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Balloon Fight (NES)/ROM map: Difference between revisions
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(begin rom map) |
(Added rommap template) |
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{{rommap|game=Balloon Fight}} | |||
== NMI == | == NMI == | ||
| Line 87: | Line 87: | ||
[$F0] = [$F1] = [$F2] = [$F3] = 0 | [$F0] = [$F1] = [$F2] = [$F3] = 0 | ||
return | return | ||
</pre> | </pre> | ||
Revision as of 22:16, 3 September 2011
The following article is a ROM map for Balloon Fight (NES).
NMI
The NMI handler runs every vertical blank in response to NMI. The pseudocode looks like this:
nmi = $C08A
push a, x, y
OAMADDR = 0
OAM_DMA = >OAM
if [$52] != [$53]:
call $C172
call updateStars
call updateStatusBar
retraces += 1
PPUADDR = $2000
PPUSCROLL = (0, 0)
call $FFF7
vblanked = $01
if [$16] != 0:
spinwait for vblank on PPUSTATUS=0 -- Nesticle code!
x = 4
y = $C6
spinwait x*1284+y*5-1 cycles
PPUCTRL = [$18] | [$00]
PPUSCROLL = ([$17], 0)
pull y, x, a
return
updateStatusBar = $D78E
y = [$46] - 1
if y != 0:
if y < 128:
tailcall $D7FB
return
PPUADDR = $2043
to PPUDATA write:
$8E, [$07] through [$03], $00, $24, 24,
$8C, $8D, [$11] through [$0D], $00, $24, 24
if [$16] != 0:
tailcall writeRank
if [$40] != 0:
to PPUDATA write:
$8F, [$0C] through [$0A], 0
[$46] -= 1
return
updateLives = $D7FB
writeGameOver = $D831
writeRank:
to PPUDATA write $F7, $F8, $F9, $FA, $FB, [$4A], [$49]
-- this text is "RANK-"
[$46] -= 1
return
updateStars = $D603
if [$4C] == 0:
return
[$4C] -= 1
[$4F] = X = ([$4F] + 2) & $3F
call writeOneStar
PPUADDR = ([$51], [$50])
a = PPUDATA
a = PPUDATA
for y in 3 to 0:
if a == $D642[y]:
tailcall $D631
return
writeOneStar:
PPUADDR = ([$51], [$50])
PPUDATA = $D643[y]
return
$FFF7:
tailcall $F758
$F758:
JOY2 = $C0
call $FB25
call $F90A
call $FA38
call $FAAC
call $F824
[$06E9] = [$F1]
[$F0] = [$F1] = [$F2] = [$F3] = 0
return
Physics
Code to handle physics starts at $EB84
; these two update the X and Y coordinates by adding the velocity to the position. updateActorX = $EB84 updateActorY = $EB96 ; these two call $F0AA before and after calling updateActorX, updateActorY ; the function of $F0AA is still not known updateActorXWithF0AA = $EBA8 updateActorYWithF0AA = $EBB1