_set_fps(60)𝘩=64★={}s=.001𝘴=sin
while(#★>=0)add(★,★)
poke(24337,ord('░⁴웃\t\n♥⬇️⬇️³³⬅️⌂\0\0',1,14))𝘢=abs
fillp(▒\1)𝘤=cos?"⁶c0⁶w⁶t  ᶜe★"
function 𝘭(𝘺)all(★)for t=0,█,s do
w=r-r/3*𝘴(t*7%█)x=w*𝘤(t)𝘹=𝘢(x)z=w*𝘴(t)l=(x*x+y*y+z*z)^.5b=1+𝘢(x/5+y/3+z)/l*5
if(y>=11-x^2/200and y<=27-x^2/83+𝘹*.1or pget(𝘹,-y)>0)b=8
sset(𝘩+x,𝘺+y,b+((b+█)\1-b\1)*8)end end
y=0while(y<9)r=2+y/16𝘭(22)y+=1
a=0while(a<.43)d=30+15*𝘢(𝘴(a))y=d*𝘤(a)r=d*𝘴(a)𝘭(𝘩)a+=s
function p(v)poke2(d,v)d+=𝘥 end
𝘥=2𝘮=12280d=𝘮 for i=1,84do n=ord('@/\0」@)t𝘸ᶜᶜらᶠᶠᵉᵉ⁘⁘き⁙⁙き◝◝■■ら●⬅️ᵉᵉ…エせらめぬ$+07<70+は$,08<80,ャ◝ほ$)05<50)は$*06<60*&+2◆72◆せ*ャは',i)
if(n<128)p(n)d-=1else for _=0,n\16%8do p(%(d-n%16*2-2))end end
p(-32384)p(770)
d+=316𝘥=68v=7169p(v+24)p(v+32)p(v)p(v)music()
𝘳=0function 𝘱()p(%[email protected])c+=2end
::_::?"⁶1"
while(𝘳-8&31!=stat(20))d=12800+𝘳%32*2a=𝘳%128+𝘮+8c=𝘮 𝘱()𝘱()a+=128𝘱()𝘱()𝘳+=1
a=t()*.1c=𝘤(a)s=𝘴(a)𝘻=s+2for y=-𝘩,𝘩 do all(★)for x=-𝘩,𝘩 do v=𝘩+(s*x+c*y)*𝘻&127
𝘷=v-73if(𝘷>0)v-=𝘷*𝘴(a*16)/2
k=sget(𝘩+(c*x-s*y)*𝘻&127,v)d=k\8k%=8if(k>0and v<30)k+=7
pset(𝘩+x,𝘩+y,k+(k+d)*16)end end goto _

-- The standalone PICO-8 app may handle 60fps, depending on your device.
-- Remove this to run at 30fps.
_set_fps(60)

-- The "all star" virtual CPU exploit!
--
-- PICO-8's all(c) function very nicely refunds some virtual cpu cycles via 
-- "_refund_cpu_((#c >= 16) and -16 or -#c", where _refund_cpu is an
-- internal function that actually adds to the virtual cycles consumed;
-- so a negative argument will refund cycles (cart goes faster), 
-- and a positive argument will consume cycles (cart goes slower).
--
-- all(c) where #c==0 causes no extra cycles to be refunded or consumed.
-- all(c) where #c>0 and #c<16 results in #c cycles being refunded.
-- all(c) where #c>=16 results in only 16 cycles being refunded.
--
-- To exploit _refund_cpu and achieve undeserved cycles refunded we
-- need #c to be less than 16 but -#c to be negative and large.
--
-- Negative numbers don't seem to help, even if we could make a negative
-- sized table. -#c will just be positive so _refund_cpu will actually 
-- consume extra cycles and the cart will go slower!
--
-- Fortunately for us, in 1945 John von Neumann anticipated humanity's
-- need to exploit fantasy consoles 76 years hence and prankishly proposed
-- using twos complement to represent negative numbers in future so-
-- called "electronic stored-program digital computers".
--
-- In PICO-8, 0x8000 == 32768 == -32768 == -0x8000. So if we can make
-- #c==-32768 then all(c) will call _refund_cpu(-#c == -32768) and John's 
-- prescient plan will reach its triumphant culmination.
--
-- In lua the __len operation on a table's metatable will be called by #c.
-- So we could do:
--
-- c={__len=function() return -32768 end}
-- setmetatable(c,c)
--
-- but we can do it in fewer characters if we have plenty of memory:
star={}
while(#star>=0)add(star,star)
-- since 32767+1 == -32768 this loops until #star == -32768.
-- now all(star) will call _refund_cpu(-32768) and time will flow backwards!
--
-- Note: it doesn't matter what we add to the table but add (★,★) looks
-- spookily like a malevolent pumpkin staring hungrily through the depths of 
-- time...

