dos33fsprogs/megademo/falling_apple.s
Vince Weaver 3029d4220b megademo: hook up improved vapor lock
still issues :(
2018-09-21 00:33:51 -04:00

201 lines
3.4 KiB
ArmAsm

; Display Falling Apple II and message
falling_apple:
;===================
; init screen
jsr TEXT
jsr HOME
bit KEYRESET
;===================
; init vars
lda #0
sta DRAW_PAGE
;=============================
; Load graphic page0
lda #$0c
sta BASH
lda #$00
sta BASL ; load image to $c00
lda #<apple_low
sta GBASL
lda #>apple_low
sta GBASH
jsr load_rle_gr
lda #4
sta DRAW_PAGE
jsr gr_copy_to_current ; copy to page1
; GR part
bit PAGE1
bit LORES ; 4
bit SET_GR ; 4
bit FULLGR ; 4
; jsr wait_until_keypressed
;=============================
; Load graphic page1
lda #$0c
sta BASH
lda #$00
sta BASL ; load image to $c00
lda #<apple_high
sta GBASL
lda #>apple_high
sta GBASH
jsr load_rle_gr
lda #0
sta DRAW_PAGE
jsr gr_copy_to_current
; GR part
bit PAGE0
; jsr wait_until_keypressed
;==============================
; setup graphics for vapor lock
;==============================
jsr vapor_lock ; 6
; vapor lock returns with us at beginning of hsync in line
; 114 (7410 cycles), so with 5070 lines to go
jsr gr_copy_to_current ; 6+ 9292
; now we have 322 left
; GR part
bit LORES ; 4
bit SET_GR ; 4
bit FULLGR ; 4
; 322 - 12 = 310
; - 3 for jmp
; 307
; Try X=9 Y=6 cycles=307
ldy #6 ; 2
loopA:
ldx #9 ; 2
loopB:
dex ; 2
bne loopB ; 2nt/3
dey ; 2
bne loopA ; 2nt/3
jmp display_loop
.align $100
;================================================
; Display Loop
;================================================
; each scan line 65 cycles
; 1 cycle each byte (40cycles) + 25 for horizontal
; Total of 12480 cycles to draw screen
; Vertical blank = 4550 cycles (70 scan lines)
; Total of 17030 cycles to get back to where was
; We want to alternate between page1 and page2 every 65 cycles
; vblank = 4550 cycles to do scrolling
; 2 + 48*( (4+2+25*(2+3)) + (4+2+23*(2+3)+4+5)) + 9)
; 48*[(6+125)-1] + [(6+115+10)-1]
display_loop:
ldy #48 ; 2
outer_loop:
bit PAGE0 ; 4
ldx #25 ; 130 cycles with PAGE0 ; 2
page0_loop: ; delay 126+bit
dex ; 2
bne page0_loop ; 2/3
bit PAGE1 ; 4
ldx #23 ; 130 cycles with PAGE1 ; 2
page1_loop: ; delay 115+(7 loop)+4 (bit)+4(extra)
dex ; 2
bne page1_loop ; 2/3
nop ; 2
lda DRAW_PAGE ; 3
dey ; 2
bne outer_loop ; 2/3
;======================================================
; We have 4550 cycles in the vblank, use them wisely
;======================================================
; do_nothing should be 4550+1 -2-9 -7= 4533
jsr do_nothing ; 6
lda KEYPRESS ; 4
bpl no_keypress ; 3
jmp start_over
no_keypress:
jmp display_loop ; 3
start_over:
rts
;=================================
; do nothing
;=================================
; and take 4533-6 = 4527 cycles to do it
do_nothing:
; Try X=4 Y=174 cycles=4525 R2
nop ; 2
ldy #174 ; 2
loop1:
ldx #4 ; 2
loop2:
dex ; 2
bne loop2 ; 2nt/3
dey ; 2
bne loop1 ; 2nt/3
rts ; 6
.include "../asm_routines/gr_unrle.s"
.include "gr_copy.s"
.include "apple_40_96.inc"