Files
dos33fsprogs/vaporlock/demo/midline.s
2023-05-17 23:40:52 -04:00

265 lines
5.3 KiB
ArmAsm

; Blargh
; by Vince `deater` Weaver
.include "zp.inc"
.include "hardware.inc"
; 198 bytes -- proof of concept
; 76 bytes -- optimize Apple II Forever printing code
; 183 bytes -- stable window
midline:
;================================
; Clear screen and setup graphics
;================================
sta FULLGR
sta SETMOUSETEXT
jsr initSineTable
;====================================================
; setup text page1 screen of "Apple II Forever" text
;====================================================
ldy #0
restart:
ldx #0
iny
beq print_done
print_loop:
lda a2_string,X
beq restart
jsr COUT ; output char in A to stdout
inx
bne print_loop
print_done:
;==================================
; get exact vblank region
;==================================
; code by Sather
; "Understanding the Apple IIe"
poll1:
lda VBLANK ; Find end of VBL
bmi poll1 ; Fall through at VBL
poll2:
lda VBLANK
bpl poll2 ; Fall through at VBL' ; 2
lda $00 ; Now slew back in 17029 cycle loops ; 3
lp17029:
ldx #17 ; ; 2
jsr waitx1k ; ; 17000
jsr rts1 ; ; 12
lda $00 ; nop3 ; 3
lda $00 ; nop3 ; 3
lda VBLANK ; Back to VBL yet? ; 4
nop ; ; 2
bmi lp17029 ; no, slew back ; 2/3
;==============================
; do the cycle counting
;==============================
blog:
; 192 + 70 (vblank) = 262
; if 42 high, then day 220 on, 42 off
; how start in middle?
; .byte $A5
lda $EA ; nop3 ; 3
; nop ; 2
ldx #20 ; 2
bne top8 ; bra ; 3/2
top_loop:
nop ; 2
nop ; 2
blog_loop:
nop ; 2
nop ; 2
; 8
top8:
jsr delay_16_setgr ; 16
; 24
jsr delay_16_setgr ; 16
; 40
jsr delay_16_setgr ; 16
; 56
nop ; 2
nop ; 2
; 60
dex ; 2
bne top_loop ; 3
; -1
nop ; 2
nop ; 2
ldx #64 ; 2
bne middle_8 ; bra ; 3
middle_loop:
nop ; 2
nop ; 2
nop ; 2
nop ; 2
; 8
middle_8:
jsr delay_16_setgr ; 16
; 24
jsr delay_16_settext ; 16
; 40
jsr delay_16_setgr ; 16
; 56
nop ; 2
nop ; 2
; 60
dex ; 2
bne middle_loop ; 3/2
; -1
nop ; 2
nop ; 2
ldx #178 ; 2
bne bottom_8 ; 3/2
bottom_loop:
nop ; 2
nop ; 2
nop ; 2
nop ; 2
; 8
bottom_8:
jsr delay_16_setgr ; 16
; 24
jsr delay_16_setgr ; 16
; 40
jsr delay_16_setgr ; 16
; 56
nop ; 2
nop ; 2
; 60
dex ; 2
bne bottom_loop ; 3/2
; -1
ldx #20 ; 2
jmp blog_loop ; 3
delay_16_setgr:
bit SET_GR
delay_12:
rts
delay_16_settext:
bit SET_TEXT
rts
;===================================
; wait y-reg times 10
;===================================
loop10:
bne skip
waitx10:
dey ; wait y-reg times 10 ; 2
skip:
dey ; 2
nop ; 2
bne loop10 ; 2/3
rts ; 6
;===================================
; wait x-reg times 1000
;===================================
loop1k:
pha ; 3
pla ; 4
nop ; 2
nop ; 2
waitx1k:
ldy #98 ; wait x-reg times 1000 ; 2
jsr waitx10 ; 980
nop ; 2
dex ; 2
bne loop1k ; 2/3
rts1:
rts ; 6
a2_string:
; 012345678901234567 8 9
; .byte "Apple II Forever!! ",'@'+$80," ",0
.byte 'A'+$80,'p'+$80,'p'+$80,'l'+$80,'e'+$80,' '+$80
.byte 'I'+$80,'I'+$80,' '+$80,'F'+$80,'o'+$80,'r'+$80
.byte 'e'+$80,'v'+$80,'e'+$80,'r'+$80,'!'+$80,'!'+$80
.byte ' '+$80,'@'+$00,' '+$80,0
initSineTable:
ldy #$3f
ldx #$00
; Accumulate the delta (normal 16-bit addition)
:
lda value
clc
adc delta
sta value
lda value+1
adc delta+1
sta value+1
; Reflect the value around for a sine wave
sta sine+$c0,x
sta sine+$80,y
eor #$7f
sta sine+$40,x
sta sine+$00,y
; Increase the delta, which creates the "acceleration" for a parabola
lda delta
; adc #$10 ; this value adds up to the proper amplitude
adc #$08 ; this value adds up to the proper amplitude
sta delta
bcc :+
inc delta+1
:
; Loop
inx
dey
bpl :--
rts
value: .word 0
delta: .word 0
sine = $c00