mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-12-27 02:31:00 +00:00
270 lines
4.2 KiB
ArmAsm
270 lines
4.2 KiB
ArmAsm
; Display falling snow
|
|
|
|
; by deater (Vince Weaver) <vince@deater.net>
|
|
|
|
; Zero Page
|
|
CH = $24
|
|
CV = $25
|
|
GBASL = $26
|
|
GBASH = $27
|
|
BASL = $28
|
|
BASH = $29
|
|
|
|
SEEDL = $4E
|
|
SEEDH = $4F
|
|
|
|
HGR_COLOR = $E4
|
|
SNOWX = $F0
|
|
TEMPY = $F1
|
|
|
|
HGR = $F3E2
|
|
|
|
|
|
NUMFLAKES = 10
|
|
|
|
|
|
.include "hardware.inc"
|
|
|
|
|
|
;==================================
|
|
;==================================
|
|
|
|
jsr HGR
|
|
bit FULLGR
|
|
|
|
|
|
;==================================
|
|
; init snow
|
|
;==================================
|
|
|
|
ldx #NUMFLAKES-1
|
|
snow_init_loop:
|
|
|
|
jsr random16
|
|
|
|
lda SEEDL
|
|
and #$3f
|
|
sta snow_x,X
|
|
|
|
lda SEEDH
|
|
and #$7f
|
|
sta snow_y,X
|
|
|
|
dex
|
|
bpl snow_init_loop
|
|
|
|
|
|
display_loop:
|
|
|
|
; 0 4 8 c 10 14 18 1c
|
|
; 0 1 2 3 4 5 6 7
|
|
|
|
;=========================
|
|
; erase old snow
|
|
;=========================
|
|
; 2 + (35+29+7)*NUMFLAKES - 1
|
|
; 1 +71*NUMFLAKES = 711
|
|
|
|
ldx #0 ; 2
|
|
erase_loop:
|
|
lda snow_y,X ; get Y ; 4+
|
|
lsr ; 2
|
|
lsr ; 2
|
|
lsr ; divide by 8 ; 2
|
|
sta TEMPY ; 3
|
|
lda snow_x,X ; 4+
|
|
tay ; 2
|
|
lda div_7_q,Y ; 4+
|
|
ldy TEMPY ; 3
|
|
clc ; 2
|
|
adc hgr_offsets_l,Y ; 4+
|
|
sta GBASL ; 3
|
|
adc #30
|
|
sta BASL
|
|
;=============
|
|
; 35
|
|
|
|
lda snow_y,X ; 4+
|
|
asl ; 2
|
|
asl ; 2
|
|
and #$1f ; 2
|
|
clc ; 2
|
|
adc hgr_offsets_h,Y ; 4
|
|
sta GBASH ; 3
|
|
sta BASH
|
|
lda #0 ; 2
|
|
tay ; 2
|
|
sta (GBASL),Y ; 6
|
|
sta (BASL),Y
|
|
|
|
;============
|
|
; 29
|
|
|
|
inx ; 2
|
|
cpx #NUMFLAKES ; 2
|
|
bne erase_loop ; 3
|
|
;============
|
|
; 7
|
|
|
|
; -1
|
|
|
|
;==========================
|
|
; move snow
|
|
;
|
|
; 2 +
|
|
|
|
ldx #0 ; 2
|
|
move_snow:
|
|
lda snow_y,X ; 4+
|
|
cmp #160 ; 2
|
|
bne just_inc ; 3
|
|
; -1
|
|
|
|
; out of bounds, get new
|
|
lda #30 ; 2
|
|
sta snow_y,X ; 5
|
|
lda SEEDH
|
|
and #$3f
|
|
sta snow_x,X
|
|
jmp done_inc ; 3
|
|
|
|
|
|
just_inc:
|
|
|
|
jsr random16 ; 6+42
|
|
lda SEEDL ; 3
|
|
and #$f ; 2
|
|
|
|
beq snow_left ; 3
|
|
; -1
|
|
cmp #$1 ; 2
|
|
beq snow_right ; 3
|
|
; -1
|
|
|
|
inc snow_y,X ; 6
|
|
|
|
jmp snow_no ; 3
|
|
|
|
snow_right:
|
|
inc snow_x,X ; 6
|
|
jmp snow_no ; 3
|
|
|
|
snow_left:
|
