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Added nes_bank1.l65 sample. 

Allowed more customization for CHR rom layout.
This commit is contained in:
g012 2017-12-28 21:16:45 +01:00
parent 808bf10b26
commit d539f9c194
3 changed files with 238 additions and 99 deletions
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1
.travis.yml
View File

@ -18,6 +18,7 @@ script:
- ../l65 vcs_mcart.l65
- ../l65 vcs_spr48.l65
- ../l65 nes_hello.l65
- ../l65 nes_bank1.l65
- cd ..
- cp l65 l65-$TRAVIS_TAG-$TRAVIS_OS_NAME
deploy:

241
nes.l65
View File

@ -61,12 +61,12 @@ end
-- add some symbol file formats for NES debuggers
cpu.getsym_as.mesen = function() -- .mlb
local ins,fmt = table.insert,string.format
local s = getsym(function(a,l)
local s = getsym(function(a,l,lorg)
if a >= 0x10000 then return end
local prefix = {}
if a < 0x2000 then prefix[1]='R'
elseif a >= 0x6000 and a < 0x8000 then prefix[1]='S' prefix[2]='W' a=a-0x6000
elseif a >= 0x8000 then prefix[1]='P' a=a-0x8000
elseif a >= 0x8000 then prefix[1]='P' a=(symbolsorg[lorg] or a)-0x8000
else prefix[1]='G' end
local s = {}
for _,p in ipairs(prefix) do ins(s, fmt("%s:%04x:%s", p, a, l)) end
@ -77,11 +77,11 @@ end
cpu.getsym_as.fceux = function(filename) -- .nl, multiple files
local ins,fmt = table.insert,string.format
local ram,rom = {},{}
local s = getsym(function(a,l)
local s = getsym(function(a,l,lorg)
local s = fmt("$%04x#%s#", a, l)
if a < 0x8000 then ins(ram, s)
elseif a < 0x10000 then
local a_org = symbolsorg[l] or a
local a_org = symbolsorg[lorg] or a
local romstart = locations[2].start -- header location should always be defined first, skip it
if a_org >= romstart then
local bank = math.floor((a_org - romstart) / 0x4000)
@ -277,10 +277,36 @@ end
local n0ne = function(x) return not x or x == 0 end
local val0 = function(x) return x and x or 0 end
--[[ For all mappers, where relevant:
prg rom banks:
prgroms are numbered from last (0) to first (#-1), so that adding more does not change
prgrom0, which must contain the reset vector (main). The switchprgrom* functions expect
a bank index according to this reversed numbering (0 is last physical bank in ROM).
t.prgmap is an optional function taking a prgrom bank index and returning its rorg value.
Default is to map banks in sequence according to their size, eg.:
* for sizes 32kB: always 0x8000.
* for sizes 16kB+16kB: repeat sequence 0x8000, 0xa000.
* for sizes 16kB+8kB+8kB: repeat sequence 0x8000, 0xc000, 0xe000.
* for sizes 8kB+8kB+8kB+8kB: repeat sequence 0x8000, 0xa000, 0xc000, 0xe000.
If last bank is fixed, it is not part of the sequence and its mapping value is skipped:
* for sizes 8kB+8kB+ last fixed 16kB: repeat sequence 0x8000, 0xa000, set last bank to 0xc000.
chr rom banks:
chrroms are numbered in physical ROM address order, unlike prgroms.
Banks are created with the smallest switchable size, maximum being 4kB by default.
t.chrmap is an optional function taking a chrrom bank index and returning its offset in
ROM from the beginning of the first chrrom, its size (defaults to everything remaining),
and its relocation origin (defaults to 0).
So if a mapper allows switching chrroms in any of 1-1-1-1-1-1-1-1kB / 2-2-2-2kB, etc.,
the default is to create only 1kB chrroms. Conversely, with a mapper switching only in 8kB
slices, 4kB chrrom are created, not 8kB (but you can specify any size using t.chrmap).
]]
--[[
https://wiki.nesdev.com/w/index.php/NROM
4kB chrroms are created, unless t.onechrrom is set, in which case only one big chrrom
location is created instead.
