autumn: made smaller by qkumba

This commit is contained in:
Vince Weaver 2020-05-11 17:11:18 -04:00
parent 83219ff84b
commit 25436f888a

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@ -1,6 +1,11 @@
; Autumn, based on the code in Hellmood's Autumn
; by deater (Vince Weaver) <vince@deater.net>
; DOS version is 64 bytes
; original Apple II 6502 port was 167 bytes
; I got it down to 126 bytes
; qkumba got it down to 116
; Zero Page Addresses
XCOORDL = $F0
@ -13,10 +18,12 @@ EBP3 = $F6
EBP4 = $F7
COLORL = $F8
COLORH = $F9
SOUND = $FA
; Soft Switches
KEYPRESS= $C000
KEYRESET= $C010
SPEAKER = $C030
; ROM routines
; Some of these are in the Applesoft ROMs so need at least an Apple II+
@ -28,6 +35,7 @@ HGR2 = $F3D8 ; Set full-screen hi-res mode using page 2 ($4000)
HPLOT0 = $F457 ; Plot point, (Y,X) = Horizontal, (A=Vertical)
HCOLOR = $F6EC ; Set color in X, must be 0..7
XDRAW1 = $F661
autumn:
@ -36,31 +44,23 @@ autumn:
jsr HGR2 ; 3
; init vars to zero. Apple II doesn't clear RAM
; some of these might not be necessary
; should make this a loop
ldx #0 ; 2
stx XCOORDL ; 2
stx YCOORDL ; 2
stx XCOORDH ; 2
stx YCOORDH ; 2
stx EBP1 ; 2
stx EBP2 ; 2
stx EBP3 ; 2
stx EBP4 ; 2
stx COLORH ; 2
; some of these might be necessary?
; should we make this a loop?
; ldx #0 ; 2
; stx XCOORDL ; 2
; stx YCOORDL ; 2
; stx XCOORDH ; 2
; stx YCOORDH ; 2
; stx EBP1 ; 2
; stx EBP2 ; 2
; stx EBP3 ; 2
; stx EBP4 ; 2
; stx COLORH ; 2
; not necessary? on x86 is probably the
; result of the VESA BIOS call
; lda #$4f
; sta COLORL
autumn_forever:
; 16-bit shift of color
; 2nd is a rotate as asl doesn't shift in cary
asl COLORL ; 2 ; shl %ax
rol COLORH ; 2
; save old Xcoord value to X/Y for later
; push/pop is 1 byte each but have to get
; value into accumulator first
@ -69,19 +69,19 @@ autumn_forever:
; 16-bit subtraction x=x-y
; need to set carry before subtraction on 6502
txa ; 1 (xcoordl in X)
sec ; 1
lda XCOORDL ; 2
sbc YCOORDL ; 2
sta XCOORDL ; 2
lda XCOORDH ; 2
tya ; 1 (xcoordh in Y)
sbc YCOORDH ; 2
sta XCOORDH ; 2
; 16-bit arithmatic shift right of X
; 6502 has no asr instruction
; cmp #$80 sets carry if high bit set
cmp #$80 ; 2 ; XCOORDH still in A from before
ror XCOORDH ; 2
ror ; 1
sta XCOORDH ; 2
ror XCOORDL ; 2
; 16-bit add, ycoord=ycoord+oldx
@ -91,11 +91,11 @@ autumn_forever:
sta YCOORDL ; 2
tya ; 1
adc YCOORDH ; 2
sta YCOORDH ; 2
; 16-bit arithmatic shift right of y-coord
cmp #$80 ; 2 ; YCOORDH still in A from before
ror YCOORDH ; 2
ror ; 1
sta YCOORDH ; 2
ror YCOORDL ; 2
; 32 bit rotate of low bit shifted out of Y-coordinate
@ -119,25 +119,47 @@ no_oflo:
lda XCOORDL ; 2
adc #$80 ; 2
sta XCOORDL ; 2
lda XCOORDH ; 2
adc #$0 ; 2
sta XCOORDH ; 2
bcc no_oflo2 ; 2
inc XCOORDH ; 2
no_oflo2:
; 16-bit negate of Y-coord
sec ; 1
lda YCOORDL ; 2
eor #$FF ; 2
adc #$0 ; 2
lda #0 ; 2
sbc YCOORDL ; 2
sta YCOORDL ; 2
lda YCOORDH ; 2
eor #$FF ; 2
adc #$0 ; 2
lda #0 ; 2
sbc YCOORDH ; 2
sta YCOORDH ; 2
label_11f:
; skipping the color manipulation done here by original
; mix colors a bit?
; 16-bit shift of color
; 2nd is a rotate as asl doesn't shift in cary
lda COLORL ; 2
asl ; 1 ; shl %ax
rol COLORH ; 2
eor COLORH ; 2
sta COLORL ; 2
; get color mapping
; using a color lookup table looks best but too many bytes
; you can approximate something close to the lookup with
; two extra instructions
and #$7 ; 2
ora #$2 ; 2
tax ; 1
; if using color lookup table
; tay ; 1
; ldx color_lookup,Y ; 3 (could be 2 if we run in zero page)
; if ycoord negative, loop
lda YCOORDH ; 2
bmi autumn_forever ; 2
@ -147,14 +169,7 @@ label_11f:
and #$f0 ; 2
bne autumn_forever ; 2
put_pixel:
; get color mapping
; using lookup table for now while trying to find best combo
lda COLORL ; 2
and #$7 ; 2
tay ; 1
ldx color_lookup,Y ; 3 (could be 2 if we run in zero page)
; actually set the color
jsr HCOLOR ; 3
@ -165,16 +180,18 @@ put_pixel:
lda YCOORDL ; 2
jsr HPLOT0 ; 3
lda KEYPRESS ; 3 ; see if key pressed
; bpl autumn_forever ; loop if not
; lda KEYPRESS ; 3 ; see if key pressed
; bpl autumn_forever ; 2 ; loop if not
bvc autumn_forever ; 2 ; smaller than jump
; V flag clear because
; the adc/sbc in HPOSN
; never overflows?
bmi exit_to_prompt ; 2 ; jump target too far away
jmp autumn_forever ; 3 ; if we get under 128 bytes
; can use the smaller jump
exit_to_prompt:
jsr TEXT ; 3 ; return to text mode
jmp $3D0 ; 3 ; return to Applesoft prompt
; jsr TEXT ; 3 ; return to text mode
; jmp $3D0 ; 3 ; return to Applesoft prompt
; Apple II Hi-Res Colors
@ -196,12 +213,31 @@ color_lookup:
; my default, colorful palette
; .byte $01,$01,$02,$03, $05,$05,$06,$07
; or 10
; 0000 0010 2 2
; 0001 0011 3 2
; 0010 0010 2 3
; 0011 0011 3 6
; 0100 0110 6 6
; 0101 0111 7 6
; 0110 0110 6 2
; 0111 0111 7 7
; want eor1
; 0000 0010 0001
; 0001 0010 0000
; 0010 0011 0011
; 0011 0110 0010
; 0100 0110 0101
; 0101 0110 0100
; 0110 0010 0111
; 0111 0111 0110
; blue and purple palette
; .byte $02,$02,$03,$06, $06,$06,$02,$07
; orange and green palette
.byte $01,$01,$03,$05, $05,$05,$01,$07
; .byte $01,$01,$03,$05, $05,$05,$01,$07
; "Leaf" Locations