dos33fsprogs/ootw/earthquake.s

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2019-01-20 06:05:52 +00:00
;==========================
; check for earthquake
earthquake_handler:
lda FRAMEH
and #3
bne earth_mover
lda FRAMEL
cmp #$ff
bne earth_mover
earthquake_init:
lda #200
sta EQUAKE_PROGRESS
lda #0
sta BOULDER_Y
jsr random16
lda SEEDL
and #$1f
clc
adc #4
sta BOULDER_X
earth_mover:
lda EQUAKE_PROGRESS
beq earth_still
and #$8
bne earth_calm
lda #2
bne earth_decrement
earth_calm:
lda #0
earth_decrement:
sta EARTH_OFFSET
dec EQUAKE_PROGRESS
jmp earth_done
earth_still:
lda #0
sta EARTH_OFFSET
earth_done:
;================================
; copy background to current page
lda EARTH_OFFSET
bne shake_shake
no_shake:
jsr gr_copy_to_current
jmp done_shake
shake_shake:
jsr gr_copy_to_current_BC00
2019-01-20 06:05:52 +00:00
done_shake:
rts
;======================
; draw falling boulders
draw_boulder:
lda BOULDER_Y
cmp #38
bpl no_boulder
lda #<boulder
sta INL
lda #>boulder
sta INH
lda BOULDER_X
sta XPOS
lda BOULDER_Y
sta YPOS
jsr put_sprite
lda FRAMEL
and #$3
bne no_boulder
inc BOULDER_Y
inc BOULDER_Y
no_boulder:
rts
;=========================================================
; gr_copy_to_current, 40x48 version
;=========================================================
; copy $BC00 to DRAW_PAGE
gr_copy_to_current_BC00:
lda DRAW_PAGE ; 3
clc ; 2
adc #$4 ; 2
sta gr_copy_line_BC+5 ; 4
sta gr_copy_line_BC+11 ; 4
adc #$1 ; 2
sta gr_copy_line_BC+17 ; 4
sta gr_copy_line_BC+23 ; 4
adc #$1 ; 2
sta gr_copy_line_BC+29 ; 4
sta gr_copy_line_BC+35 ; 4
adc #$1 ; 2
sta gr_copy_line_BC+41 ; 4
sta gr_copy_line_BC+47 ; 4
;===========
; 45
ldy #119 ; for early ones, copy 120 bytes ; 2
gr_copy_line_BC:
lda $BC00,Y ; load a byte (self modified) ; 4
sta $400,Y ; store a byte (self modified) ; 5
lda $BC80,Y ; load a byte (self modified) ; 4
sta $480,Y ; store a byte (self modified) ; 5
lda $BD00,Y ; load a byte (self modified) ; 4
sta $500,Y ; store a byte (self modified) ; 5
lda $BD80,Y ; load a byte (self modified) ; 4
sta $580,Y ; store a byte (self modified) ; 5
lda $BE00,Y ; load a byte (self modified) ; 4
sta $600,Y ; store a byte (self modified) ; 5
lda $BE80,Y ; load a byte (self modified) ; 4
sta $680,Y ; store a byte (self modified) ; 5
lda $BF00,Y ; load a byte (self modified) ; 4
sta $700,Y ; store a byte (self modified) ; 5
lda $BF80,Y ; load a byte (self modified) ; 4
sta $780,Y ; store a byte (self modified) ; 5
dey ; decrement pointer ; 2
bpl gr_copy_line_BC ; ; 2nt/3
rts ; 6