]]
mappers.NROM = function(t)
if not t then t = {} end
@ -296,15 +322,15 @@ mappers.NROM = function(t)
prgrom = prgrom0
section{"vectors", org=0xfffa} dc.w nmi, main, irq
if (t.chrsize > 0) then
if t.onechrrom then
chrrom0 = location{0x10000, 0x10000 + 0x1fff, name='chrrom'}
else
for ci=0,1 do
local o = 0x10000 + ci*0x1000
_ENV['chrrom'..ci] = location{o, o+0xfff, name='chrrom'..ci}
end
end
chrrom = chrrom0
local chrmap = t.chrmap or function(ci) return ci*0x1000, 0x1000, (ci&1)*0x1000 end
repeat
local off, sz, rorg = chrmap(ci)
sz = sz or t.chrsize - off
local o = off + 0x10000
_ENV['chrrom'..ci] = location{o, o+sz-1, rorg=rorg or 0, name='chrrom'..ci}
ci = ci+1
until off + sz >= t.chrsize
chrrom = chrrom0
end
end
mappers[0] = mappers.NROM
@ -312,8 +338,6 @@ mappers[0] = mappers.NROM
--[[
https://wiki.nesdev.com/w/index.php/UxROM
Has bus conflicts.
4kB chrroms are created, unless t.onechrrom is set, in which case only one big chrrom
location is created instead.
]]
mappers.UxROM = function(t)
if not t then t = {} end
@ -323,6 +347,8 @@ mappers.UxROM = function(t)
if not t.chrsize then t.chrsize = 8192 end
assert(t.chrsize == 0x2000, "chrsize must be 8kB")
assert(not t.mirror or ({ h=1, v=1 })[t.mirror:lower()], "only H and V mirroring are supported")
hdrrom = location{0x7ff0, 0x7fff, name='header'}
header(t)
local bc = t.prgsize//0x4000
for bi=0,bc-2 do
local o,ix = 0x8000 + bi*0x4000, bc-1-bi
@ -333,20 +359,21 @@ mappers.UxROM = function(t)
prgrom = prgrom0
section{"vectors", org=prglast+0x3ffa} dc.w nmi, main, irq
@@bankbytes -- for handling bus conflicts
for i=0,bc-2 do byte(i) end
local chrstart = 0x8000 + bc*0x4000
if t.onechrrom then
chrrom0 = location{chrstart, chrstart + 0x1fff, name='chrrom'}
else
for ci=0,1 do
local o = chrstart + ci*0x1000
_ENV['chrrom'..ci] = location{o, o+0xfff, name='chrrom'..ci}
end
end
samepage for i=bc-1,0,-1 do byte(i) end end
local ci, chrstart = 0, 0x8000 + bc*0x4000
local chrmap = t.chrmap or function(ci) return ci*0x1000, 0x1000, (ci&1)*0x1000 end
repeat
local off, sz, rorg = chrmap(ci)
sz = sz or t.chrsize - off
local o = off + chrstart
_ENV['chrrom'..ci] = location{o, o+sz-1, rorg=rorg or 0, name='chrrom'..ci}
ci = ci+1
until off + sz >= t.chrsize
chrrom = chrrom0
function switchprgrom(bankix)
assert(bankix < bc-1)
lda #bankix tax sta bankbytes,x
if bankix then assert(bankix < bc-1) lda #bankix end
-- lda to reverse map [n..0] to [0..n]
tax lda bankbytes,x sta bankbytes,x
end
mappers.init = function()
switchprgrom(1)
@ -357,8 +384,6 @@ mappers[2] = mappers.UxROM
--[[
https://wiki.nesdev.com/w/index.php/CNROM
Has bus conflicts.
8kB chrroms are created, unless t.onechrrom is set, in which case only one big chrrom
location is created instead.
