teest

local component = require("component")
local gpu = component.gpu
local keyboard = require("keyboard")
local computer = require("computer")
local bit32 = require("bit32")

-- Constants
local MEMORY_SIZE = 16 * 1024 * 1024 -- 16 MiB
local BANK_SIZE = 1 * 1024 * 1024 -- 1 MiB per bank
local NUM_BANKS = 16
local SCREEN_WIDTH = 256
local SCREEN_HEIGHT = 256
local CYCLES_PER_FRAME = 65536

-- Initialize memory banks
local memoryBanks = {}
for i = 1, NUM_BANKS do
    memoryBanks[i] = {}
    for j = 1, BANK_SIZE do
        memoryBanks[i][j] = 0
    end
end

local currentBank = 1

-- Memory access with bank switching
local function memoryRead(address)
    local bank = bit32.rshift(address - 1, 20) + 1
    local offset = bit32.band(address - 1, BANK_SIZE - 1) + 1
    return memoryBanks[bank][offset]
end

local function memoryWrite(address, value)
    local bank = bit32.rshift(address - 1, 20) + 1
    local offset = bit32.band(address - 1, BANK_SIZE - 1) + 1
    memoryBanks[bank][offset] = value
end

-- CPU implementation
local function cpu_cycle()
    local pc = bit32.bor(bit32.lshift(memoryRead(3), 16), bit32.lshift(memoryRead(4), 8), memoryRead(5))
    local a = bit32.bor(bit32.lshift(memoryRead(pc + 1), 16), bit32.lshift(memoryRead(pc + 2), 8), memoryRead(pc + 3))
    local b = bit32.bor(bit32.lshift(memoryRead(pc + 4), 16), bit32.lshift(memoryRead(pc + 5), 8), memoryRead(pc + 6))
    memoryWrite(a, memoryRead(b))
    return a + 3
end

-- Color palette initialization
local colorPalette = {}
for i = 0, 215 do
    local r = bit32.rshift(i, 4) * 51
    local g = bit32.band(bit32.rshift(i, 2), 3) * 51
    local b = bit32.band(i, 3) * 51
    colorPalette[i] = {r / 255, g / 255, b / 255}
end

-- Main emulation loop
local function emulate()
    -- Set up screen
    gpu.setResolution(SCREEN_WIDTH, SCREEN_HEIGHT)

    local lastTime = computer.uptime()
    while true do
        -- Handle input
        local keyState = 0
        for i = 0, 15 do
            if keyboard.isKeyDown(tostring(i)) then
                keyState = bit32.bor(keyState, bit32.lshift(1, i))
            end
        end
        memoryWrite(1, bit32.rshift(keyState, 8))
        memoryWrite(2, bit32.band(keyState, 0xFF))

        -- Run CPU cycles
        for _ = 1, CYCLES_PER_FRAME do
            local newPC = cpu_cycle()
            memoryWrite(3, bit32.rshift(newPC, 16))
            memoryWrite(4, bit32.band(bit32.rshift(newPC, 8), 0xFF))
            memoryWrite(5, bit32.band(newPC, 0xFF))
        end

        -- Update screen
        local screenPtr = bit32.lshift(memoryRead(6), 16)
        for y = 1, SCREEN_HEIGHT do
            for x = 1, SCREEN_WIDTH do
                local color = memoryRead(screenPtr + (y-1)*SCREEN_WIDTH + x)
                local r, g, b = table.unpack(colorPalette[color])
                gpu.setForeground(gpu.getPaletteColor(gpu.setPaletteColor(1, r, g, b)))
                gpu.set(x, y, "▀")
            end
        end

        -- Frame timing
        local currentTime = computer.uptime()
        local sleepTime = (1/60) - (currentTime - lastTime)
        if sleepTime > 0 then
            os.sleep(sleepTime)
        end
        lastTime = currentTime

        -- Check for exit condition
        if keyboard.isKeyDown("q") then
            break
        end
    end
end

-- Load ROM from /home/ directory
local function loadROMFromHome(filename)
    local file = io.open("/home/" .. filename, "rb")
    if file then
        local content = file:read("*all")
        file:close()
        for i = 1, #content do
            memoryWrite(i, string.byte(content, i))
        end
        return true
    end
    return false
end

-- Main
print("BytePusher Emulator for OpenComputers")
print("Enter the name of your ROM file (located in /home/):")
local romName = io.read()

if loadROMFromHome(romName) then
    print("ROM loaded successfully from /home/")
    print("Emulation starting. Press 'Q' to quit.")
    emulate()
    print("Emulation ended.")
else
    print("Failed to load ROM from /home/. Make sure the file exists and is readable.")
end