L33t Interpreter

local args = {...}
local memory = {}
local instPointer = 1
local memPointer = 1
local running = true

local function incInst(i)
    instPointer = instPointer+1
end

local function decInst(i)
    instPointer = instPointer-1
end

local function incMemPoint(i)
    memPointer = memPointer+(i and i or 1)
end

local function decMemPoint(i)
    memPointer = memPointer-(i and i or 1)
end

local function incMem(i)
    if(memory[memPointer] == nil) then memory[memPointer] = 0 end
    memory[memPointer] = memory[memPointer]+(i and i or 1)
end

local function decMem(i)
    if(memory[memPointer] == nil) then memory[memPointer] = 0 end
    memory[memPointer] = memory[memPointer]-(i and i or 1)
end

local function getCurMem()
    return memory[memPointer]
end

local function getCurInst()
    return memory[instPointer]
end

local function wrt()
    write(string.char(getCurMem()))
end

local opcodes = {
    NOP = 0,
    WRT = 1,
    RD = 2,
    IF = 3,
    EIF = 4,
    FWD = 5,
    BAK = 6,
    INC = 7,
    DEC = 8,
    CON = 9,
    END = 10
}

local operations = {
    [opcodes.NOP] = function()
        incInst()
    end,
    [opcodes.WRT] = function()
        wrt()
        incInst()
    end,
    [opcodes.RD] = function()
        memory[memPointer] = ((read()):sub(1,1)):byte()
        incInst()
    end,
    [opcodes.IF] = function()
        if(getCurMem() == 0) then
            local found = false
            while not found do
                incInst()
                if(getCurInst() == opcodes.EIF) then
                    found = true
                end
            end
            incInst()
        else
            incInst()
        end
    end,
    [opcodes.EIF] = function()
        if(getCurMem() ~= 0) then
            local found = false
            while not found do
                decInst()
                if(getCurInst() == opcodes.IF) then
                    found = true
                end
            end
            incInst()
        else
            incInst()
        end
    end,
    [opcodes.FWD] = function()
        incInst()
        incMemPoint(getCurInst()+1)
        incInst()
    end,
    [opcodes.BAK] = function()
        incInst()
        decMemPoint(getCurInst()+1)
        incInst()
    end,
    [opcodes.INC] = function()
        incInst()
        incMem(getCurInst()+1)
        incInst()
    end,
    [opcodes.DEC] = function()
        incInst()
        decMem(getCurInst()+1)
        incInst()
    end,
    [opcodes.CON] = function()
        --Nope
    end,
    [opcodes.END] = function()
        running = false
    end
}

if(#args == 0) then error("N0p3.",0) end
if(not fs.exists(args[1])) then error("L0L!!1!1!! n0 l33t pr0gr4m l04d3d, sUxX0r!",0) end

local lines = {}
local handle = fs.open(shell.resolve(args[1]),"r")
local content = handle.readAll()
handle.close()

for line in content:gmatch("[^ \n]+") do
    if line:sub(0,2) ~= "//" then
        for word in line:gmatch("[^ \t]+") do
            local i = 0
            for ch in word:gmatch(".") do
                if(tonumber(ch)) then
                    i = i+tonumber(ch)
                end
            end
            memory[#memory+1] = i
        end
    end
end

memPointer = #memory+1
memory[memPointer] = 0

while running do
    local opc = getCurInst()
    if(opc > 10) then
        error("F00l! teh c0d3 c4n'7 b3 0v3r t3n!!!1!",0)
    end
    operations[opc]()
end