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; explosion seen when we're hit by enemy fire.
; this draws something that looks a bit like TV static, only
; it's a lot more regular and less random. it somewhat approximates
; the apple version's explosion, but not all that closely.
.export _explosion
.include "atari.inc"
.importzp tmp1, tmp2
.import _jsleep
static_loop_count = tmp1
; extern void explosion(void);
; {
_explosion:
ldy #3 ; explosion_loop counter, counts 3 2 1
; {
@explosion_loop:
lda #$05 ; static_loop runs 3 times
sta static_loop_count
; {
@static_loop:
ldx #0 ; jsleep(2)
lda #$01
jsr _jsleep
ldx #2
; {
; {
; let the top part of the screen display normally.
; garbage begins to display on gr.0 line 8 (the one above the tops
; of the top row of lorchas).
@wait4scanline:
lda VCOUNT
cmp #(4+8)*4
bne @wait4scanline
; }
; {
; store random stuff into the players/missiles
@randpm:
sta WSYNC
lda RANDOM
sta GRAFP0
lda RANDOM
sta GRAFP1
lda RANDOM
sta GRAFP2
lda RANDOM
sta GRAFP3
lda RANDOM
sta GRAFM
lda VCOUNT
cmp #(4+23)*4
bne @randpm ; stop garbage 2 lines after the bottom row of lorchas
; }
; clear P/M for rest of frame
lda #0
sta GRAFP0
sta GRAFP1
sta GRAFP2
sta GRAFP3
sta GRAFM
lda RTCLOK+2
; {
; wait for start of next TV frame.
@wait4frame:
cmp RTCLOK+2
beq @wait4frame
; }
dex
bne @wait4scanline
; }
dec static_loop_count
bne @static_loop
; }
ldx #0 ; jsleep(10)
lda #$0a
jsr _jsleep
dey
bne @explosion_loop ; we're done if Y==0
; }
rts
; }
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