-- Set the screen palette, equivalent to pal({...},1) but shorter.
poke(0x5f11,ord("\x84\x04\x89\x09\x0a\x87\x83\x83\x03\x03\x8b\x8a\x00\x00",1,14))

-- The cart's palette is:
-- Color 0 is unassigned as it defaults to zero (black), as desired.
-- Colors 1-6 define a brown/orange/yellow gradient for the pumpkin's skin.
-- Colors 7-12 define a green gradient for the pumpkin's stalk.
-- Color 13 is black because the approximate math behind the pumpkin actually
-- generates a 7th gradient color in the top-middle pixel of the stalk,
-- and setting that to black results in a pleasing "fork" in the stalk, if
-- you look closely and squint a bit.
-- Color 14 is black because PICO-8's default spritesheet has a star drawn
-- in color 7 in the top-left; later we'll see we add 7 to the spritesheet
-- color near the top of the spritesheet, and setting color 14 to black was
-- cheaper than clearing the unwanted pixels.
-- (In retrospect we could have shifted the palette entries up one index
-- and had the gradients start at color 2, to avoid the duplicate blacks
-- and thereby saved two chars).

-- In PICO-8 ▒ is a variable set to 0b0101101001011010.1 which is a checkered
-- fill pattern. We need to remove the .1 transparency bit using \1.
fillp(▒\1)

-- P8SCII code to clear the screen, set wide mode on, set tall mode on, skip
-- a couple spaces, use color 14 (black but non-zero) and draw a star. We will
-- pget these pixels later to cheaply carve the pumpkin's eyes (upside-down).
print("⁶c0⁶w⁶t  ᶜe★")

-- plot_pumpkin_row draws one row of either the pumpkin face or stalk to the
-- spritesheet. We draw the pumpkin to the spritesheet once on startup, then
-- each frame read from the spritesheet to render it to the screen.
-- We iterate angles to derive individual 3d pixel positions on the surface,
-- then completely fake lighting in a mathematically unsound yet surprisingly
-- pleasing way.
-- The resulting pixel is assigned a pair of colors to represent a smoother
-- gradient via the fill pattern. So in fact there are 11 "orange" values 
-- counting in-between colors, plus one for the mouth/eyes, and 12 "green" 
-- values.
-- PICO-8 only stores 4 bits per pixel in the spritesheet, so we actually only
-- store the uncolored lighting value which happens to coincide with the
-- orange gradient colors.
-- When rendering the pumpkin each frame, we check each pixel's y coordinate
-- to determine whether it was a stalk, then shift the color to the green 
-- gradient by adding 7. (This is why that wayward star in the default 
-- spritesheet ends up with color 14, which is why we set index 14 to black.)
function plot_pumpkin_row(yofs)
 -- exploit: accelerate this slow startup code!
 all(star)
 for t=0,.5,.001 do
  -- https://www.shadertoy.com/view/4tBcRV is a great demonstration of this
  -- "pumpkin segment" math to get the distance to the surface from the
  -- vertical axis.
  w=r-r/3*sin(t*7%.5)
  -- x is screen position relative to the origin (middle of the screen)
  x=w*cos(t)
  absx=abs(x)
  -- z is distance from XY plane through pumpkin's center
  z=w*sin(t)
  -- Fake diffuse lighting using surface position as normal and an
  -- unnormalized light vector. The value is put in the range 1-6.
  l=(x*x+y*y+z*z)^.5
  b=1+abs(x/5+y/3+z)/l*5
  -- Check if this pixel is part of the mouth (first expression) or
  -- the eyes (second expression) by reading the star we printed earlier.
  if (y>=11-x^2/200 and y<=27-x^2/83+absx*.1) or (pget(absx,-y)>0) then
   b=8 -- base color is 0, and the high bit=8 indicates a 2-color pattern
  end
  -- If the pixel value's fractional part is >= 0.5, then set the high bit=8
  -- to remember to use a two color gradient.
  sset(64+x,yofs+y,b+((b+.5)\1-b\1)*8)
 end
end
-- Plot the pumpkin stalk to the spritesheet
y=0
while y<9 do
 -- Stalk is thicker at the base
 r=2+y/16
 -- Plot one row of the stalk
 plot_pumpkin_row(22)
 y+=1
end
-- Plot the pumpkin face to the spritesheet
a=0
while a<.43 do
 -- Distance to each horizontal slice
 d=30+15*abs(sin(a))
 -- y coordinate of slice, relative to the screen origin
 y=d*cos(a)
 -- Horizontal radius of slice
 r=d*sin(a)
 -- Plot one row of the face
 plot_pumpkin_row(64)
 a+=.001
end