|
dec snow_x,X ; 6
|
|
snow_no:
|
|
lda snow_x,X
|
|
and #$3f
|
|
sta snow_x,X
|
|
|
|
done_inc:
|
|
inx ; 2
|
|
cpx #NUMFLAKES ; 2
|
|
bne move_snow ; 3
|
|
; -1
|
|
|
|
;=========================
|
|
; draw new snow
|
|
;=========================
|
|
; 2+ (35+22+19+7)*NUMFLAKES -1
|
|
; 1+83*NUMFLAKES = 831
|
|
|
|
ldx #0 ; 2
|
|
draw_loop:
|
|
lda snow_y,X ; 4+
|
|
lsr ; 2
|
|
lsr ; 2
|
|
lsr ; 2
|
|
sta TEMPY ; 3
|
|
lda snow_x,X ; 4+
|
|
tay ; 2
|
|
lda div_7_q,Y ; 4+
|
|
ldy TEMPY ; 3
|
|
clc ; 2
|
|
adc hgr_offsets_l,Y ; 4+
|
|
sta GBASL ; 3
|
|
adc #32
|
|
sta BASL
|
|
;===========
|
|
; 35
|
|
|
|
lda snow_y,X ; 4+
|
|
asl ; 2
|
|
asl ; 2
|
|
and #$1f ; 2
|
|
clc ; 2
|
|
adc hgr_offsets_h,Y ; 4+
|
|
sta GBASH ; 3
|
|
sta BASH
|
|
;=============
|
|
; 19
|
|
|
|
ldy snow_x,X ; 4+
|
|
lda div_7_r,Y ; 4+
|
|
tay ; 2
|
|
lda pixel_lookup,Y ; 4+
|
|
|
|
ldy #0 ; 2
|
|
sta (GBASL),Y ; 6
|
|
sta (BASL),Y
|
|
;=============
|
|
; 22
|
|
|
|
inx ; 2
|
|
cpx #NUMFLAKES ; 2
|
|
bne draw_loop ; 3
|
|
;=============
|
|
; 7
|
|
|
|
; -1
|
|
lda #100
|
|
jsr WAIT
|
|
|
|
jmp display_loop ; 3
|
|
|
|
|
|
snow_x:
|
|
.byte 0,0,0,0,0,0,0,0,0,0
|
|
|
|
snow_y:
|
|
.byte 0,0,0,0,0,0,0,0,0,0
|
|
|
|
hgr_offsets_h:
|
|
.byte >$2000,>$2080,>$2100,>$2180,>$2200,>$2280,>$2300,>$2380
|
|
.byte >$2028,>$20A8,>$2128,>$21A8,>$2228,>$22A8,>$2328,>$23A8
|
|
.byte >$2050,>$20D0,>$2150,>$21D0,>$2250,>$22D0,>$2350,>$23D0
|
|
|
|
hgr_offsets_l:
|
|
.byte <$2000,<$2080,<$2100,<$2180,<$2200,<$2280,<$2300,<$2380
|
|
.byte <$2028,<$20A8,<$2128,<$21A8,<$2228,<$22A8,<$2328,<$23A8
|
|
.byte <$2050,<$20D0,<$2150,<$21D0,<$2250,<$22D0,<$2350,<$23D0
|
|
|
|
|
|
div_7_q:
|
|
.byte 0,0,0,0,0,0,0 ; 0..6
|
|
.byte 1,1,1,1,1,1,1 ; 7..13
|
|
.byte 2,2,2,2,2,2,2 ; 14..20
|
|
.byte 3,3,3,3,3,3,3 ; 21..27
|
|
.byte 4,4,4,4,4,4,4 ; 28..34
|
|
.byte 5,5,5,5,5,5,5 ; 35..41
|
|
.byte 6,6,6,6,6,6,6 ; 42..48
|
|
.byte 7,7,7,7,7,7,7 ; 49..55
|
|
.byte 8,8,8,8,8,8,8 ; 56..62
|
|
.byte 9 ; 63
|
|
|
|
div_7_r:
|
|
.byte 0,1,2,3,4,5,6 ; 0..6
|
|
.byte 0,1,2,3,4,5,6 ; 7..13
|
|
.byte 0,1,2,3,4,5,6 ; 14..20
|
|
.byte 0,1,2,3,4,5,6 ; 21..27
|
|
.byte 0,1,2,3,4,5,6 ; 28..34
|
|
.byte 0,1,2,3,4,5,6 ; 35..41
|
|
.byte 0,1,2,3,4,5,6 ; 42..48
|
|
.byte 0,1,2,3,4,5,6 ; 49..55
|
|
.byte 0,1,2,3,4,5,6 ; 56..62
|
|
.byte 0 ; 63
|
|
|
|
pixel_lookup:
|
|
.byte $01,$02,$04,$08,$10,$20,$40
|
|
|
|
.include "random16.s"
|