]]
mappers.CNROM = function(t)
if not t then t = {} end
@ -373,26 +398,32 @@ mappers.CNROM = function(t)
header(t)
prgrom = location{prgstart, 0xffff, name='prgrom'}
section{"vectors", org=0xfffa} dc.w nmi, main, irq
@@bankbytes -- for handling bus conflicts
@@bankbytes samepage -- for handling bus conflicts
dc.b 0x00, 0x01, 0x02, 0x03
dc.b 0x10, 0x11, 0x12, 0x13
dc.b 0x20, 0x21, 0x22, 0x23
dc.b 0x30, 0x31, 0x32, 0x33
local cc = t.chrsize//0x2000
if t.onechrrom then
chrrom0 = location{chrstart, chrstart + cc*0x2000 - 1, rorg=0, name='chrrom'}
else
for ci=0,cc-1 do
local o = chrstart + ci*0x2000
_ENV['chrrom'..ci] = location{o, o+0x2000-1, rorg=0, name='chrrom'..ci}
end
end
local ci, cc = 0, t.chrsize//0x2000
local chrmap = t.chrmap or function(ci) return ci*0x1000, 0x1000, (ci&1)*0x1000 end
repeat
local off, sz, rorg = chrmap(ci)
sz = sz or t.chrsize - off
local o = off + 0x10000
_ENV['chrrom'..ci] = location{o, o+sz-1, rorg=rorg or 0, name='chrrom'..ci}
ci = ci+1
until off + sz >= t.chrsize
chrrom = chrrom0
securitydiodes = 0 -- set to actual value, eg 0x20
function switchchrrom(bankix)
assert(bankix < cc)
assert(securitydiodes < 0x40)
ldx #bankix|securitydiodes>>2 lda #bankix|securitydiodes sta bankbytes,x
if bankix then
assert(bankix < cc)
ldx #bankix|securitydiodes>>2 lda #bankix|securitydiodes
else
ora #securitydiodes>>2 tax and #3 ora #securitydiodes
end
sta bankbytes,x
end
mappers.init = function()
switchchrrom(0)
@ -403,12 +434,6 @@ mappers[3] = mappers.CNROM
--[[
https://wiki.nesdev.com/w/index.php/GxROM
Has bus conflicts.
prgroms are numbered from last (0) to first (#-1), so that adding more does not change
prgrom0, which must contain the reset vector (main).
8kB chrroms are created, unless t.onechrrom is set, in which case only one big chrrom
location is created instead.
]]
mappers.GxROM = function(t)
if not t then t = {} end
@ -424,13 +449,14 @@ mappers.GxROM = function(t)
for bi=0,bc-1 do
local o,ix = 0x8000 + bi*0x8000, bc-1-bi
_ENV['prgrom'..ix] = location{o, o+0x7fff, rorg=0x8000, name='prgrom'..ix}
section("bankbytes"..ix) -- for handling bus conflicts
section{"vectors"..ix, org=o+0x8000-6} dc.w nmi, main, irq
section{"bankbytes"..ix, org=o+0x8000-6-16} samepage -- for handling bus conflicts
dc.b 0x00, 0x01, 0x02, 0x03
dc.b 0x10, 0x11, 0x12, 0x13
dc.b 0x20, 0x21, 0x22, 0x23
dc.b 0x30, 0x31, 0x32, 0x33
end
end
section{"vectors", org=0x8000+bc*0x8000-6} dc.w nmi, main, irq
prgrom = prgrom0
local cc = t.chrsize//0x2000
if t.onechrrom then
@ -441,17 +467,46 @@ mappers.GxROM = function(t)
_ENV['chrrom'..ci] = location{o, o+0x2000-1, rorg=0, name='chrrom'..ci}
end
end
local ci, chrstart = 0, 0x8000 + bc*0x8000
local chrmap = t.chrmap or function(ci) return ci*0x1000, 0x1000, (ci&1)*0x1000 end
repeat
local off, sz, rorg = chrmap(ci)
sz = sz or t.chrsize - off
local o = off + chrstart
_ENV['chrrom'..ci] = location{o, o+sz-1, rorg=rorg or 0, name='chrrom'..ci}
ci = ci+1
until off + sz >= t.chrsize
chrrom = chrrom0
-- RAM address of bank register copy, to switch using A instead of immediate
bankregister_shadow = -1
-- if bankregister_shadow is negative, only immediate bankswitching is available
bankregister = 0
-- otherwise, just set the value directly: xxPPxxCC in A, xxxxPPCC in X with sta bankbytes0,x
function switchprgrom(bankix)
assert(bankix < bc)
bankregister = (bankregister & ~0x30) | (bankix << 4)
ldx #bankregister&3|bankregister>>2 lda #bankregister sta bankbytes0,x
