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dos33fsprogs/ootw/alien.s

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; draw/move the bad guy aliens
alien_state:
alien0:
alien0_out: .byte 0
alien0_x: .byte 0
alien0_y: .byte 0
alien0_state: .byte 0
alien0_gait: .byte 0
alien0_direction: .byte 0
alien0_gun: .byte 0
alien1:
alien1_out: .byte 0
alien1_x: .byte 0
alien1_y: .byte 0
alien1_state: .byte 0
alien1_gait: .byte 0
alien1_direction: .byte 0
alien1_gun: .byte 0
ALIEN_OUT = 0
ALIEN_X = 1
ALIEN_Y = 2
ALIEN_STATE = 3
ALIEN_GAIT = 4
ALIEN_DIRECTION = 5
ALIEN_GUN = 6
A_STANDING = 0
A_WALKING = 1
A_RUNNING = 2
A_CROUCHING = 3
A_TURNING = 4
A_YELLING = 5
A_SHOOTING_UP = 6
;=======================================
; Move alien based on current state
;
move_alien:
; FIXME: loop through all alieans
ldx #0
lda alien_state+ALIEN_OUT,X
beq done_move_alien
lda alien_state+ALIEN_STATE,X
cmp #A_WALKING
beq move_alien_walking
cmp #A_RUNNING
beq move_alien_running
cmp #A_YELLING
beq move_alien_yelling
cmp #A_SHOOTING_UP
beq move_alien_yelling
done_move_alien:
rts
;======================
; yelling
move_alien_yelling:
inc alien_state+ALIEN_GAIT,X ; cycle through animation
rts
;======================
; walking
move_alien_walking:
inc alien_state+ALIEN_GAIT,X ; cycle through animation
lda alien_state+ALIEN_GAIT,X
and #$f
cmp #$8 ; only walk roughly 1/8 of time
bne alien_no_move_walk
lda alien_state+ALIEN_DIRECTION,X
beq a_walk_left
inc alien_state+ALIEN_X,X ; walk right
rts
a_walk_left:
dec alien_state+ALIEN_X,X ; walk left
alien_no_move_walk:
rts
;======================
; running
move_alien_running:
inc alien_state+ALIEN_GAIT,X ; cycle through animation
lda alien_state+ALIEN_GAIT,X
and #$3
cmp #$2 ; only run roughly 1/4 of time
bne alien_no_move_run
lda alien_state+ALIEN_DIRECTION,X
beq a_run_left
inc alien_state+ALIEN_X,X ; run right
rts
a_run_left:
dec alien_state+ALIEN_X,X ; run left
alien_no_move_run:
rts
;======================
; standing
move_alien_standing:
astate_table_lo:
.byte <alien_standing ; 00
.byte <alien_walking ; 01
.byte <alien_running ; 02
.byte <alien_crouching ; 03
.byte <alien_turning ; 04
.byte <alien_yelling ; 05
.byte <alien_shooting_up; 06
astate_table_hi:
.byte >alien_standing ; 00
.byte >alien_walking ; 01
.byte >alien_running ; 02
.byte >alien_crouching ; 03
.byte >alien_turning ; 04
.byte >alien_yelling ; 05
.byte >alien_shooting_up; 06
; Urgh, make sure this doesn't end up at $FF or you hit the
; NMOS 6502 bug
.align 2
ajump:
.word $0000
.align 1
;======================================
; draw alien
;======================================
draw_alien:
; FIXME
ldx #0
lda alien_state+ALIEN_OUT,X
beq no_alien
lda alien_state+ALIEN_STATE,X
tay
lda astate_table_lo,y
sta ajump
lda astate_table_hi,y
sta ajump+1
jmp (ajump)
no_alien:
rts
;==================================
; STANDING
;==================================
alien_standing:
lda #<alien_stand
sta INL
lda #>alien_stand
sta INH
jmp finally_draw_alien
;===================================
; CROUCHING
;===================================
alien_crouching:
; FIXME: we have an animation?
lda #<alien_crouch2
sta INL
lda #>alien_crouch2
sta INH
jmp finally_draw_alien
;===============================
; Walking
;================================
alien_walking:
lda alien_state+ALIEN_GAIT,X
cmp #64
bcc alien_gait_fine ; blt
lda #0
sta alien_state+ALIEN_GAIT,X
alien_gait_fine:
lsr
lsr
and #$fe
tay
lda alien_state+ALIEN_GUN,X
beq alien_walk_nogun
alien_walk_gun:
lda alien_walk_gun_progression,Y
sta INL
lda alien_walk_gun_progression+1,Y
sta INH
jmp finally_draw_alien
alien_walk_nogun:
lda alien_walk_progression,Y
sta INL
lda alien_walk_progression+1,Y
sta INH
jmp finally_draw_alien
;===============================
; Running
;================================
alien_running:
lda alien_state+ALIEN_GAIT,X
cmp #32
bcc alien_run_gait_fine ; blt
lda #0
sta alien_state+ALIEN_GAIT,X
alien_run_gait_fine:
lsr
and #$fe
tay
lda alien_run_progression,Y
sta INL
lda alien_run_progression+1,Y
sta INH
jmp finally_draw_alien
;===============================
; Turning
;================================
alien_turning:
dec alien_state+ALIEN_GAIT,X
bpl alien_draw_turning
lda #0
sta alien_state+ALIEN_GAIT,X
; switch direction
lda alien_state+ALIEN_DIRECTION,X
eor #$1
sta alien_state+ALIEN_DIRECTION,X
lda #A_WALKING
sta alien_state+ALIEN_STATE,X
alien_draw_turning:
lda #<alien_turning_sprite
sta INL
lda #>alien_turning_sprite
sta INH
jmp finally_draw_alien
;===============================
; Yelling
;================================
alien_yelling:
lda alien_state+ALIEN_GAIT,X
; 00
; 01
; 10
; 11
and #$40
bne alien_yelling_no_waving
lda alien_state+ALIEN_GAIT,X
alien_yelling_no_waving:
and #$10
lsr
lsr
lsr
and #2
tay
lda alien_yell_progression,Y
sta INL
lda alien_yell_progression+1,Y
sta INH
jmp finally_draw_alien
;===============================
; Shooting Upward
;================================
alien_shooting_up:
lda alien_state+ALIEN_GAIT,X
and #$30
; 000 000
; 010 000
; 100 000
; 110 000
lsr
lsr
lsr
and #6
tay
lda alien_shoot_up_progression,Y
sta INL
lda alien_shoot_up_progression+1,Y
sta INH
cpy #0
lda alien_state+ALIEN_GAIT,X
; and #$ff
bne finally_draw_alien
lda #32
sta SHOOTING_BOTTOM
lda #28
sta SHOOTING_TOP
inc LITTLEGUY_OUT
; bne finally_draw_alien ; bra
;=============================
; Actually Draw Alien
;=============================
finally_draw_alien:
lda alien_state+ALIEN_X,X
sta XPOS
lda alien_state+ALIEN_Y,X
sta YPOS
lda alien_state+ALIEN_DIRECTION,X
bne alien_facing_right
alien_facing_left:
jmp put_sprite_crop
alien_facing_right:
jmp put_sprite_flipped_crop
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