import os
import sys
import ctypes

def LoadDLL() :
    # load the DLL with linux or windows specific invocations.
    # os.name is 'posix', 'nt', 'os2', 'mac', 'ce' or 'riscos'
    message = 'The required dll nicaiu was not found.'
    if os.name == 'posix' :
        try:
            dll = ctypes.cdll.LoadLibrary("nicaiu.so")
            #dll = ctypes.CDLL("nicaiu.so")         # create an instance of a dll
        except :
            dll = 0
    elif os.name == 'nt' :
        # cdll loads libraries which export functions using the standard cdecl calling convention.
        # windll libraries call functions using the stdcall calling convention.
        try:
            dll = ctypes.windll.nicaiu
            #dll = ctypes.cdll.somelibrary
        except :
            dll = 0
    else :
        message = 'This operating system is not supported.'
        dll = 0
    return dll, message

class Types :
    def __init__(self) :
        self.int32 = ctypes.c_long
        self.uInt32 = ctypes.c_ulong
        self.uInt64 = ctypes.c_ulonglong
        self.float64 = ctypes.c_double
        self.task_handle = self.uInt32
        self.written = self.int32
        self.read = self.int32()

    
def ErrorCheck(dll, err):
    """a simple error checking routine"""
    if err < 0:
        buf_size = 100
        buf = ctypes.create_string_buffer('\000' * buf_size)
        dll.DAQmxGetErrorString(err, ctypes.byref(buf), buf_size)
        raise RuntimeError('Call failed with error %d: %s'%(err, repr(buf.value)))

def CreateTask(dll, types, task) :
    task_handle = types.task_handle(task)
    ErrorCheck(dll, dll.DAQmxCreateTask("",ctypes.byref(task_handle)))
    return task_handle

def StartTask(dll, task_handle) :
    ErrorCheck(dll,dll.DAQmxStartTask(task_handle))

def EndTask(dll, task_handle) :
    dll.DAQmxStopTask(task_handle)

def ClearTask(dll, task_handle) :
    dll.DAQmxClearTask(task_handle)


def Test() :
    dll, message = LoadDLL()    # Establish a handle to the dll
    if dll == 0 :
        print 'Library not loadable.  ' + message
        sys.exit()
    t = Types()                         # Define some recognizable data types.
    th = CreateTask(dll, t, 0)    # Create the handle for task 0.
    StartTask(dll, th)

#----------------------------------------------------------------------------------------------------------------------------------------------------

if __name__ == '__main__' :
    Test()