if bankix then
assert(bankix < bc)
bankregister = (bankregister & ~0x30) | (bankix << 4)
ldx #bankregister&3|bankregister>>2 lda #bankregister sta bankbytes0,x
else
assert(bankregister_shadow >= 0, "no RAM slot assigned to bankregister_shadow")
tay lda bankregister_shadow and #3 sta bankregister_shadow
tya asl asl ora bankregister_shadow tax
and #0xc asl asl ora bankregister_shadow sta bankregister_shadow
sta bankbytes0,x
end
end
function switchchrrom(bankix)
assert(bankix < cc)
bankregister = (bankregister & ~3) | bankix
ldx #bankregister&3|bankregister>>2 lda #bankregister sta bankbytes0,x
if bankix then
assert(bankix < cc)
bankregister = (bankregister & ~3) | bankix
ldx #bankregister&3|bankregister>>2 lda #bankregister sta bankbytes0,x
else
assert(bankregister_shadow >= 0, "no RAM slot assigned to bankregister_shadow")
tay lda bankregister_shadow lsr lsr sta bankregister_shadow
tya ora bankregister_shadow tax and #0xc
asl asl sta bankregister_shadow tya ora bankregister_shadow sta bankregister_shadow
sta bankbytes0,x
end
end
mappers.init = function()
switchchrrom(0)
@ -462,27 +517,24 @@ mappers[66] = mappers.GxROM
--[[
https://wiki.nesdev.com/w/index.php/MMC1
prgroms are numbered from last (0) to first (#-1), so that adding more does not change
prgrom0, which must contain the reset vector (main).
t.prgmap is an optional function taking a prgrom bank index and returning its rorg value.
Default is to create 16kB banks if prgswitchmode is not all, 32kB otherwise, and rorg them
accordingly.
Same goes for chrrom sizes.
If t.onechrrom is set, only one big chrrom location is created instead.
t.prgswitchmode:
'first' makes 0x8000-0xbfff switchable (default)
'last' makes 0xc000-0xffff switchable
'all' makes 0x8000-0xffff switchable
t.chrswitchmode:
'all' switches whole 8kB at a time (default)
'half' switches 2 separate 4kB banks
'all' switches whole 8kB at a time
'half' switches 2 separate 4kB banks (default)
]]
mappers.MMC1 = function(t)
if not t then t = {} end
t.mapperid = 1
if not t.prgswitchmode then t.prgswitchmode = 'first' end
if not t.chrswitchmode then t.chrswitchmode = 'all' end
if not t.chrswitchmode then t.chrswitchmode = 'half' end
if not t.wramsize then t.wramsize = 0 end
if not t.bramsize and t.wramsize == 0 then t.bramsize = 8192 end
local prgram = t.bramsize + t.wramsize
@ -502,18 +554,17 @@ mappers.MMC1 = function(t)
end
section{"vectors", org=0x8000+bc*bsz-6} dc.w nmi, main, irq
prgrom = prgrom0
local chrstart = 0x8000 + bc*bsz
local ci, chrstart = 0, 0x8000 + bc*bsz
local csz = t.chrswitchmode=='all' and 0x2000 or 0x1000
local cc = t.chrsize//csz
local chrmap = t.chrmap or function(ci, cc) if csz==0x2000 then return 0 else return (ci&1)*csz end end
if t.onechrrom then
chrrom0 = location{chrstart, chrstart + cc*csz - 1, rorg=0, name='chrrom'}
else
for ci=0,cc-1 do
local o = chrstart + ci*csz
_ENV['chrrom'..ci] = location{o, o+csz-1, rorg=chrmap(ci,cc), name='chrrom'..ci}
end
end
local chrmap = t.chrmap or function(ci) return ci*0x1000, 0x1000, (ci&1)*0x1000 end
repeat
local off, sz, rorg = chrmap(ci)
sz = sz or t.chrsize - off
local o = off + chrstart
_ENV['chrrom'..ci] = location{o, o+sz-1, rorg=rorg or 0, name='chrrom'..ci}
ci = ci+1
until off + sz >= t.chrsize
chrrom = chrrom0
local prgswitchmodemap = { all=0, first=3<<2, last=2<<2 }
@ -569,11 +620,8 @@ mappers[1] = mappers.MMC1
prgrom0, which must contain the reset vector (main).