-- Utility function to poke2 a value to the global 'dst' and advance dst 
-- by 'dststep'. Reused with two different dststep values.
function poke2_step(v)
 poke2(dst,v)
 dst+=dststep
end

-- Uncompress the music data
--
-- The uncompressed music data has some per-channel values (4 words), plus two
-- sequences of 128 note pitches (256 bytes). 
-- The per-channel word values define the SFX instrument, volume and effect. 
-- Each note's pitch is added to this value when it's written to the SFX.
-- Channel 0 is 0x2f40: organ, volume 7, vibrato. (sequence A)
-- Channel 1 is 0x1900: pulse, volume 4, slide. (sequence A)
-- Channel 2 is 0x2940: organ, volume 4, vibrato. (sequence B)
-- Channel 3 is 0x5774: noise, volume 3, fade out. (sequence B, pitch offset -12)
--
-- We use simple LZ style compression customized for the input. All the pitches
-- are in the range 0-63, and serendipitously the per-channel words above also
-- only have bytes less than 0x80, so we use bit 7 to mark offset/length pairs.
-- It turns out the sequences have a lot of repetition, and limiting the offset
-- to multiples of 2 between 2-32 and length to multiples of 2 between 2-16
-- works well and packs into 8 bits.
--
-- The sound data is poked to just before 0x3100 so that the dst pointer is
-- ready to setup music pattern data after uncompressing.
--
-- Counting the compressed pitches plus uncompression code, 177 chars are 
-- used in the final cart, compared to 256 bytes for the raw pitches.
snddata=0x3100-(256+8)
dststep=2
dst=snddata
-- Iterate compressed music data bytes
for i=1,84 do
 n=ord("\x40\x2f\x00\x19\x40\x29\x74\x57\x0c\x0c\xc0\x0f\x0f\x0e\x0e\x14\x14\xa0\x13\x13\xa0\xff\xff\x11\x11\xc0\x86\x8b\x0e\x0e\x90\xcf\xa7\xc0\xbb\xb0\x24\x2b\x30\x37\x3c\x37\x30\x2b\xb3\x24\x2c\x30\x38\x3c\x38\x30\x2c\xfb\xff\xb7\x24\x29\x30\x35\x3c\x35\x30\x29\xb3\x24\x2a\x30\x36\x3c\x36\x30\x2a\x26\x2b\x32\x8f\x37\x32\x8f\xa7\x2a\xfb\xb3",i)
 if n<128 then
  -- This is a payload byte, poke it
  poke2_step(n)
  -- Our utility function writes words, so step back a byte
  dst-=1
 else
  -- This is an offset/length pair; copy from prior uncompressed data, word by word.
  -- (Allows reading words just copied to get repeated subsequences)
  for _=0,n\16%8 do
   poke2_step(%(dst-n%16*2-2))
  end 
 end
end
-- Poke the pattern data; we set up a single pattern that references SFX 0,1,2,3 and loops.
poke2_step(0x8180)
poke2_step(0x0302)
-- Skip dst to 0x3200+64 where we will poke SFX control data
dst+=316
-- Each SFX is 68 bytes
dststep=68
v=0x1c01
-- Channel 0's SFX control is 0x1c19: speed=28, reverb=1
-- Channel 1's SFX control is 0x1c21: speed=28, reverb=1, detune=1
-- Channel 2's SFX control is 0x1c01: speed=28
-- Channel 3's SFX control is 0x1c01: speed=28
poke2_step(v+0x18)
poke2_step(v+0x20)
poke2_step(v)
poke2_step(v)
-- Same as music(0); starts the music
music()

