dos33fsprogs/megademo/starring.s
2018-10-18 13:53:37 -04:00

278 lines
4.6 KiB
ArmAsm

; Display Starring Message
; 1st screen = triple page flip
; 2nd/3rd = split low/hires
starring:
;===================
; init screen
jsr TEXT
jsr HOME
bit KEYRESET
;===================
; init vars
lda #0
sta FRAME
sta FRAMEH
sta DRAW_PAGE
;=============================
; Load graphic hgr
lda #<starring3
sta LZ4_SRC
lda #>starring3
sta LZ4_SRC+1
lda #<(starring3_end-8) ; skip checksum at end
sta LZ4_END
lda #>(starring3_end-8) ; skip checksum at end
sta LZ4_END+1
lda #<$2000
sta LZ4_DST
lda #>$2000
sta LZ4_DST+1
jsr lz4_decode
;=============================
; Load graphic page0
lda #$0c
sta BASH
lda #$00
sta BASL ; load image to $c00
lda #<starring1
sta GBASL
lda #>starring1
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
;=============================
; Load graphic page1
lda #$0c
sta BASH
lda #$00
sta BASL ; load image to $c00
lda #<starring2
sta GBASL
lda #>starring2
sta GBASH
jsr load_rle_gr
lda #0
sta DRAW_PAGE
jsr gr_copy_to_current
; GR part
bit PAGE0
;==============================
; 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
stloopA:ldx #9 ; 2
stloopB:dex ; 2
bne stloopB ; 2nt/3
dey ; 2
bne stloopA ; 2nt/3
jmp st_display_loop
.align $100
;================================================
; Starring Loop
;================================================
; just kill time, 65*192 = 12480
st_display_loop:
; Try X=15 Y=154 cycles=12475 R5
nop ; 2
lda $0 ; 3
ldy #154 ; 2
suloop1:ldx #15 ; 2
suloop2:dex ; 2
bne suloop2 ; 2nt/3
dey ; 2
bne suloop1 ; 2nt/3
;======================================================
; We have 4550 cycles in the vblank, use them wisely
;======================================================
; we want to flip between GR Page0, GR Page1, HGR Page0
; we want to flip at roughly 3Hz, so every 20 times through
; what if 16, for power-of-two easiness? 3.75Hz?
; FRAME== 0 GR/PAGE0
; FRAME==20 GR/PAGE1
; FRAME==40 HGR/PAGE0
; FRAME==60 reset
; default = 13+5+5+7 = 30
; sixty = 13+20 = 30
; forty = 13+5+12 = 30
; twenty = 13+5+5+7 = 30
inc FRAME ; 5
lda FRAME ; 3
cmp #60 ; 2
bne st_not_sixty ; 3
;===========
; 13
st_sixty: ; -1
lda #0 ; wrap frame counter ; 2
sta FRAME ; 3
bit LORES ; 4
bit PAGE0 ; 4
nop ; 2
jmp done_st_vblank ; 3
;===========
; 17
st_not_sixty:
cmp #20 ; 2
bne st_not_twenty ; 3
;============
; 5
st_twenty: ; -1
bit LORES ; 4
nop ; 2
st_seven_cycles:
bit PAGE1 ; 2C 55 C0, 55C0 = EOR $20,X (4 cyc) ; 4
jmp done_st_vblank ; 3
;============
; 12
st_not_twenty:
cmp #40 ; 2
bne st_seven_cycles+1 ; 3
;============
; 5
st_forty: ; -1
bit HIRES ; 4
bit PAGE0 ; 4
;============
; 7
done_st_vblank:
;================
; wrap counter
;================
; nowrap = 8+5=13
; wrap = 8+5=13
lda FRAME ; 3
cmp #40 ; ensure end on PAGE0 ; 2
beq st_wrap ; 3
st_nowrap:
;-1
lda $0 ; nop ; 3
bne st_wrap_done ; 3
st_wrap:
inc FRAMEH ; 5
st_wrap_done:
;==============
; timeout after 4s or so?
;==============
st_timeout:
lda FRAMEH ; 3
cmp #4 ; 2
beq st_done ; 3
; -1
;============
; 7
; do_nothing should be 4550
; -13 wrap
; -7 timeout
; -10 keypress
; -30 page flipping
; ===========
; 4484
; Try X=178 Y=5 cycles=4481 R3
lda $0
ldy #5 ; 2
stloop1:ldx #178 ; 2
stloop2:dex ; 2
bne stloop2 ; 2nt/3
dey ; 2
bne stloop1 ; 2nt/3
lda KEYPRESS ; 4
bpl st_no_keypress ; 3
jmp st_done
st_no_keypress:
jmp st_display_loop ; 3
st_done:
bit KEYRESET ; clear keypress ; 4
rts ; 6
;.include "starring1.inc"
;.include "starring2.inc"
;starring3:
;.incbin "starring3.img.lz4",11
;starring3_end: