8bitworkshop/presets/vcs/ecs/random.ecs

component Random8
  seed: 0..255 default 1 // TODO: default = 1, or seed?
end

system Random
  on nextrand8 do foreach [Random8]
  ---
  lda {{<seed}}
  lsr
  bcc :+
  eor #$d4
:
  sta {{<seed}}
  ---
  on prevrand8 do foreach [Random8]
  ---
  lda {{<seed}}
  asl
  bcc :+
  eor #$a9
:
  sta {{<seed}}
  ---
  /* add entropy via joystick inputs */
  on preframe do foreach [Random8]
  ---
  lda {{<seed}}
  eor SWCHA
  beq :+
  sta {{<seed}}
:
  ---
end