Apple-2-SW/dos33fsprogs
1
0
Fork 0
mirror of https://github.com/deater/dos33fsprogs.git synced 2024-10-30 02:26:58 +00:00
Code Issues Projects Releases Wiki Activity
84b72e821e
dos33fsprogs/waterfall/waterfall.s

478 lines
8.9 KiB
ArmAsm
Raw Blame History

; Lo-res cycle-counting water transparency hack
; by deater (Vince Weaver) <vince@deater.net>
; Zero Page
FRAMEBUFFER = $00 ; $00 - $0F
YPOS = $10
YPOS_SIN = $11
CH = $24
CV = $25
GBASL = $26
GBASH = $27
BASL = $28
BASH = $29
MASK = $2E
COLOR = $30
FRAME = $60
BIRD_STATE = $E0
BIRD_DIR = $E1
DRAW_PAGE = $EE
LASTKEY = $F1
PADDLE_STATUS = $F2
XPOS = $F3
TEMP = $FA
TEMPY = $FB
INL = $FC
INH = $FD
OUTL = $FE
OUTH = $FF
; Soft Switches
KEYPRESS= $C000
KEYRESET= $C010
SET_GR = $C050 ; Enable graphics
FULLGR = $C052 ; Full screen, no text
PAGE0 = $C054 ; Page0
PAGE1 = $C055 ; Page1
LORES = $C056 ; Enable LORES graphics
PADDLE_BUTTON0 = $C061
PADDL0 = $C064
PTRIG = $C070
; ROM routines
TEXT = $FB36 ;; Set text mode
HOME = $FC58 ;; Clear the text screen
WAIT = $FCA8 ;; delay 1/2(26+27A+5A^2) us
waterfall_demo:
;===================
; init screen
jsr TEXT
jsr HOME
bit PAGE0
;===================
; init vars
lda #0
sta BIRD_DIR
sta BIRD_STATE
lda #4
sta DRAW_PAGE
sta XPOS
;=============================
; Load foreground to graphic page1 (apple page2)
lda #$0c
sta BASH
lda #$00
sta BASL ; load image to $c00
lda #<waterfall_page1
sta GBASL
lda #>waterfall_page1
sta GBASH
jsr load_rle_gr
jsr gr_copy_to_current ; copy to page1
;=============================
; Load bg to memory
lda #$0c
sta BASH
lda #$00
sta BASL ; load image to $c00
lda #<waterfall_page2
sta GBASL
lda #>waterfall_page2
sta GBASH
jsr load_rle_gr
;==============================
; setup graphics for vapor lock
;==============================
; Clear Page0
lda #$0
sta DRAW_PAGE
lda #$44
jsr clear_gr
; Make screen half green
lda #$11
ldy #24
jsr clear_page_loop
;=====================================================
; attempt vapor lock
; by reading the "floating bus" we can see most recently
; written value of the display
; we look for $55 (which is the grey line)
;=====================================================
; See:
; Have an Apple Split by Bob Bishop
; Softalk, October 1982
; Challenges: each scan line scans 40 bytes.
; The blanking happens at the *beginning*
; So 65 bytes are scanned, starting at adress of the line - 25
; the scan takes 8 cycles, look for 4 repeats of the value
; to avoid false positive found if the horiz blanking is mirroring
; the line (max 3 repeats in that case)
vapor_lock_loop: ; first make sure we have all zeroes
LDA #$11
zxloop:
LDX #$04
wiloop:
CMP $C051
BNE zxloop
DEX
BNE wiloop
LDA #$44 ; now look for our border color (4 times)
zloop:
LDX #$04
qloop:
CMP $C051
BNE zloop
DEX
BNE qloop
; found first line of black after green, at up to line 26 on screen
; so we want roughly 22 lines * 4 = 88*65 = 5720 + 4550 = 10270
; - 65 (for the scanline we missed) = 10205 - 12 = 10193
jsr gr_copy_to_current ; 6+ 9292
; 10193 - 9298 = 895
; Fudge factor (unknown) -30 = 865
; GR part
bit LORES ; 4
bit SET_GR ; 4
bit FULLGR ; 4
; Try X=88 Y=2 cycles=893 R2
nop
ldy #2 ; 2
loopA:
ldx #88 ; 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 #96 ; 2
outer_loop:
bit PAGE0 ; 4
ldx #12 ; 65 cycles with PAGE0 ; 2
page0_loop: ; delay 61+bit
dex ; 2
bne page0_loop ; 2/3
; bit(4) -1(fallthrough) + loop*5 -1(fallthrouh)+4 extra = 61
; 5L = 55
bit PAGE1 ; 4
ldx #11 ; 65 cycles with PAGE1 ; 2
;
page1_loop: ; delay 115+(7 loop)+4 (bit)+4(extra)
dex ; 2
bne page1_loop ; 2/3
dey ; 2
bne outer_loop ; 2/3
;======================================================
; We have 4550 cycles in the vblank, use them wisely
;======================================================
