diff options
Diffstat (limited to 'src/driver.s')
| -rw-r--r-- | src/driver.s | 162 |
1 files changed, 160 insertions, 2 deletions
diff --git a/src/driver.s b/src/driver.s index 4c2220f..c428475 100644 --- a/src/driver.s +++ b/src/driver.s @@ -18,7 +18,13 @@ PAUSE_TIMER_VALUE = (HZ / 3) zp_pause_timer = $32 - ;; Switch from the title screen to the main street. Note that this function + ;; Number of sprites available for sprite cycling. + SPRITE_CYCLING_BYTES = (64 - Player::PLAYER_SPRITES_COUNT) * 4 + + ;; TODO + zp_next_bullet_cycle = $33 + + ;; Switch from the title screen to the main screen. Note that this function ;; is to be called with the PPU disabled. If that's not the case, then it ;; will set the proper values to disable it on the next `nmi` call and set ;; the `title over` flag. With that, call again this function so the @@ -80,11 +86,15 @@ @load_player: jsr Player::init + jsr Bullets::init ;; Initialize pause timer. lda #0 sta zp_pause_timer + ;; Initialize variables for sprite cycling. + sta zp_next_bullet_cycle + @game: ;; Check if the player is toggling the `pause` state. lda #(Joypad::BUTTON_START | Joypad::BUTTON_SELECT) @@ -131,8 +141,156 @@ beq @do_update rts + ;; This is the actual meat of the main game, which updates the state of + ;; the player, bullets, enemies, etc. @do_update: - JAL Player::update + jsr Player::update + jsr Bullets::update + JAL sprite_cycling + ;; TODO: fall through? + .endproc + + .proc sprite_cycling + ;; The 'y' register will contain the index on OAM of the sprite to be + ;; allocated. + ldy #(Player::PLAYER_SPRITES_COUNT * 4) + + ;; The 'x' register will index from the different sprite pools. + ldx zp_next_bullet_cycle + lda Bullets::zp_bullets_pool_base, x + + ;; Is this a valid bullet? + cmp #$FF + beq @after_first_bullet + + ;; It is a valid bullet! Set it now. + lda Bullets::zp_bullets_pool_base + 1, x + sta $200, y + iny + + ;; The tile selection depends on how many moves the bullet has done. + lda Bullets::zp_bullets_pool_base, x + and #%01111111 + cmp #Bullets::BULLET_LAST_TRANSITION + bcs @last_bullet_tile + cmp #Bullets::BULLET_FIRST_TRANSITION + bcs @mid_bullet_tile + lda #$0E + bne @set_bullet_tile + @mid_bullet_tile: + lda #$0F + bne @set_bullet_tile + @last_bullet_tile: + lda #$1E + @set_bullet_tile: + sta $200, y + + iny + lda #0 + sta $200, y + iny + lda Bullets::zp_bullets_pool_base + 2, x + sta $200, y + iny + + @after_first_bullet: + ;; Save the index that was considered for the first bullet. + stx Globals::zp_tmp0 + + ;; Increase the index for the bullets cycling. If wrapping is detected, + ;; then it resets this value back to zero. + inx + inx + inx + cpx #Bullets::BULLETS_POOL_CAPACITY_BYTES + bne @set_next_bullets_cycle + ldx #0 + @set_next_bullets_cycle: + stx zp_next_bullet_cycle + + ;; TODO: ensure 1 enemy + iny + iny + iny + iny + + ;; TODO: ensure 1 item + iny + iny + iny + iny + + ;; TODO: rest of bullets + ldx #0 + @rest_o_bullets: + cpx #Bullets::BULLETS_POOL_CAPACITY_BYTES + beq @rest_o_enemies + cpx Globals::zp_tmp0 + bne @do_bullet + inx + inx + inx + cpx #Bullets::BULLETS_POOL_CAPACITY_BYTES + beq @rest_o_enemies + @do_bullet: + lda Bullets::zp_bullets_pool_base, x + cmp #$FF + beq @next_bullet + + lda Bullets::zp_bullets_pool_base + 1, x + sta $200, y + iny + + ;; The tile selection depends on how many moves the bullet has done. + lda Bullets::zp_bullets_pool_base, x + and #%01111111 + cmp #Bullets::BULLET_LAST_TRANSITION + bcs @other_last_bullet_tile + cmp #Bullets::BULLET_FIRST_TRANSITION + bcs @other_mid_bullet_tile + lda #$0E + bne @other_set_bullet_tile + @other_mid_bullet_tile: + lda #$0F + bne @other_set_bullet_tile + @other_last_bullet_tile: + lda #$1E + @other_set_bullet_tile: + sta $200, y + + iny + lda #0 + sta $200, y + iny + lda Bullets::zp_bullets_pool_base + 2, x + sta $200, y + iny + + @next_bullet: + inx + inx + inx + jmp @rest_o_bullets + + @rest_o_enemies: + ;; TODO: rest of enemies + ;; TODO: rest of items + + ;; We are done with all the sprites we wanted to allocat. Now let's + ;; clear out the rest of the slots just in case there was some leftover + ;; from a past sprite. + lda #$EF + @check_cycle_end: + cpy #SPRITE_CYCLING_BYTES + bne @reset_sprite + rts + @reset_sprite: + sta $200, y + iny + iny + iny + iny + jmp @check_cycle_end ;TODO: maybe just bne? .endproc .ifdef PAL |