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waterfall: vapor lock on sprite again

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This commit is contained in:
Vince Weaver 2018-08-02 16:55:03 -04:00
parent c0428150d4
commit 6477607753
1 changed files with 72 additions and 17 deletions
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89
waterfall/waterfall.s
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@ -16,6 +16,8 @@ MASK = $2E
COLOR = $30
FRAME = $60
BLARGH = $69
BIRD_STATE = $E0
BIRD_DIR = $E1
DRAW_PAGE = $EE
LASTKEY = $F1
PADDLE_STATUS = $F2
@ -52,11 +54,13 @@ waterfall_demo:
; init screen
jsr TEXT
jsr HOME
bit KEYRESET
bit PAGE0
;===================
; init vars
lda #0
sta BIRD_DIR
sta BIRD_STATE
lda #4
sta DRAW_PAGE
@ -223,15 +227,15 @@ page1_loop: ; delay 115+(7 loop)+4 (bit)+4(extra)
;======================================================
; 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
; -10 check for keypress
; 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
; -2214 draw sprite
; =============
; 67
; 28
jsr do_nothing ; 6
@ -287,34 +291,85 @@ draw_bird:
;====================
; Handle keypresses
; if no keypress, 9
; if keypress, 6+43 = 49
lda KEYPRESS ; 4
bpl no_keypress ; 3
jmp all_done
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
all_done:
jmp all_done
;===================================================
; 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 67-6 = 61 cycles to do it
; and take 28-6 = 22 cycles to do it
do_nothing:
; Try X=10 Y=1 cycles=57 R4
; Try X=3 Y=1 cycles=22
nop ; 2
nop ; 2
; nop ; 2
; nop ; 2
ldy #1 ; 2
loop1:
ldx #10 ; 2
ldx #3 ; 2
loop2:
dex ; 2
bne loop2 ; 2nt/3