; do_nothing should be 4550
; +1 fallthrough from above
; -2 display loop setup
; -6 jsr to do_nothing
; -49 check for keypress
; -2252 copy screen
; -2231 draw sprite
; =============
; 11 cycles
; jsr do_nothing ; 6
; 17 cycles
inc YPOS ; 5
inc YPOS ; 5
inc YPOS ; 5
nop ; 2
;=========================
; Clear background
;=========================
jsr gr_copy_row22 ; 6+ 2246
;=========
; 2252
;==========================
; draw bird sprite
;==========================
; 8 prefix
; bird_walk_right= 14 + 2175 2206 (need 17)
; bird_stand_right= 13 + 2190 2206 (need 3)
; bird_walk_left= 15 + 2175 2206 (need 16)
; bird_stand_left= 14 + 2190 2206 (need 2)
; call to sprite 17 postfix
;====================================================
; 2231
lda BIRD_STATE ; 3
and #1 ; 2
ldx BIRD_DIR ; 3
bne bird_left
bird_right:
; 2
cmp #1 ; 2
beq bird_walk_right
; 2
bird_stand_right:
ldx #>bird_rider_stand_right ; 2
ldy #<bird_rider_stand_right ; 2
lda YPOS ; nop=3
jmp draw_bird ; 3
bird_walk_right:
; 3
ldx #>bird_rider_walk_right ; 2
ldy #<bird_rider_walk_right ; 2
jmp kill_less_time ; 3
bird_left:
; 3
cmp #1 ; 2
beq bird_walk_left
bird_stand_left:
; 2
ldx #>bird_rider_stand_left ; 2
ldy #<bird_rider_stand_left ; 2
nop ; nop=2
jmp draw_bird ; 3
bird_walk_left:
; 3
ldx #>bird_rider_walk_left ; 2
ldy #<bird_rider_walk_left ; 2
kill_time:
nop ; 2 ; need to kill 16
kill_less_time:
lda YPOS ; nop=3 ; need to kill 14
lda YPOS ; nop=3
lda YPOS ; nop=3
lda YPOS ; nop=3
nop ; 2
jmp draw_bird ; 3
draw_bird:
stx INH ; 3
sty INL ; 3
lda #22 ; 2
sta YPOS ; 3
jsr put_sprite ; 6
;=========
; 17 + 2190
;====================
; Handle keypresses
; if no keypress, 9
; if keypress, 6+43 = 49
lda KEYPRESS ; 4
bmi keypress
; 2
no_keypress:
; kill 40 cycles
ldx #0 ; 2
inc YPOS,X ; 6
inc YPOS,X ; 6
inc YPOS,X ; 6
inc YPOS,X ; 6
inc YPOS,X ; 6
inc YPOS,X ; 6
nop ; 2
jmp display_loop ; 3
;===================================================
; key was pressed handling takes 12 + 20 + 11 = 43
keypress:
; 1
bit KEYRESET ; 4
inc BIRD_STATE ; 5
and #$5f ; mask keypress ; 2
is_it_right:
cmp #$15 ; right arrow ; 2
bne is_it_left
; 2
inc XPOS ; 5
lda #0 ; 2
sta BIRD_DIR ; 3
lda YPOS ; 3-cycle nop ; 3
convoluted:
jmp adjust_xpos ; 3 ; 20 if right
is_it_left:
; 5
cmp #$8 ; left arrow ; 2
beq is_left
; 2
nop ; 2
lda YPOS ; 3-cycle nop
jmp convoluted ; 3
; ------ 20 if neither
is_left:
; 3
dec XPOS ; 5 ; 20 if left
lda #1 ; 2
sta BIRD_DIR ; 3
adjust_xpos:
lda XPOS ; 3
and #$1f ; keep in 0-31 range ; 2
sta XPOS ; 3
jmp display_loop ; 3
;=================================
; do nothing
;=================================
; and take 11-6 = 5 cycles to do it
;do_nothing:
; Try X=3 Y=1 cycles=22
; nop ; 2
; nop ; 2
; ldy #1 ; 2
;loop1:
; ldx #3 ; 2
;loop2:
; dex ; 2
; bne loop2 ; 2nt/3
; dey ; 2
; bne loop1 ; 2nt/3
; rts ; 6
;==================================
; HLINE
;==================================
; Color in A
; Y has which line
hline:
pha ; 3
ldx gr_offsets,y ; 4+
stx hline_loop+1 ; 4
lda gr_offsets+1,y ; 4+
clc ; 2
adc DRAW_PAGE ; 3
sta hline_loop+2 ; 4
pla ; 4
ldx #39 ; 2
hline_loop:
sta $5d0,X ; 38 ; 5
dex ; 2
bpl hline_loop ; 2nt/3
rts ; 6
;==========================
; Clear gr screen
;==========================
; Color in A
clear_gr:
ldy #46
clear_page_loop:
jsr hline
dey
dey
bpl clear_page_loop
rts
gr_offsets:
.word $400,$480,$500,$580,$600,$680,$700,$780
.word $428,$4a8,$528,$5a8,$628,$6a8,$728,$7a8
.word $450,$4d0,$550,$5d0,$650,$6d0,$750,$7d0
.include "../asm_routines/gr_unrle.s"
.include "../asm_routines/keypress.s"
.include "gr_copy.s"
.include "gr_unrolled_copy.s"
.include "put_sprite.s"
.include "waterfall_page1.inc"
.include "waterfall_page2.inc"
.align $100
.include "tfv_sprites.inc"
Reference in New Issue View Git Blame Copy Permalink