Last 2 prg banks are merged into 1 16kB bank, to allow linker optimization - hence, 0 must
always be set on bit 6 of bank select, even; also, there is no prgrom1 as a consequence.
t.prgmap is an optional function taking a prgrom bank index and returning its rorg value.
Default is to map even banks to 0x8000, and odd to 0xa000.
chrroms are all 1kB, so they can work with chr A12 inversion enabled or not.
If t.onechrrom is set, only one big chrrom location is created instead.
With default submapper id of 0, this defaults to revision MM3C, which generates a scanline
interrupt at each scanline when counter is loaded with 0.
@ -601,17 +649,16 @@ mappers.MMC3 = function(t)
section{"vectors", org=o+0x3ffa} dc.w nmi, main, irq
end
prgrom = prgrom0
local chrmap = t.chrmap or function(ci, cc) return (ci&7)*0x400 end
local chrstart = 0x8000 + bc*0x2000
local ci, chrstart = 0, 0x8000 + bc*0x2000
local chrmap = t.chrmap or function(ci) return ci*0x400, 0x400, (ci&7)*0x400 end
local cc = t.chrsize//0x400
if t.onechrrom then
chrrom0 = location{chrstart, chrstart + cc*0x400 - 1, rorg=0, name='chrrom'}
else
for ci=0,cc-1 do
local o = chrstart + ci*0x400
_ENV['chrrom'..ci] = location{o, o+0x3ff, rorg=chrmap(ci,cc), name='chrrom'..ci}
end
end
repeat
local off, sz, rorg = chrmap(ci)
sz = sz or t.chrsize - off
local o = off + chrstart
_ENV['chrrom'..ci] = location{o, o+sz-1, rorg=rorg or 0, name='chrrom'..ci}
ci = ci+1
until off + sz >= t.chrsize
chrrom = chrrom0
local a12inv = false
function seta12inv(enabled) a12inv = enabled end
@ -666,11 +713,8 @@ mappers[4] = mappers.MMC3
main MUST be in 0xe000-0xfff9 of last prgrom.
prgroms are numbered from last (0) to first (#-1), so that adding more does not change
prgrom0, which must contain the reset vector (main).
t.prgmap is an optional function taking a prgrom bank index and returning its rorg value.
Default is to map banks in sequence to 0x8000, 0xa000, 0xc000, and 0xe000.
chrroms are all 1kB. Provide t.chrmap if needed, same as t.prgmap.
If t.onechrrom is set, only one big chrrom location is created instead.
chrroms are all 1kB.
]]
mappers.MMC5 = function(t)
if not t then t = {} end
@ -695,17 +739,16 @@ mappers.MMC5 = function(t)
section{"main", org=o} -- enforce entry point in last bank
end
prgrom = prgrom0
local chrmap = t.chrmap or function(ci, cc) return (ci&7)*0x400 end
local chrstart = 0x8000 + bc*0x2000
local ci, chrstart = 0, 0x8000 + bc*0x2000
local chrmap = t.chrmap or function(ci) return ci*0x400, 0x400, (ci&7)*0x400 end
local cc = t.chrsize//0x400
if t.onechrrom then
chrrom0 = location{chrstart, chrstart + cc*0x400 - 1, rorg=0, name='chrrom'}
else
for ci=0,cc-1 do
local o = chrstart + ci*0x400
_ENV['chrrom'..ci] = location{o, o+0x3ff, rorg=chrmap(ci,cc), name='chrrom'..ci}
end
end
repeat
local off, sz, rorg = chrmap(ci)
sz = sz or t.chrsize - off
local o = off + chrstart
_ENV['chrrom'..ci] = location{o, o+sz-1, rorg=rorg or 0, name='chrrom'..ci}
ci = ci+1
until off + sz >= t.chrsize
chrrom = chrrom0
function prgbankmode(mode) if mode then lda #mode end sta 0x5100 end
function chrbankmode(mode) if mode then lda #mode end sta 0x5101 end

95
samples/nes_bank1.l65 Normal file
View File

@ -0,0 +1,95 @@
require'nes'
-- Press A to switch between the two PRG banks.
