Read/write an array of bits in PICO-8

bitarray.lua

buffer_base = 0x4300
buffer_width = 127
buffer_height = 127

function init()
  memset(buffer_base, 0, (buffer_width * buffer_height) / 8)
end

function set(x, y, value)
  local offset = (x + (buffer_width * y))
  local mem_offset = offset / 8
  local shift = offset % 8

  local current = peek(buffer_base + mem_offset)
  if value == 0 then
    poke(buffer_base + mem_offset, current & ~(1 << shift))
  else
    poke(buffer_base + mem_offset, current | (1 << shift))
  end
end

function get(x, y)
  local offset = (x + (buffer_width * y))
  local mem_offset = offset / 8
  local shift = offset % 8
  return (peek(buffer_base + mem_offset) >> shift) & 1
end