-- sndrow tracks which music row we're about to stream out.
-- sndrow%128 is the note index to read from the music data.
-- sndrow%32 is the SFX row to poke.
sndrow=0

-- poke_note_step is a utility function which reads the per-
-- channel word value, and adds it to the current sequence's
-- pitch value, then writes it to the SFX.
function poke_note_step()
 -- Note: dststep is still 68, so this will advance the dst
 -- pointer to the next SFX.
 -- Add word per-channel value to byte sequence pitch.
 poke2_step(%[email protected])
 -- Advance to the next per-channel word.
 c+=2
end

::mainloop::
 -- Flip
 print("⁶1")
 -- Keep 8 notes ahead of the current music playback row streamed
 -- to SFX 0-3. (If doing dynamic gameplay sounds reduce this to 2)
 -- Note: I tried instead setting up 16 SFX to contain the entire song
 -- but that used more chars than the streaming version. Streaming
 -- would also allow dynamic music - with a few more chars we could
 -- have the channels fade in one at a time like the C64 version of
 -- Cauldron...
 while sndrow-8&31 != stat(20) do
  -- Setup dst to channel 0's (i.e. SFX 0's) current streaming row.
  dst=0x3200 + sndrow%32*2
  -- Address of sequence A's streaming pitch
  a=sndrow%128 + snddata + 8
  -- Address of channel 0's per-channel values
  c=snddata
  -- Channel 0 and 1 share sequence A's pitches
  poke_note_step()
  poke_note_step()
  a+=128
  -- Channel 2 and 3 share sequence B's pitches
  poke_note_step()
  poke_note_step()
  sndrow+=1
 end

 -- Render the pumpkin, pixel by pixel
 a=t()*.1
 c=cos(a)
 s=sin(a)
 zoom=s+2
 -- For each y coord relative to the middle of the screen
 for y=-64,64 do
  -- Exploit: accelerate this slow loop!
  all(star)
  -- For each x coord relative to the middle of the screen
  for x=-64,64 do 
   -- Rotzoom screen x,y to get spritesheet coords u,v
   u=64+(c*x-s*y)*zoom & 127
   v=64+(s*x+c*y)*zoom & 127
   -- Animate the pumpkin's jaw up and down
   jawv=v-73
   if jawv>0 then
    v-=jawv*sin(a*16)/2
   end
   -- Get spritesheet pixel and separate into base color value 'b'
   -- and dither flag 'd'
   b=sget(u,v)
   d=b\8
   b%=8
   -- Recolor the stalk from shades of orange to shades of green.
   -- Note: The stalk actually should start at v=30, but leaving that
   -- row orange fakes a little perspective on top of the center slice
   -- of the pumpkin face!
   -- Note: This is also where that unwanted default 'x' in the 
   -- spritesheet gets recolored to color 14, which we set to black in
   -- the palette to hide it. It's drawn every frame!
   if (b>0 and v<30) then
    b+=7
   end
   -- Plot the pixel on the screen. Note the second color for the dither
   -- pattern goes into the high nibble.
   pset(64+x,64+y,b+(b+d)*16)
  end
 end 
goto mainloop

poke4(dst,peek4(src,len))

poke4(0x6000,peek4(0x0000,2048))