dos33fsprogs/demos/l/flyer_512/flyer.s
2022-01-09 18:10:45 -05:00

219 lines
3.3 KiB
ArmAsm

; Flyer
; by Vince `deater` Weaver, vince@deater.net --- d e s i r e ---
; 178 bytes -- original conversion from BASIC
; 176 bytes -- know HGR2 returns with A=0
; 172 bytes -- optimize page flip code
; 170 bytes -- assume XDRAW never got over X=256
; zero page locations
HGR_COLOR = $E4
HGR_PAGE = $E6
HGR_SCALE = $E7
HGR_ROTATION = $F9
HORIZON_Y = $FD
HORIZON_LINE = $FE
FRAME = $FF
; soft-switches
PAGE1 = $C054
PAGE2 = $C055
; ROM calls
HGR2 = $F3D8 ; after: A=0, Y=0, HGR_SHAPE=$40/$60
HCLR = $F3F2 ; clear current page to 0
BKGND0 = $F3F4 ; clear current page to A
HPOSN = $F411 ; move to (Y,X), (A) (saves A,X,Y to zero page)
HPLOT0 = $F457 ; plot at (Y,X), (A) (calls HPOSN)
HGLIN = $F53A ; line to (X,A), (Y)
DRAW0 = $F601
XDRAW0 = $F65D
flyer:
jsr HGR2 ; HGR2 HGR_PAGE=$40
sta FRAME ; A=0 after HGR2
animate_loop:
clc
lda #96
adc FRAME
sta HORIZON_LINE ; S=96+FRAME
; flip draw page $20/$40
lda HGR_PAGE
eor #$60
sta HGR_PAGE
; flip page
; have $20/$40 want to map to C054/C055
asl
asl ; $20 -> C=1 $00
asl ; $40 -> C=0 $00
adc #0
tax
cmp PAGE1,X
; clear screen
jsr HCLR
;===============
; draw mountain
; FIXME: we in theory only have to do this once
; as we never over-write it
; color = blue (6)
lda #$D5
sta HGR_COLOR
; HPLOT 0,96 TO 140,80
ldy #0
ldx #0
lda #96
jsr HPLOT0 ; plot at (Y,X), (A)
ldx #0
lda #140
ldy #80
jsr HGLIN ; line to (X,A),(Y)
; HPLOT TO 279,96
ldx #1
lda #23
ldy #96
jsr HGLIN
; color = green (1)
lda #$2A
sta HGR_COLOR
horizon_lines_loop:
lsr HORIZON_LINE ; S=S/2:Y=96+S
clc
lda #96
adc HORIZON_LINE
sta HORIZON_Y
; HPLOT 0,Y TO 279,Y
ldy #0
ldx #0
lda HORIZON_Y
jsr HPLOT0 ; plot at (Y,X), (A)
ldx #1
lda #23
ldy HORIZON_Y
jsr HGLIN ; line to (X,A),(Y)
;================
; draw wicket
; XDRAW 1 AT 140,Y
lda HORIZON_LINE
lsr
lsr ; SCALE=1+S/5
clc
adc #1
sta HGR_SCALE
; ldy #0
ldx #140
lda HORIZON_Y
jsr xdraw
lda HORIZON_LINE
bne horizon_lines_loop ; IF S>1 THEN 8
;===================
; draw ship
; XDRAW 1 AT 140+16*SIN(H),180
lda #2
sta HGR_SCALE ; SCALE=2
lda FRAME
and #$f
clc
adc 140
; ldy #0
tax
lda #180
jsr xdraw
; H=H+0.3
; J=(J+12)*(J<84)
lda FRAME
cmp #84
bcs reset_frame
clc
adc #12
bne done_frame
reset_frame:
lda #0
done_frame:
sta FRAME
jmp animate_loop
;=======================
; xdraw
;=======================
xdraw:
; setup X and Y co-ords
ldy #0 ; XPOSH always 0 for us
; ldx XPOS
; lda YPOS
jsr HPOSN ; X= (y,x) Y=(a)
ldx #<ship_table
ldy #>ship_table
; lda #$7f
; sta HGR_COLOR
lda #0 ; set rotation
jsr XDRAW0 ; XDRAW 1 AT X,Y
; Both A and X are 0 at exit
rts
; optimize, can probably shave byte off
; was originally in ASCII for basic bot purposes
; "#%%-...",0
; but we don't have that limitation
ship_table:
.byte $23 ; 00 100 011 NLT UP X
.byte $25 ; 00 100 101 RT UP X
.byte $25 ; 00 100 101 RT UP X
.byte $2D ; 00 101 101 RT RT X
.byte $2E ; 00 101 110 DN RT X
.byte $2E ; 00 101 110 DN RT X
.byte $0E ; 00 001 110 DN RT X
.byte $0
; .byte $23 ; 00 100 011 NLT UP X
; .byte $25 ; 00 100 101 RT UP X
; .byte $25 ; 00 100 101 RT UP X
; .byte $2D ; 00 101 101 RT RT X
; .byte $2E ; 00 101 110 DN RT X
; .byte $2E ; 00 101 110 DN RT X
; .byte $2E ; 00 101 110 DN RT X
; .byte $0