-- fixed 16kB for prgrom0, 2 other banks of 16kB each mappable at 0x8000
mappers.UxROM{ prgsize=(16+16*2)*1024 }
location(chrrom0)
local font = section("font")
dc.b 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 -- <SPC>
dc.b 0x38,0x38,0x2c,0x64,0x7e,0x46,0xce,0x00,0x38,0x38,0x2c,0x64,0x7e,0x46,0xce,0x00 -- A
dc.b 0xfc,0x62,0x66,0x7c,0x62,0x66,0xfc,0x00,0xfc,0x62,0x66,0x7c,0x62,0x66,0xfc,0x00 -- B
dc.b 0x7c,0xe6,0xc2,0xc0,0xc0,0xe6,0x7c,0x00,0x7c,0xe6,0xc2,0xc0,0xc0,0xe6,0x7c,0x00 -- C
dc.b 0xfc,0x4e,0x46,0x46,0x46,0xce,0xfc,0x00,0xfc,0x4e,0x46,0x46,0x46,0xce,0xfc,0x00 -- D
dc.b 0xfe,0x66,0x60,0x7c,0x60,0x66,0xfe,0x00,0xfe,0x66,0x60,0x7c,0x60,0x66,0xfe,0x00 -- E
dc.b 0xfe,0x66,0x60,0x7c,0x60,0x60,0xf0,0x00,0xfe,0x66,0x60,0x7c,0x60,0x60,0xf0,0x00 -- F
dc.b 0x7c,0xe6,0xc0,0xce,0xc6,0xe6,0x7c,0x00,0x7c,0xe6,0xc0,0xce,0xc6,0xe6,0x7c,0x00 -- G
dc.b 0xee,0x66,0x66,0x7e,0x66,0x66,0xee,0x00,0xee,0x66,0x66,0x7e,0x66,0x66,0xee,0x00 -- H
dc.b 0x3c,0x18,0x18,0x18,0x18,0x18,0x3c,0x00,0x3c,0x18,0x18,0x18,0x18,0x18,0x3c,0x00 -- I
dc.b 0x0e,0x06,0x06,0xc6,0xc6,0xce,0x7c,0x00,0x0e,0x06,0x06,0xc6,0xc6,0xce,0x7c,0x00 -- J
dc.b 0xce,0xdc,0xf8,0xf0,0xf8,0xdc,0xce,0x00,0xce,0xdc,0xf8,0xf0,0xf8,0xdc,0xce,0x00 -- K
dc.b 0xc0,0xc0,0xc0,0xc0,0xc6,0xc6,0xfe,0x00,0xc0,0xc0,0xc0,0xc0,0xc6,0xc6,0xfe,0x00 -- L
dc.b 0xc6,0xee,0xfe,0xd6,0xc6,0xc6,0xc6,0x00,0xc6,0xee,0xfe,0xd6,0xc6,0xc6,0xc6,0x00 -- M
dc.b 0xc6,0xe6,0xf6,0xde,0xce,0xc6,0xc6,0x00,0xc6,0xe6,0xf6,0xde,0xce,0xc6,0xc6,0x00 -- N
dc.b 0x7c,0xee,0xc6,0xc6,0xc6,0xee,0x7c,0x00,0x7c,0xee,0xc6,0xc6,0xc6,0xee,0x7c,0x00 -- O
dc.b 0xfc,0xc6,0xc6,0xc6,0xfc,0xc0,0xc0,0x00,0xfc,0xc6,0xc6,0xc6,0xfc,0xc0,0xc0,0x00 -- P
dc.b 0x7c,0xce,0xc6,0xc6,0xde,0xec,0x7e,0x00,0x7c,0xce,0xc6,0xc6,0xde,0xec,0x7e,0x00 -- Q
dc.b 0xfc,0x66,0x66,0x7c,0x58,0x6c,0xe6,0x00,0xfc,0x66,0x66,0x7c,0x58,0x6c,0xe6,0x00 -- R
dc.b 0x7c,0xc6,0xc0,0x7c,0x06,0xc6,0x7c,0x00,0x7c,0xc6,0xc0,0x7c,0x06,0xc6,0x7c,0x00 -- S
