Invoking the Basic interpreter from a ML program

This could be useful

	
FastCircle:

; credits to  Sean McLaughlin (<a href="mailto:sigma_zk@yahoo.com">sigma_zk@yahoo.com</a>) for his TI-83 code  -01/18/04 (mm/dd/yy)
; Note: this version clips the circle withing the 256x192 screen
;
;D = center_x
;E = center_y
;C = radius

	LD	A,C				;
	OR	A				;
	RET	Z				;
	RET	M				;
	
	LD	(_x),DE			;
	LD	B,0				; B = y
	LD	H,B				;
	LD	L,C				; 
	ADD	HL,HL			;
	LD	DE,3			;
	EX	DE,HL			;
	SBC	HL,DE			; HL = err = 3-radius*2

_loop:					;
	LD	DE,(_x)			; DE = (xc,yc)
	LD	A,C				; A = x
	CP	B				; nc if (x <= y)
	RET	C				;
;PSet(xc + x, yc + y)	;
	LD	A,E				; A = yc
	ADD	A,B				; A = yc + y
	LD	E,A				; E = yc + y
	EX	AF,AF'			;
	LD	A,D				; A = xc
	ADD	A,C				; A = xc + x
	LD	D,A				; DE = (xc+x,yc+y)
	push af				; save the C flag for X clipping
	CALL	nc,PSet		;
	
;PSet(xc + x, yc - y)	;
	LD	A,E				; A = yc + y
	SUB	B				; A = yc
	SUB	B				; A = yc - y
	LD	E,A				; DE = (xc+x,yc-y)
	pop	af				; restore the C flag for X clipping
	CALL	nc,PSet		;
	
;PSet(xc - x, yc - y)	;
	LD	A,D				; A = xc + x
	SUB	C				; A = xc
	SUB	C				; A = xc - x
	LD	D,A				; DE = (xc-x,yc-y)
	push af				; save the C flag for X clipping
	CALL	nc,PSet		;
;PSet(xc - x, yc + y)	;
	EX	AF,AF'			;
	LD	E,A				; DE = (xc-x,yc+y)
	pop	af				; restore the C flag for X clipping
	CALL	nc,PSet		;
;PSet(xc + y, yc + x)	;
	LD	A,E				; A = yc + y
	SUB	B				; A = yc
	ADD	A,C				; A = yc + x
	LD	E,A				; E = yc + x
	LD	A,D				; A = xc - x
	ADD	A,C				; A = xc
	ADD	A,B				; A = xc + y
	LD	D,A				; DE = (xc+y,yc+x)
	PUSH	AF			; save[XC+Y] and C flag for X clipping
	CALL	nc,PSet		;
;PSet(xc - y, yc + x)	;
	LD	A,D				; A = xc + y
	SUB	B				; A = xc
	SUB	B				; A = xc - y
	LD	D,A				; DE = (xc-y,yc+x)
	push	af			; save the C flag for X clipping
	CALL	nc,PSet		;
;PSet(xc - y, yc - x)	;
	LD	A,E				; A = yc + x
	SUB	C				; A = yc
	SUB	C				; A = yc - x
	LD	E,A				; DE = (xc-y,yc-x)
	pop	af				; restore the C flag for X clipping
	CALL	nc,PSet		;
;PSet(xc + y, yc - x)	;
	POP	AF				; A = xc + y		and C flag for X clipping
	LD	D,A				; DE = (xc+y,yc-x)
	CALL	nc,PSet		;

;if(d < 0) err += y << 2 + 6
	BIT	7,H				;
	JR	Z,_PosError
	EX	DE,HL			;
	LD	H,0				;
	LD	L,B				;
	ADD	HL,HL			;
	ADD	HL,HL
	ADD	HL,DE
	LD	DE,6
	ADD	HL,DE
	INC	B
	JP	_loop

_PosError:
;err += (y - x) << 2 + 10: y--
	LD	DE,10
	ADD	HL,DE
	DEC	D
	LD	A,B
	SUB	C
	ADD	A,A
	RL	D
	ADD	A,A
	RL	D
	LD	E,A
	ADD	HL,DE
	INC	B
	DEC	C
	JP	_loop

					
	global _tmp

PSet:
	ld	a,0C0h-1
	cp	e
	ret c					
	
	push de    ; D = x, E = y
	exx
	pop	bc
	
	;Y -> C
	;X -> B

	
	ld	hl,_tmp
	LD (HL),C
	LD A,B
	AND 7
	LD C,A
	XOR B
	XOR 6
	RRD
	di
	OUT (99h),A
	LD E,A
	LD A,(HL)
	RLCA
	LD D,A
	and	7fh
	OUT (99h),A
	LD H,0D8h
	LD A,(DE)
	LD L,C
	XOR (HL)
	LD (DE),A
	OUT (98h),A
	ei
	exx
	ret

psect	bss,class=DATA
	
_x:	defs	1
	defs	1

Note that _tmp is a byte in ram and _x is a word in ram

There is also the following way.

ld hl,_basstr
call 42B2H  ;CRUNCH
ld hl,F41FH
call 4601H ;NEWSTT
ret
_basstr: defm ":CIRCLE(10,10),10,10:PAINT(10,10),10,10"
defb 0

The method to call NEWSTT(4601H) can use the BASIC variables
When NEWSTT is called, the program returns to BASIC prompt.
The following program will work well.

ld hl,_basstr1
call _execbas
ld hl,_basstr2
call _execbas
ld hl,_basstr3
call _execbas
ret

_execbas:
call 42B2H  ;CRUNCH
pop hl
ld a,0c3h
ld (0f55eh),a
ld (0f55fh),hl
ld hl,0f41fh
jp 4601h ;NEWSTT

_basstr1: defm ":DEFUSR1=&HF55E:X=USR1(0)"
defb 0
_basstr2: defm ":A=10:B=10:X=USR1(0)"
defb 0
_basstr3: defm ":PRINT A+B:X=USR1(0)"
defb 0

Hmm... Instead of #F55E I would propably try HPRGE (#FEF8) or HREAD (#FF07) instead in order to get rid of that DEFUSR / USR stuff... Naturally this means that in this case you have to manually clear the hooks if you plan to exit the program.