(module
  (memory (export "m") 2 16)
  (global $x (mut i32) (i32.const 80))
  (global $y (mut i32) (i32.const 45))

  ;; Paint an RGBA pixel at (x,y). Out-of-bounds coordinates are ignored.
  (func $px (param $x i32) (param $y i32) (param $c i32)
    (if (i32.and
          (i32.and (i32.ge_s (local.get $x) (i32.const 0))
                   (i32.lt_s (local.get $x) (i32.const 160)))
          (i32.and (i32.ge_s (local.get $y) (i32.const 0))
                   (i32.lt_s (local.get $y) (i32.const 90))))
      (then
        (i32.store
          (i32.shl
            (i32.add (i32.mul (local.get $y) (i32.const 160)) (local.get $x))
            (i32.const 2))
          (local.get $c)))))

  ;; ABI: f(frame, input, seed) -> framebuffer byte offset.
  (func (export "f") (param $frame i32) (param $input i32) (param $seed i32) (result i32)
    (local $i i32) (local $h i32) (local $dx i32) (local $dy i32)

    ;; First frame: a deterministic, nearly black sky with tiny seeded stars.
    (if (i32.eqz (local.get $frame))
      (then
        (local.set $i (i32.const 0))
        (loop $sky
          (local.set $h
            (i32.xor
              (i32.mul (local.get $i) (i32.const 1103515245))
              (local.get $seed)))
          (i32.store
            (i32.shl (local.get $i) (i32.const 2))
            (select
              (i32.const -723369985) ;; RGBA: 255,225,225,212
              (i32.const -16444398)  ;; RGBA: 18,18,5,255
              (i32.eqz (i32.and (local.get $h) (i32.const 1023)))))
          (local.set $i (i32.add (local.get $i) (i32.const 1)))
          (br_if $sky (i32.lt_u (local.get $i) (i32.const 14400))))))

    ;; Seven input bits: arrows move, A blooms, B scatters, Start returns home.
    (if (i32.and (local.get $input) (i32.const 1))
      (then (global.set $x (i32.sub (global.get $x) (i32.const 1)))))
    (if (i32.and (local.get $input) (i32.const 2))
      (then (global.set $x (i32.add (global.get $x) (i32.const 1)))))
    (if (i32.and (local.get $input) (i32.const 4))
      (then (global.set $y (i32.sub (global.get $y) (i32.const 1)))))
    (if (i32.and (local.get $input) (i32.const 8))
      (then (global.set $y (i32.add (global.get $y) (i32.const 1)))))
    (if (i32.and (local.get $input) (i32.const 64))
      (then (global.set $x (i32.const 80)) (global.set $y (i32.const 45))))

    ;; Clamp the seed to the visible world.
    (if (i32.lt_s (global.get $x) (i32.const 1)) (then (global.set $x (i32.const 1))))
    (if (i32.gt_s (global.get $x) (i32.const 158)) (then (global.set $x (i32.const 158))))
    (if (i32.lt_s (global.get $y) (i32.const 1)) (then (global.set $y (i32.const 1))))
    (if (i32.gt_s (global.get $y) (i32.const 88)) (then (global.set $y (i32.const 88))))

    ;; Movement leaves a living green-gold trail.
    (call $px (global.get $x) (global.get $y) (i32.const -10832640))

    ;; A: plant a nine-pixel flower. Its petals change with time.
    (if (i32.and (local.get $input) (i32.const 16))
      (then
        (call $px (global.get $x) (global.get $y) (i32.const -18752))
        (call $px (i32.sub (global.get $x) (i32.const 2)) (global.get $y) (i32.const -8846593))
        (call $px (i32.add (global.get $x) (i32.const 2)) (global.get $y) (i32.const -8846593))
        (call $px (global.get $x) (i32.sub (global.get $y) (i32.const 2)) (i32.const -8846593))
        (call $px (global.get $x) (i32.add (global.get $y) (i32.const 2)) (i32.const -8846593))
        (call $px (i32.sub (global.get $x) (i32.const 1)) (i32.sub (global.get $y) (i32.const 1)) (i32.const -32385))
        (call $px (i32.add (global.get $x) (i32.const 1)) (i32.sub (global.get $y) (i32.const 1)) (i32.const -32385))
        (call $px (i32.sub (global.get $x) (i32.const 1)) (i32.add (global.get $y) (i32.const 1)) (i32.const -32385))
        (call $px (i32.add (global.get $x) (i32.const 1)) (i32.add (global.get $y) (i32.const 1)) (i32.const -32385))))

    ;; B: cast eight sparks farther into the dark.
    (if (i32.and (local.get $input) (i32.const 32))
      (then
        (local.set $i (i32.const 0))
        (loop $sparks
          (local.set $h (i32.add (i32.mul (local.get $frame) (i32.const 17)) (i32.mul (local.get $i) (i32.const 73))))
          (local.set $dx (i32.sub (i32.and (local.get $h) (i32.const 15)) (i32.const 7)))
          (local.set $dy (i32.sub (i32.and (i32.shr_u (local.get $h) (i32.const 4)) (i32.const 15)) (i32.const 7)))
          (call $px (i32.add (global.get $x) (local.get $dx)) (i32.add (global.get $y) (local.get $dy)) (i32.const -18752))
          (local.set $i (i32.add (local.get $i) (i32.const 1)))
          (br_if $sparks (i32.lt_u (local.get $i) (i32.const 8))))))

    ;; A pulsing white cursor: the last seed itself.
    (call $px (global.get $x) (global.get $y)
      (select (i32.const -1) (i32.const -18752)
        (i32.eqz (i32.and (local.get $frame) (i32.const 8)))))
    (i32.const 0))
)