main.lua

local bit = require("bit")
local BP = require("bytepusher")

-- bytepusher metatable handler
local core = {}

-- constants
local INTENSITY = 0x33
local OPAQUE = 0xFF

function love.load(arg)
    local file = love.filesystem.newFile(arg[1])
    local status, result = file:open("r")

    if (status) then
        -- start bytepusher interpreter
        core = BP:new()
        core.load(file)
    else
        print("Result: " .. result)
        file:close()
    end
end

function love.update(dt)
    local cap = 1 / 30
    if dt < cap then
        love.timer.sleep(cap - dt)
    end
    core:cycle()
end

function love.draw()
    local r, g, b = 0, 0, 0
    local zz = bit.lshift(core.mem[5], 16)

    -- set bg to black
    love.graphics.clear(0, 0, 0, OPAQUE)

    for yy = 0, 255 do
        local _yy = bit.lshift(yy, 8)
        local colors = {}
        for xx = 0, 255 do
            local c = core.mem[bit.bor(zz, _yy, xx)]
            colors[xx] = c
        end
    
        for xx = 0, 255 do
            local color = colors[xx]
    
            -- Multi pixel color (web safe palette)
            if (color <= 216) then
                b = (color % 6) * INTENSITY
                color = color / 6
                g = (color % 6) * INTENSITY
                color = color / 6
                r = (color % 6) * INTENSITY
    
                r = r / OPAQUE
                g = g / OPAQUE
                b = b / OPAQUE
    
                love.graphics.setColor(r, g, b, OPAQUE)
            elseif (color >= 217 and color <= 255) then
                -- black pixel color
                love.graphics.setColor(0, 0, 0, OPAQUE)
            else
                -- White pixel color
                love.graphics.setColor(OPAQUE, OPAQUE, OPAQUE, OPAQUE)
            end
    
            -- draw pixel
            love.graphics.rectangle("fill", xx, yy, 1, 1)
        end
    end    
end

function love.keypressed(key)
    poll(key)
end

function love.keyreleased(key)
    poll(key)
end

function poll(key)
    local key_data = bit.bor(bit.lshift(core.mem[0], 8), core.mem[1])

    if (core.keyboard[key]) then
        key_data = bit.bxor(key_data , bit.lshift(1, core.keyboard[key]))
    end

    core.mem[0] = bit.rshift(key_data, 8)
    core.mem[1] = bit.band(key_data, 0xFF)
end