1
ldy #1 ldy #0
inln5: inlnlp: ; main loop
dey
bmi newln
inln2:
jsr inch ; get (and echo) one key press jsr inch ; get (and echo) one key press
cmp #BS ; backspace? cmp #BS ; backspace?
beq inln5 ; yes: delete previous char beq inlnbs ; yes: delete previous char
cmp #ESC ; escape?
beq inlnesc ; yes: discard entire line
cmp #$0d ; cr? cmp #$0d ; cr?
bne inln3 beq inlncr
lda #0 ; yes: replace with null cmp #' ' ; do not store ctrl keys
inln3: bcc inlnlp
sta (at),y ; put key in linbuf sta (at),y ; put key in linbuf
bne inln6 ; continue if not null iny
bpl inlnlp ; loop if < len(linbuf)
lda #BS ; hold at end of buffer
jsr outch
inlnbs:
dey ; backspace
bpl inlnlp
lda #13 ; hold at begin of buffer
jsr outch
iny
bpl inlnlp
inlncr:
lda #0 ; cr - mark end of line
sta (at),y
tay ; y = 0 tay ; y = 0
rts rts
erase_line: inlnesc:
db ESC,"[K",0 cpy #0 ; escape - reverse all input
beq inlnlp
lda #BS
inlnesc1:
jsr outch
dey
bne inlnesc1
beq inlnlp
;-----------------------------------------------------; ;-----------------------------------------------------;
; Find the first/next stored program line >= {#} ; Find the first/next stored program line >= {#}
; entry: (cc): start search at program beginning ; entry: (cc): start search at program beginning
@ -1358,8 +1530,8 @@ erase_line:
; ({@} -> beginning of current line) ; ({@} -> beginning of current line)
; used by: skp2:, findln: ; used by: skp2:, findln:
; uses: prgm, {@ # & (} ; uses: prgm, {@ # & (}
; exit: (cs): {@}, x:a and {(} undefined, y = 2 ; exit: (cs): {@}, x:a and {(} undefined, y = 3
; (cc): {@} -> beginning of found line, y = 2, ; (cc): {@} -> beginning of found line, y = 3,
; x:a = {(} = actual found line number ; x:a = {(} = actual found line number
; 62 bytes ; 62 bytes
find: find:
@ -1367,7 +1539,7 @@ find:
lda #lo(prgm) lda #lo(prgm)
bcc find1st ; cc: search begins at first line bcc find1st ; cc: search begins at first line
ldx at+1 ldx at+1
ldy #2 ldy #3
findnxt: findnxt:
lda at lda at
cmp ampr cmp ampr
@ -1383,7 +1555,7 @@ find1st:
stx at+1 stx at+1
find5: find5:
sta at sta at
ldy #0 ldy #1
lda (at),y lda (at),y
sta lparen ; {(} = current line number sta lparen ; {(} = current line number
cmp pound ; (invalid if {@} >= {&}, but cmp pound ; (invalid if {@} >= {&}, but
@ -1410,22 +1582,24 @@ findrts:
; if high byte is $00 then 2 bytes $FD $01-$FF ; if high byte is $00 then 2 bytes $FD $01-$FF
; ;
d2b: d2b:
php
txa ; save pointer to arg txa ; save pointer to arg
pha pha
tya
pha
lda #0 ; statement position counter lda #0 ; statement position counter
sta dolr+1 sta dolr+1
d2blp: ; main loop d2blp: ; main loop
inc dolr+1 ; next var, operator or constant inc dolr+1 ; next var, operator or constant
ldx #space ; cvbin converts to space var ldx #equal ; cvbin converts to equal var
jsr cvbin ; convert if decimal jsr cvbin ; convert if decimal
beq d2b1 ; if not a constant beq d2b1 ; if not a constant
d2b6: d2b6:
; sty ques+1 ; save to continue later
ldx ques ; x = y before conversion ldx ques ; x = y before conversion
inc ques ; always uses at least 1 byte inc ques ; always uses at least 1 byte
lda space+1 ; is < 125 ? lda equal+1 ; is < 125 ?
bne d2b2 bne d2b2
lda space lda equal
cmp #125 cmp #125
bcs d2b2 bcs d2b2
ora #$80 ; < 125 = 1 byte ora #$80 ; < 125 = 1 byte
@ -1435,15 +1609,15 @@ d2b2: ; >= 125 = 2 or 3 bytes
inc ques ; uses at least 2 bytes inc ques ; uses at least 2 bytes
lda #$ff ; mark word constant lda #$ff ; mark word constant
sta ques+1 sta ques+1
lda space ; constant low lda equal ; constant low
bne d2b8 bne d2b8
dec ques+1 ; clear bit 0 in marker = $FE dec ques+1 ; clear bit 0 in marker = $FE
lda space+1 ; store only constant high lda equal+1 ; store only constant high
sta linbuf+1,x sta linbuf+1,x
bne d2b19 bne d2b19
d2b8: d2b8:
sta linbuf+1,x ; store constant low sta linbuf+1,x ; store constant low
lda space+1 ; constant high lda equal+1 ; constant high
bne d2b9 bne d2b9
dec ques+1 ; clear bit 1 in marker = $FD dec ques+1 ; clear bit 1 in marker = $FD
dec ques+1 dec ques+1
@ -1470,40 +1644,36 @@ d2b7:
d2b1: d2b1:
lda linbuf,y ; is end of line ? lda linbuf,y ; is end of line ?
