diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/items.s | 31 |
1 files changed, 29 insertions, 2 deletions
diff --git a/src/items.s b/src/items.s index c7d0d05..731756d 100644 --- a/src/items.s +++ b/src/items.s @@ -111,6 +111,12 @@ ;; NOTE: 16-bit integer in little-endian format. zp_timer = $CC ; asan:reserve $02 + ;; Fuel tanks go into a different timer, which should be way snappier than + ;; the default 'Items::zp_timer'. This is because in the original whenever a + ;; fuel tank was needed, it felt down almost right away. + FUEL_TIMER = HZ + zp_fuel_timer = $CE + ;; Initialize variables just before switching to the current level. ;; ;; NOTE: variables initialized here are supposed to live after @@ -213,6 +219,10 @@ lda #ITEM_TIMER_HI sta Items::zp_timer + 1 + ;; Initialize the fuel timer. + lda #Items::FUEL_TIMER + sta Items::zp_fuel_timer + rts .endproc @@ -512,13 +522,16 @@ ;; Now we unset the 'S' bit, which is unconditionally true regardless of ;; the collection state. That being said, if we still need to collect ;; more fuel tanks (the rocket has all its parts and we have not filled - ;; it with all tanks), then we set the 'N' bit. + ;; it with all tanks), then we set the 'N' bit (and we reset the fuel + ;; timer). lda Items::zp_state ldy Items::zp_collected cpy #3 bcc @set_new_state cpy #9 beq @set_new_state + ldy #Items::FUEL_TIMER + sty Items::zp_fuel_timer ora #$40 @set_new_state: and #%11011111 @@ -658,11 +671,23 @@ sbc #0 sta Items::zp_timer + 1 + ;; If the 'N' bit is set, then we only care about the snappier + ;; 'Items::zp_fuel_timer' value. If that timer has run out, ignore the + ;; default one and jump right into initializing a new item (which will + ;; be a fuel tank, as guaranteed by init_item_x()). + lda Items::zp_state + and #$40 + beq @check_timer + dec Items::zp_fuel_timer + beq @new_item_x + + @check_timer: ;; If it times out, initialize a new item at this position. lda Items::zp_timer bne @end lda Items::zp_timer + 1 bne @end + @new_item_x: stx Items::zp_pool_index JAL init_item_x @@ -670,7 +695,9 @@ rts .endproc - ;; Initialize an item from the pool as indexed by the 'x' register. + ;; Initialize an item from the pool as indexed by the 'x' register. The item + ;; will be randomized unless the 'N' bit is set from 'Items::zp_state', in + ;; which case a fuel tank will just be delivered. ;; ;; NOTE: the 'x' register is modified, but the 'y' register is not touched. .proc init_item_x |