dos33fsprogs/textmode/notamoon/notamoon.s
2021-03-01 12:56:56 -05:00

175 lines
2.8 KiB
ArmAsm

; That's not a moon....
; by Vince `deater` Weaver, dSr, Lovebyte 2021
; based on the following BASIC program
; 1HOME:POKE49167,0
; 2FORX=0TO64:POKE1024+RND(1)*999,174:NEXT
; 3FORI=0TO1:COLOR=6-I:FORJ=0TO1
; 4HLIN8,10AT6+J*10+I:HLIN7,11AT8+J*6+I:HLIN6,12AT10+J*2+I:NEXTJ,I
; 6VTAB6:HTAB11:?"()"
; 7FORX=13TO37:POKE1063+X,90:POKE1064+X,91:POKE1065+X,95
; 8FORI=1TO200:NEXT:VTAB9:HTABX:?" ":NEXT
; 9GOTO7
; 167 -- initial implementation
; 170 -- smooth grey support
; 152 -- make death star data byte array
; 148 -- make death star VTAB not hardcoded
; 144 -- move to zero page
; 136 -- index into ROM for "random" numbers
; 133 -- optimize star placement
; 131 -- note when X already 0
; 130 -- optimize tie erase
; 126 -- more optimize death star drawing
; 124 -- use the DEC CV the instruction before VTAB
; need 124 for lovebyte
; zero page
CV = $25
BASL = $28
BASH = $29
SEEDL = $4E
INL = $66
INH = $67
; soft-switches
MOUSETEXT = $C00F ; (write) to enable mouse text
; rom routines
HOME = $FC58 ; Clear the text screen
WAIT = $FCA8 ; delay 1/2(26+27A+5A^2) us
VTAB = $FC22 ; calc screen position in CV, put in (BASL)
VTABZ = $FC24 ; calc screen position in A, put in (BASL)
.zeropage
.globalzp grey_smc,ds_data,star_store_smc,tie_data
;=======================
; Clear screen and setup
;=======================
sw:
jsr HOME ; clear the screen
sta MOUSETEXT ; enable mouse text
;=======================
; Display Stars
;=======================
ldx #64
star_loop:
lda $F100,X
eor $F300,X ; fake random
tay
lda $F800,X
eor $F900,X ; more fake random
and #$3
ora #$4
sta star_store_smc+2
lda #'.'|$80
star_store_smc:
sta $400,Y
dex
bne star_loop
;=======================
; Display Death Star
;=======================
; ldx #0 ; X already 0
lda #9 ; count backwards
sta CV
ds_loop:
;============================
; draw grey line
;============================
grey_line:
jsr $FC20 ; this is a DEC CV line before VTAB
; jsr VTAB ; position VTAB based on CV
sec
lda #19
sbc ds_data,X
sta grey_smc+1
ldy ds_data,X
; inx
; lda ds_data,X
; sta grey_smc+1
inx
grey_loop:
clc
tya
and #$1
adc #$56 ; make it an even grey
sta (BASL),Y
iny
grey_smc:
cpy #0
bne grey_loop
; inc CV
cpx #6
bne ds_loop
; draw reflector
lda #'('+$80 ; 5,10?
sta $68A
lda #')'+$80 ; 5,11?
sta $68B
;=======================
; Draw Tie Fighter
;=======================
tie_loop:
ldy #12
tie_move:
; draw tie
ldx #2
xloop1:
lda tie_data,X
sta $428,Y ; line 8 (vtab 9)
iny
dex
bpl xloop1
; delay a bit
lda #200
jsr WAIT
; erase
lda #$A0 ; space (the final frontier)
xloop2:
dey
sta $428,Y ; line 8 (vtab 9)
inx
cpx #2
bne xloop2
iny
cpy #38
bne tie_move
beq tie_loop
tie_data:
.byte 95,91,90
ds_data:
.byte 8;,11
.byte 7;,12
.byte 6;,13
.byte 6;,13
.byte 7;,12
.byte 8;,11