beq d2bex ; exit beq d2bex ; exit
; jsr outch ; debug
iny iny
; pha cmp #';' ; new statement starts
cmp #stmntdlm ; new statement starts
bne d2b10 bne d2b10
; lda dolr+1 ; in operator position (even)
; and #1
; bne d2b10
lda #0 lda #0
sta dolr+1 ; clear position pointer sta dolr+1 ; clear position pointer
; pla
beq d2blp ; loop next beq d2blp ; loop next
d2b10: d2b10:
; pla cmp #$60 ; prevent lower case on left side
; cmp #'(' ; neither var nor op bcc d2b11
; beq d2b11 ldx dolr+1 ; is target variable ?
; cmp #')' ; neither var nor op cpx #1
; bne d2b12 bne d2blp
;d2b11: and #$5f ; convert to upper case
; inc dolr+1 ; stays odd (var) or even (op) sta linbuf-1,y
;d2blp1 bne jd2blp
; jmp d2blp d2b11:
d2b12:
cmp #'"' ; potential string ? cmp #'"' ; potential string ?
bne d2blp bne jd2blp
lda dolr+1 ; exit on 3rd position (is string) lda dolr+1 ; exit on 3rd position (is string)
cmp #3 cmp #3
bne d2blp ; loop if not bne jd2blp ; loop if not
d2bex: d2bex:
; jsr outnl ;debug
pla ; restore pointer to arg pla ; restore pointer to arg
tay
pla
tax tax
ldy #0 plp
rts rts
jd2blp:
jmp d2blp
;-----------------------------------------------------; ;-----------------------------------------------------;
; Fetch a byte at @[y], ignoring space characters ; Fetch a byte at @[y], ignoring space characters
; 10 bytes ; 10 bytes
@ -1599,16 +1769,22 @@ skip_esc_discard:
cpy #1 cpy #1
bne inch ; discard escape sequence bne inch ; discard escape sequence
lda #27 ; escape only - send to vtl lda #27 ; escape only - send to vtl
rts ; ldy dolr
; rts
skip_esc_no skip_esc_no
ldy dolr ; restore y reg ldy dolr ; restore y reg
inch2: inch2:
and #$7f ; ensure char is positive ascii and #$7f ; ensure char is positive ascii
; cmp #$03 ; ctrl-C? ; cmp #$03 ; ctrl-C?
jsr test_abort jsr test_abort
jmp outch ; no: echo to terminal cmp #BS ; only echo printable, bs & cr
istart: beq outch
jmp start ; yes: abort to "OK" prompt cmp #13
beq outch
cmp #' '
bcs outch
sec
rts
test_abort: test_abort:
cmp #3 ; is ctrl-c cmp #3 ; is ctrl-c
@ -1617,10 +1793,13 @@ test_abort:
beq abort ; yes: exit to monitor beq abort ; yes: exit to monitor
rts rts
abort: abort:
jsr outcr
lda #$80 ; exit to monitor lda #$80 ; exit to monitor
sta diag sta diag
lda #ESC ; escape after continue lda #ESC ; escape after continue
rts rts
istart:
jmp start ; yes: abort to "OK" prompt
; - - - - - - - - - - - - - - - - - - - - - - - - - - ; ; - - - - - - - - - - - - - - - - - - - - - - - - - - ;
; Print ascii char in a to stdout, (cs) ; Print ascii char in a to stdout, (cs)
; ;
@ -1647,20 +1826,20 @@ skip_bs:
; ;
IRQ_10ms: IRQ_10ms:
pha pha
inc timr_adr ; increment the variable {/} inc timr_adr ; increment the variable {/}
bne IRQ_exit bne IRQ_exit
inc timr_adr+1 inc timr_adr+1
IRQ_exit: IRQ_exit:
lda #1 ; clear interrupt flag lda #1 ; clear interrupt flag
sta timr_fl sta timr_fl
pla pla
rti rti
; Start the timer prior to VTL ; Start the timer prior to VTL
IRQ_start: IRQ_start:
lda #1 ; set bit 0 (10ms tick) lda #1 ; set bit 0 (10ms tick)
sta timr_ie ; -> interrupt enable sta timr_ie ; -> interrupt enable
cli cli
jmp vtl02c ; continue cold start jmp vtl02c ; continue cold start
;-----------------------------------------------------; ;-----------------------------------------------------;
org $fffc org $fffc
dw IRQ_start ; reset vector -> cold start dw IRQ_start ; reset vector -> cold start