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|
.segment "CODE"
.scope Over
;; Has the "Game over" screen been displayed yet?
zp_displayed = $10
;; Timer set whenever the "Game over" screen has been displayed. Whenever it
;; times out, then the player is redirected to the title screen.
zp_timer = $11
;; Amount of time the player has to wait for the title screen to appear
;; again.
TIMER_VALUE = HZ * 3
;; Initialize all variables for the "Game over" screens.
.proc init
lda #0
sta Over::zp_displayed
sta Over::zp_timer
rts
.endproc
;; Handle a "Game over" screen. It has two phases:
;; 1. Render a "Game over" message.
;; 2. Wait for a timer to time out.
;; It will set 1 to the 'a' register if the timer has run out, signaling
;; that the game can start over. Otherwise it sets 0 to the 'a' register.
.proc handle
ldy #0
;; Has the "Game over" screen been displayed? If not do it now.
lda Over::zp_displayed
bne @do_handle
jsr Over::render
jmp @end
@do_handle:
lda Over::zp_timer
bne @dec_timer
iny
beq @end
@dec_timer:
dec Over::zp_timer
@end:
tya
rts
.endproc
;; Render the "Game over" message to the screen. This is done in two
;; phases. We first ensure to disable the PPU, and in the second phase we do
;; the actual writing.
.proc render
;; Is PPU disabled? If it is then jump into rendering the screen
;; directly.
lda PPU::zp_mask
beq @do_render
;; Nope! Force the PPU to be disabled and quit.
lda Globals::zp_flags
ora #%01000000
sta Globals::zp_flags
lda #$00
sta PPU::zp_mask
rts
@do_render:
jsr Over::clear_out_screen
;; TODO: coin game over.
jsr Over::render_regular_game_over
;; Enable back the PPU (only background).
lda #%00001110
sta PPU::zp_mask
;; Update PPU registers.
lda #%01000000
ora Globals::zp_flags
sta Globals::zp_flags
;; Set the "Game over" message as displayed and fire up the timer.
lda #1
sta Over::zp_displayed
lda #Over::TIMER_VALUE
sta Over::zp_timer
rts
.endproc
;; Remove all platforms and the ground.
.proc clear_out_screen
;; Remove left platform.
bit PPU::m_status
ldx #$29
stx PPU::m_address
ldx #$83
stx PPU::m_address
lda #$00
sta PPU::m_data
sta PPU::m_data
sta PPU::m_data
sta PPU::m_data
sta PPU::m_data
sta PPU::m_data
sta PPU::m_data
;; Remove center platform.
bit PPU::m_status
ldx #$29
stx PPU::m_address
ldx #$EF
stx PPU::m_address
sta PPU::m_data
sta PPU::m_data
sta PPU::m_data
sta PPU::m_data
sta PPU::m_data
;; Remove right platform.
bit PPU::m_status
ldx #$29
stx PPU::m_address
ldx #$38
stx PPU::m_address
sta PPU::m_data
sta PPU::m_data
sta PPU::m_data
sta PPU::m_data
sta PPU::m_data
sta PPU::m_data
sta PPU::m_data
;; Ground
bit PPU::m_status
ldx #$2B
stx PPU::m_address
ldx #$20
stx PPU::m_address
ldx #$20
@clear_ground_loop:
sta PPU::m_data
dex
bne @clear_ground_loop
;; The low part of the rocket.
bit PPU::m_status
ldx #$2B
stx PPU::m_address
ldx #$15
stx PPU::m_address
sta PPU::m_data
sta PPU::m_data
;; High part of the rocket.
bit PPU::m_status
ldy #$2A
sty PPU::m_address
ldx #$75
stx PPU::m_address
sta PPU::m_data
sta PPU::m_data
bit PPU::m_status
sty PPU::m_address
ldx #$95
stx PPU::m_address
sta PPU::m_data
sta PPU::m_data
bit PPU::m_status
sty PPU::m_address
ldx #$B5
stx PPU::m_address
sta PPU::m_data
sta PPU::m_data
;; Middle part of the rocket.
bit PPU::m_status
sty PPU::m_address
ldx #$D5
stx PPU::m_address
sta PPU::m_data
sta PPU::m_data
bit PPU::m_status
sty PPU::m_address
ldx #$F5
stx PPU::m_address
sta PPU::m_data
sta PPU::m_data
rts
.endproc
;; Render the regular "Game over" screen.
.proc render_regular_game_over
;; Set the position.
bit PPU::m_status
ldx #$29
stx PPU::m_address
ldx #$6C
stx PPU::m_address
;; And just iterate over the "message" until we reach the end of string
;; $FF character.
ldx #0
@message_loop:
lda message, x
cmp #$FF
beq @out
sta PPU::m_data
inx
bne @message_loop
@out:
;; Reset attributes for the end of the message.
bit PPU::m_status
ldx #$2B
stx PPU::m_address
ldx #$D5
stx PPU::m_address
lda #0
sta PPU::m_data
sta PPU::m_data
sta PPU::m_data
rts
message:
;; "GAME "
.byte $21, $1B, $27, $1F, $00
;; "OVER"
.byte $29, $30, $1F, $2C, $FF
.endproc
.endscope
|
