Nether Bridge

function clc()
    term.clear()
    term.setCursorPos(1,1)
end

function tup()
    while turtle.up() == false  do
        turtle.digUp()
        turtle.attackUp()
    end
end

function tdn()
    while turtle.down() == false do
        turtle.digDown()
        turtle.attackDown()
    end
end

function trt()
    turtle.turnRight()
    while turtle.forward() == false do
        turtle.dig()
        turtle.attack()
    end
end

function tlt()
    turtle.turnLeft()
    while turtle.forward() == false do
        turtle.dig()
        turtle.attack()
    end
end

function tfd()
    while turtle.forward() == false do
        turtle.dig()
        turtle.attack()
    end
end

function tbk()
    if turtle.back() == false then
        turtle.turnRight(2)
    while turtle.forward() == false do
            turtle.dig()
            turtle.attack()
        end
        turtle.turnRight()
        turtle.turnRight()
    else
    end
end

function cup()
    turtle.select(1)
    if turtle.compareUp() == false then
        turtle.select(2)
    while turtle.getItemCount(2) < 1 do
        turtle.select(3)
    while turtle.placeUp() == false do
            turtle.digUp()
            turtle.attackUp()
        end
        end
    else
    end
end

function cfd()
    turtle.select(1)
    if turtle.compare() == false then
        turtle.select(2)
    while turtle.getItemCount(2) < 1 do
        turtle.select(3)
    while turtle.place() == false do
            turtle.dig()
            turtle.attack()
        end
        end
    else
    end
end

function cdn()
    turtle.select(1)
    if turtle.compareDown() == false then
        turtle.select(2)
    while turtle.getItemCount(2) < 1 do
        turtle.select(3)
        while turtle.placeDown() == false do
            turtle.digDown()
            turtle.attackDown()
        end
        end
    else
    end
end


clc()
write('How far forward? ')
x = read()
j = 0
clc()
print('Mining in progress...')
print()
print()
print('<                         >')
term.setCursorPos(13,5)
print('0%')

for i=1,x-1 do
    if j%11 == 0 then
        turtle.turnRight()
        turtle.turnRight()
        turtle.select(16)
        turtle.place()
        turtle.select(1)
        turtle.turnRight()
        turtle.turnRight()
    elseif (j-5)%11 == 0 then
        turtle.turnRight()
        turtle.turnRight()
        turtle.select(16)
        turtle.place()
        turtle.select(1)
        turtle.turnRight()
        turtle.turnRight()
    end
    j = j+1
    tfd()
    cdn()
    cfd()
    tup()
    cfd()
    tup()
    cfd()
    cup()
    tlt()
    cfd()
    cup()
    turtle.turnRight()
    cfd()
    tdn()
    cfd()
    turtle.turnLeft()
    cfd()
    tdn()
    cfd()
    cdn()
    turtle.turnRight()
    cfd()
    turtle.turnRight()
    tfd()
    tfd()
    cfd()
    cdn()
    turtle.turnLeft()
    cfd()
    tup()
    cfd()
    turtle.turnRight()
    cfd()
    tup()
    cfd()
    cup()
    turtle.turnLeft()
    cfd()
    turtle.turnLeft()
    tfd()
    turtle.turnRight()
    tdn()
    tdn()

    p = (i/x-(i/x)%0.0001)*100
    term.setCursorPos(13,5)
    n = tostring(p)
    term.clearLine()
    print(n .. '%')
    term.setCursorPos(2,4)
    while p>4 do
        p = p-4
        write('=')
    end
end

term.setCursorPos(13,5)
term.clearLine()
print('100%')
print()
print('Mining complete.')