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Using the floating point routines in the BASIC ROM.

The “stdlib.a” which is required by this asm source can be found in the Resurrection project ZIP file.

;Mandelbrot test code

!source "../stdlib/stdlib.a"
!to "Mandelbrot.prg", cbm
!sal
!sl "Mandelbrot.map"
!svl "Mandelbrot.lbl"
!cpu 6510
!ct pet

!source "../stdlib/BASICEntry80d.a"

!macro OutputFAC {
	jsr $bddd	; Convert FAC#1 to ASCII String. Kills FAC#2
	jsr $b487	; Set Up String
	jsr $ab21	; Output String
}

LDFAC = $bba2
STFAC = $bbd4
SUBFAC = $b850
DIVFAC = $bb0f
CMPFAC = $bc5b
MULFAC = $ba28
ADDFAC = $b867
SETFAC = $b391

!macro LoadFAC .addr {
	lda #<.addr
	ldy #>.addr
	jsr LDFAC
}

!macro StoreFAC .addr {
	ldx #<.addr
	ldy #>.addr
	jsr STFAC
}

!macro SubMemFAC .addr {
	lda #<.addr
	ldy #>.addr
	jsr SUBFAC
}
!macro SubFACMem .addr {
	+StoreFAC Temp
	+LoadFAC .addr
	+SubMemFAC Temp
}

!macro DivMemFAC .addr {
	lda #<.addr
	ldy #>.addr
	jsr DIVFAC
}
!macro DivFACMem .addr {
	+StoreFAC Temp
	+LoadFAC .addr
	+DivMemFAC Temp
}

!macro CmpFACMem .addr {
	+StoreFAC Temp
	+LoadFAC .addr
	+CmpMemFAC Temp
}
!macro CmpMemFAC .addr {
	lda #<.addr
	ldy #>.addr
	jsr CMPFAC
}

!macro MulMemFAC .addr {
	lda #<.addr
	ldy #>.addr
	jsr MULFAC
}

!macro AddMemFAC .addr {
	lda #<.addr
	ldy #>.addr
	jsr ADDFAC
}

!macro SetFAC_Y {
	lda #0
	jsr SETFAC
}

kMaxIterations = 26

!zn
*=BASICEntry
	cld
	jsr CINT

;xs=(xmax-xmin)/40.0;
	+LoadFAC xmin
	+SubMemFAC xmax
	+DivFACMem ScrW
	+StoreFAC xs

;ys=(ymax-ymin)/24.0;
	+LoadFAC ymin
	+SubMemFAC ymax
	+DivFACMem ScrH
	+StoreFAC ys

;for (y=0;y<24;y++) {
	lda #0
	sta y

.l1
;   for (x=0;x<40;x++) {
	lda #0
	sta x

.l2
;      p=xmin+(x*xs);
	ldy x
	+SetFAC_Y
	+MulMemFAC xs
	+AddMemFAC xmin
	+StoreFAC p
	

;      q=ymin+(y*ys);
	ldy y
	+SetFAC_Y
	+MulMemFAC ys
	+AddMemFAC ymin
	+StoreFAC q


;         xtemp=0;
;         x0=0;
;         y0=0;
	ldy #0
	+SetFAC_Y
	+StoreFAC x0
	+StoreFAC y0


;         i=0;
	lda #0
	sta i

.while
;         while (((x0*x0)+(y0*y0))<4 && ++i<kMaxIterations)  {
	; i check, first, simple integer check
	lda i
	cmp #kMaxIterations
	bcc .ltkMaxIterations

	jmp .escape
.ltkMaxIterations

	; mul check
	+LoadFAC x0
	+MulMemFAC x0
	+StoreFAC Temp2
	+LoadFAC y0
	+MulMemFAC y0
	+AddMemFAC Temp2
	+CmpFACMem Escape
	bcc .lt4
	jmp .escape
.lt4

	;++i
	inc i

;			xtemp = (x0*x0) - (y0*y0) + p
	+LoadFAC x0
	+MulMemFAC x0
	+StoreFAC Temp2
	+LoadFAC y0
	+MulMemFAC y0
	+SubMemFAC Temp2
	+AddMemFAC p
	+StoreFAC xtemp

;            y0=(2 * x0 * y0) +q;
	+LoadFAC x0
	+MulMemFAC y0
	+StoreFAC Temp2
	ldy #2
	+SetFAC_Y
	+MulMemFAC Temp2
	+AddMemFAC q
	+StoreFAC y0


;            x0=xtemp;
	+LoadFAC xtemp
	+StoreFAC x0

;            }
	jmp .while

.escape
	; Range check to adjust for printable characters
	lda i
;	lsr			; Potential for shit adjustment, change kMaxIterations to accomodate
	cmp #26		; Letters in the alphabet!
	bcc .okChar
	lda #' '
	jmp .rawOut
.okChar
	clc
	adc #64
.rawOut
	jsr CHROUT

	; Finish for loops
	inc x
	lda x
	cmp #40
	beq .ol2
	jmp .l2
.ol2
	inc y
	lda y
	cmp #24		; MPi: TOOD: Keep the last line clear for an IRQ scrolling message
	beq .ol1
	jmp .l1
.ol1

.flash
;	inc VIC2BorderColour
	jmp .flash

; C64 Floating point values
; MPi: TODO: Must update the assembler to create these
xmin	!by $82, $a0, $00, $00, $00		; -2.5
xmax	!by $81, $40, $00, $00, $00		; 1.5
ymin	!by $81, $c0, $00, $00, $00		; -1.5
ymax	!by $81, $40, $00, $00, $00		; 1.5
ScrW	!by $86, $20, $00, $00, $00		; 40
ScrH	!by $85, $40, $00, $00, $00		; 24
Escape	!by $83, $00, $00, $00, $00		; 4

; Float storage
Temp	= *
Temp2	= * + 5
xs		= * + 10
ys		= * + 15
p		= * + 20
q		= * + 25
xtemp	= * + 30
x0		= * + 35
y0		= * + 40
; Bytes
x		= * + 45
y		= * + 46
i		= * + 47