# Interface implementation Ball And Beam ====================================================

export BallAndBeam, BallAndBeamSimulator, BallAndBeamType

struct BallAndBeam <: PhysicalProcess
    h::Float64
end
BallAndBeam() = BallAndBeam(0.01)

struct BallAndBeamSimulator <: SimulatedProcess
    h::Float64
end
BallAndBeamSimulator() = BallAndBeamSimulator(0.01)

const BallAndBeamType = Union{BallAndBeam, BallAndBeamSimulator}
num_outputs(p::BallAndBeamType) = 2
num_inputs(p::BallAndBeamType)  = 1
outputrange(p::BallAndBeamType) = [(-10,10),(-1,1)] # Beam angle, Ball position
inputrange(p::BallAndBeamType)  = [(-10,10)]
isstable(p::BallAndBeamType)    = false
isasstable(p::BallAndBeamType)  = false
sampletime(p::BallAndBeamType)  = p.h

control(p::BallAndBeam, u)  = ccall((:comedi_write, comedipath),Int32,
                                        (Int32,Int32,Int32,Int32),0,1,1,num2io(u[1]))
measure(p::BallAndBeam)     = io2num(ccall((:comedi_read,comedipath), Int32,
                                        (Int32,Int32,Int32), 0,0,0))

control(p::BallAndBeamSimulator, u)  = error("Not yet implemented")
measure(p::BallAndBeamSimulator)     = error("Not yet implemented")

const comedipath = Pkg.dir("LabProcesses","c","comedi_bridge.so")
const conversion = 65535/20
io2num(x) = x/conversion -10            # Converts from io to float
num2io(x) = round(Int32,x*100 + 2048)   # Converts from regular number to io

initialize(p::BallAndBeam)  = ccall((:comedi_start, comedipath),Int32,(Int32,), 0)
finalize(p::BallAndBeam)    = (control(p,0);ccall((:comedi_stop, comedipath),Int32,(Int32,), 0))
initialize(p::BallAndBeamSimulator)  = nothing
finalize(p::BallAndBeamSimulator)    = nothing