[A83] Re: BASIC interpreter
[Prev][Next][Index][Thread]
[A83] Re: BASIC interpreter
Thanks a lot!!!
Thomas Lutz
Stevens Institute of Technology
-----Original Message-----
From: assembly-83-bounce@lists.ticalc.org
[mailto:assembly-83-bounce@lists.ticalc.org] On Behalf Of Henk Poley
Sent: Monday, December 17, 2001 2:09 PM
To: assembly-83@lists.ticalc.org
Subject: [A83] Re: BASIC interpreter
> Van: Thomas Lutz <tlutz@stevens-tech.edu>
>=20
> Is there a way to find out the location of the BASIC interpreter??
(i.e.
> when you run an asm program from within a basic program, can you tell
> where the interpreter is??
> )
> thanks!
I guess you meant to say "where the BASIC interpreter left off". That
can
be found at:
[Ti83:]
Byte 913B Type of running BASIC program
8 913C Name of currently running BASIC program
Word 9144 Pointer to start of running BASIC program
Word 9146 Pointer to currently interpreted byte in running BASIC prog
Word 9148 Pointer to last byte of data in running BASIC program
[Ti83+:]
Byte 9652 - Type of running BASIC program
8 9653 - Name of running BASIC program
Word 965B - Pointer to start of running BASIC
program
Word 965D - Pointer to current position in BASIC
prog
Word 965F - Pointer to last byte of BASIC program
I've also got the Ti82 adress but these aren't very usefull since the
BASIC
interpreter isn't 'running' when you enter an assembly prog on the Ti82.
An example of how to load the pointer from the previous running BASIC
program:
call _cpyTo1FPST ; last FPS entry -> OP1[0,8]
call _findProgSym ; Get program location
push de ; DE =3D sizebytes pointer
inc de ;
inc de ;
ld (pBASIC_start),de ;
push de ;
dec de ;
dec de ;
call _getVarSize ; DE =3D sizebytes + 2, HL =3D intact
add hl,de ;
ld (pBASIC_end),hl ; Store end of BASIC prog
pop de ; DE =3D sizebytes pointer
inc de ;
inc de ; DE =3D data pointer
ld hl,(OPS) ; Get operator stack pointer
ld bc,6 ; Add 6 to get cursor offset
add hl,bc ;
call LD_HL_MHL ; Get cursor offset
add hl,de ; Add cursor offset to program location
ld (pBASIC_cursor),hl ;
ret ;
An example program (Ti83), it deletes a program, the small starter is
created by Jean Carot (aka Yhean).
Syntax: send(9prgmDELP:(prgmXXX)
There are probably some opts to be done, but most of the code isn't
needed
anymore when you port it to Venus.
;=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D
; '1'-'9'
;30 e JR NC,(PC+e) ;
;31 n n LD SP,nn ; AH!!!
;32 n n LD (nn),A ;
;33 INC SP ; AH!
;34 INC (HL) ;
;35 DEC (HL) ;
;36 n LD (HL),n ;
;37 SCF ;
;38 e JR C,(PC+e) ;
;39 ADD HL,SP ;
; 'A'-'F'
;41 LD B,C ;
;42 LD B,D ;
;43 LD B,E ;
;44 LD B,H ;
;45 LD B,L ;
;46 LD B,(HL) ;
;=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D
_errundefined =3D $467B ; ERR:UNDEFINED <<
_errargument =3D $4672 ; ERR:ARGUMENT <<
_errsyntax =3D $466C ; ERR:SYNTAX <<
;=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D
_getProgInfo =3D $4426
_chkfindsym =3D $442A
_findsym =3D $442E
_delVar =3D $44AA
_deleteMem =3D $44B2
;=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D
OP1 =3D $8039
userMemOffset =3D $8565
CMDShadow =3D $9157
;=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D
STRINGOBJ =3D $04
PROGOBJ =3D $05
;=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D
#define RelocBuf CMDShadow
;=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D
startup:
.db "CD2644D5C9" ; call _findprogsym / push de / ret
startupSize =3D ($ - startup) / 2
.db "=D4?0000?" ; End / :0000 / :[asm prog]
;=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D
;Together this (=3D non-safeStartup) translates to:
;------------------------------------------------
;xxxx xxxx ; ..sizebytes.. (should be a
do-nothing-OPcode)
;43 LD B,E ; nonsense load
;44 LD B,H ; nonsense load
;323634 LD ($3436),A ; nonsense, write to ROM...
;34 INC (HL) ; nonsense increment
;44 LD B,H ; nonsense load
;35 DEC (HL) ; nonsense decrement
;43 LD B,E ; B =3D E (also nonsense)
;39 ADD HL,SP ; HL =3D HL + SP [-400,0] (carry is now
set)
;=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3Dend of =
starter=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
;D43F30 CALL NC,($303F) ; do nothing
;3030 JR NC,($+$30+2) ; do nothing
;3037 JR NC,($+$37+2) ; do nothing
;=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D
; HL =3D points right here
ld de,DelStart-$ ;
add hl,de ;
ld bc,DelEnd-DelStart ; <=3D 128 !!!
ld de,RelocBuf ;
push de ;
ldir ;
ret ; 'Jump' to CMDShadow
;=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D
DelStart:
ld bc,$0000 ; Hmm, else BC isn't zero...
ld (userMemOffset),bc ;
ld hl,$9327 ;
ld de,startupSize ;
call _deleteMem ; Remove startup
.ds startupSize ; NOPs
;=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D
; Now precalc some data
;=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D
ld hl,($9148) ; HL =3D BASIC_End
ld de,($9146) ; DE =3D BASIC_cursor
or a ;
sbc hl,de ;
ex de,hl ; DE =3D bytes till end of BASIC prog
; HL =3D BASIC_cursor
=20
ld bc,8+1 ; Maximum 8 bytes in name
sizeLoop:
ld h,d ;
ld l,e ;
dec bc ;
or a ;
sbc hl,bc ;
jr c,sizeLoop ;
; BC =3D max namestring size
ld hl,($9146) ; Recall BASIC_cursor
inc hl ;
ld a,$3E ; ':'
cp (hl) ;
jp nz,_errsyntax ;
inc hl ;
ld a,$10 ; '('
cp (hl) ;
jp nz,_errsyntax ;
inc hl ;
ld ($9146),hl ; Store new BASIC_cursor
ld a,$5F ; 'prgm'
cp (hl) ;
jp nz,_errargument ;
inc hl ;
=20
ld ($9146),hl ; Store new BASIC_cursor
ld de,OP1 ;
ld a,PROGOBJ ;
=20
nameLoop:
ld (de),a ;
ld a,(hl) ;
inc de ;
inc hl ;
cp '?' ; tEnter
jr z,endNameLoop ;
cp $11 ; ')'
jr z,endNameLoop ;
djnz nameLoop ;
endNameLoop:
xor a ;
ld (de),a ; Add zero-terminator
=20
push hl ;
call _getProgInfo ;
ld (VATpointer),hl ;
pop hl ;
jp c,_errundefined ;
ld ($9146),hl ; Store new BASIC_cursor
ld hl,(VATpointer) ;
jp _delVar ;
=20
DelEnd:
.db "=D4HPOLEY=D4"
References: