mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-11-20 03:35:24 +00:00
270 lines
5.9 KiB
ArmAsm
270 lines
5.9 KiB
ArmAsm
; Apple II Seasons -=DESiRE=- 128B Demo for Outline 2020
|
|
; based on the code in Hellmood's 64B x86 demo "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
|
|
; color-cycling brought it back up to 127 bytes
|
|
|
|
; To save space, runs from the zero page starting at $50
|
|
; need to avoid $E0-$E5 used by the hgr/hplot routines
|
|
|
|
; Zero Page Addresses
|
|
|
|
XCOORDL = $F3
|
|
XCOORDH = $F4
|
|
YCOORDL = $F5
|
|
YCOORDH = $F6
|
|
EBP1 = $F7
|
|
EBP2 = $F8
|
|
EBP3 = $F9
|
|
EBP4 = $FA
|
|
COLORL = $FB
|
|
COLORH = $FC
|
|
SOUND = $FD
|
|
FRAMEL = $FE
|
|
FRAMEH = $FF
|
|
|
|
; 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+
|
|
; or later to run
|
|
|
|
TEXT = $FB36 ; Set text mode
|
|
HGR2 = $F3D8 ; Set full-screen hi-res mode using page 2 ($4000)
|
|
; 280x192 6-colors
|
|
HPLOT0 = $F457 ; Plot point, (Y,X) = Horizontal, (A=Vertical)
|
|
HCOLOR = $F6EC ; Set color in X, must be 0..7
|
|
|
|
; use zero-page addressing to save space
|
|
.zeropage
|
|
|
|
seasons:
|
|
|
|
;===================
|
|
; init screen ; Instruction Length
|
|
jsr HGR2 ; 3
|
|
|
|
; init vars to zero. Apple II doesn't clear RAM
|
|
; 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
|
|
|
|
|
|
seasons_forever:
|
|
|
|
; save old Xcoord value to X/Y for later
|
|
; push/pop is 1 byte each but have to get
|
|
; value into accumulator first
|
|
ldx XCOORDL ; 2
|
|
ldy XCOORDH ; 2
|
|
|
|
; 16-bit subtraction x=x-y
|
|
; need to set carry before subtraction on 6502
|
|
txa ; 1 (xcoordl in X)
|
|
sec ; 1
|
|
sbc YCOORDL ; 2
|
|
sta XCOORDL ; 2
|
|
tya ; 1 (xcoordh in Y)
|
|
sbc YCOORDH ; 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 ; 1
|
|
sta XCOORDH ; 2
|
|
ror XCOORDL ; 2
|
|
|
|
; 16-bit add, ycoord=ycoord+oldx
|
|
clc ; 1
|
|
txa ; 1
|
|
adc YCOORDL ; 2
|
|
sta YCOORDL ; 2
|
|
tya ; 1
|
|
adc YCOORDH ; 2
|
|
|
|
; 16-bit arithmatic shift right of y-coord
|
|
cmp #$80 ; 2 ; YCOORDH still in A from before
|
|
ror ; 1
|
|
sta YCOORDH ; 2
|
|
ror YCOORDL ; 2
|
|
|
|
; 32 bit rotate of low bit shifted out of Y-coordinate
|
|
ror EBP1 ; 2
|
|
ror EBP2 ; 2
|
|
ror EBP3 ; 2
|
|
ror EBP4 ; 2
|
|
|
|
; branch if carry set
|
|
bcs label_11f ; 2
|
|
|
|
; 16-bit increment of color
|
|
inc COLORL ; 2
|
|
bne no_oflo ; 2
|
|
inc COLORH ; 2
|
|
no_oflo:
|
|
|
|
; 16-bit add of X-coord by 0x80
|
|
; this keeps the drawing roughly to the 280x192 screen
|
|
; carry should still be clear (inc doesn't set it)
|
|
lda XCOORDL ; 2
|
|
adc #$80 ; 2
|
|
sta XCOORDL ; 2
|
|
bcc no_oflo2 ; 2
|
|
inc XCOORDH ; 2
|
|
no_oflo2:
|
|
|
|
; 16-bit negate of Y-coord
|
|
sec ; 1
|
|
lda #0 ; 2
|
|
sbc YCOORDL ; 2
|
|
sta YCOORDL ; 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
|
|
smc:
|
|
ora #$2 ; 2
|
|
tax ; 1
|
|
|
|
; if using color lookup table
|
|
; tay ; 1
|
|
; ldx color_lookup,Y ; 3 (could be 2 if we run in zero page)
|
|
|
|
; if ycoord negative, loop
|
|
lda YCOORDH ; 2
|
|
bmi seasons_forever ; 2
|
|
|
|
; if top bits of xcoord, loop
|
|
lda XCOORDH ; 2
|
|
and #$f0 ; 2
|
|
bne seasons_forever ; 2
|
|
|
|
put_pixel:
|
|
|
|
; actually set the color
|
|
jsr HCOLOR ; 3 ; color is in X
|
|
|
|
; set up paramaters for HPLOT ROM call
|
|
ldx XCOORDL ; 2 ; x coord in (y:x)
|
|
ldy XCOORDH ; 2
|
|
lda YCOORDL ; 2 ; y coord in A
|
|
jsr HPLOT0 ; 3
|
|
|
|
; flip palettes when color at $4200 (roughly 0,32 on screen)
|
|
; changes. This is sort of arbitrary, but having a 16-bit counter
|
|
; takes too many instructions and Apple II doesn't have a
|
|
; programmable timer
|
|
|
|
lda $4200 ; 3 ; check colors at 0,32
|
|
bmi seasons_forever ; 2
|
|
|
|
; flip between blue/purple and orange/green palettes
|
|
; with self-modifying code. 2 bytes are saved when
|
|
; we execute in the zero page
|
|
lda smc+1 ; 2
|
|
eor #$3 ; 2
|
|
sta smc+1 ; 2
|
|
|
|
; the adc/sbc in HPLOT0 leave the V flag clear
|
|
; so we can save a byte (over jump) by using bvc
|
|
bvc seasons_forever ; 2
|
|
|
|
|
|
|
|
|
|
; Thankfully not necessary for a 128B demo?
|
|
; lda KEYPRESS ; 3 ; see if key pressed
|
|
; bpl seasons_forever ; 2 ; loop if not
|
|
; bit KEYRESET
|
|
exit_to_prompt:
|
|
; jsr TEXT ; 3 ; return to text mode
|
|
; jmp $3D0 ; 3 ; return to Applesoft prompt
|
|
|
|
|
|
;========================================================
|
|
;========================================================
|
|
; color lookup tables used when testing
|
|
; some of them look better, but make the executable bigger
|
|
; than the AND/OR version of setting colors
|
|
|
|
|
|
; Apple II Hi-Res Colors
|
|
; It's all NTSC artifacting and complex
|
|
; There can be color-clash at a 3.5 pixel level
|
|
; Adjacent on pixels make white, adjacent off make black
|
|
; Simplistic summary, you can have these 8 colors (6 unique)
|
|
; 0 = Black0
|
|
; 1 = Green
|
|
; 2 = Purple
|
|
; 3 = White0
|
|
; 4 = Black1
|
|
; 5 = Orange
|
|
; 6 = Blue
|
|
; 7 = White2
|
|
|
|
color_lookup:
|
|
|
|
; colorful palette
|
|
; .byte $01,$01,$02,$03, $05,$05,$06,$07
|
|
|
|
; blue and purple palette
|
|
; .byte $02,$02,$03,$06, $06,$06,$02,$07
|
|
|
|
; qkumba ora2 white/blue/purple
|
|
; .byte $02,$03,$02,$03, $06,$07,$06,$07
|
|
|
|
; ora1 white/orange/green
|
|
; .byte $01,$01,$03,$03, $05,$05,$07,$07
|
|
|
|
; better mixed orange/green/white
|
|
; .byte $01,$03,$03,$03, $05,$05,$07,$07
|
|
|
|
; orange and green palette
|
|
; .byte $01,$01,$03,$05, $05,$05,$01,$07
|
|
|
|
; .byte $01,$00,$01,$00, $05,$00,$05,$00
|
|
|
|
; "Leaf" Locations
|
|
; TOP-LEFT ?? CENTER-TOP TOP-RIGHT LEFT ?? CENTER-BOTTOM ??
|
|
|
|
|