dc.b 0xfe,0x92,0x10,0x10,0x10,0x10,0x38,0x00,0xfe,0x92,0x10,0x10,0x10,0x10,0x38,0x00 -- T
dc.b 0xe6,0xe6,0xc2,0xc2,0xc2,0xe6,0x7c,0x00,0xe6,0xe6,0xc2,0xc2,0xc2,0xe6,0x7c,0x00 -- U
dc.b 0xc6,0xc6,0xc6,0x6c,0x6c,0x38,0x38,0x00,0xc6,0xc6,0xc6,0x6c,0x6c,0x38,0x38,0x00 -- V
dc.b 0xc6,0xc6,0xd6,0xfe,0xee,0xc6,0x82,0x00,0xc6,0xc6,0xd6,0xfe,0xee,0xc6,0x82,0x00 -- W
dc.b 0x86,0xcc,0x78,0x30,0x78,0xcc,0x86,0x00,0x86,0xcc,0x78,0x30,0x78,0xcc,0x86,0x00 -- X
dc.b 0xc6,0xc6,0x6c,0x38,0x18,0x18,0x38,0x00,0xc6,0xc6,0x6c,0x38,0x18,0x18,0x38,0x00 -- Y
dc.b 0x7e,0xce,0x98,0x30,0x62,0xe6,0xfc,0x00,0x7e,0xce,0x98,0x30,0x62,0xe6,0xfc,0x00 -- Z
charset(" abcdefghijklmnopqrstuvwxyz", \x(x + (font.org - font.location.start) // 16))
-- define some text of same length in both swappable PRG banks 1 and 2
location(prgrom1)
local text1 = "bank one"
local sec_text1 = section("text1") byte(text1)
location(prgrom2)
local text2 = "bank two"
local sec_text2 = section("text2") byte(text2)
-- force sec_text2 to have same offset in prgrom2 than sec_text1 in prgrom1,
-- so we can use either address to reference the custom bank data
relate(sec_text1, sec_text2)
-- fixed bank, last 16kB
location(prgrom)
@@nmi @irq rti
joya = 1
curbank = 0
@@switchbank
lda #3
eor curbank
sta curbank
switchprgrom()
-- load screen text in PPU RAM 0x21CA
ppu_addr(0x21ca)
ldy #0 @_loadtxt lda sec_text1,y sta PPUDATA iny cpy ##text1 bne _loadtxt
-- reset scroll position
ppu_addr(0) sta BGSCROL sta BGSCROL
rts
@@main
init()
vblank_waitbegin()
-- load BG palette in PPU RAM
ppu_addr(BGPAL)
for _,v in ipairs{ 0x1f, 0x00, 0x10, 0x20 } do lda #v sta PPUDATA end
-- switch between the two banks
lda #2 sta curbank
jsr switchbank
-- show BG
lda #0x0a sta PPUMASK
-- idle
@_loop
vblank_waitbegin()
read_joy_a(1) bcc _noswitch
lda joya bne _switch
jsr switchbank lda #1 sta joya bne _switch
@_noswitch
lda #0 sta joya
@_switch
jmp _loop
writebin(filename..'.nes')
writesym(filename..'.mlb', 'mesen')
writesym(filename..'.nes', 'fceux')
print(stats)