session.py 文件源码

def fetch_waveform_into(self, waveform_data):
        '''fetch_waveform

        Returns waveform data.

        Args:
            waveform_data (numpy array of float64): Samples fetched from the device. Array should be numberOfSamples big.

        Returns:
            waveform_data (numpy array of float64): Samples fetched from the device. Array should be numberOfSamples big.
            actual_number_of_samples (int): Number of samples actually fetched.
        '''
        import numpy

        if type(waveform_data) is not numpy.ndarray:
            raise TypeError('waveform_data must be {0}, is {1}'.format(numpy.ndarray, type(waveform_data)))
        if numpy.isfortran(waveform_data) is True:
            raise TypeError('waveform_data must be in C-order')
        if waveform_data.dtype is not numpy.dtype('float64'):
            raise TypeError('waveform_data must be numpy.ndarray of dtype=float64, is ' + str(waveform_data.dtype))
        number_of_samples = len(waveform_data)

        vi_ctype = visatype.ViSession(self._vi)  # case 1
        number_of_samples_ctype = visatype.ViInt32(number_of_samples)  # case 8
        waveform_data_ctype = numpy.ctypeslib.as_ctypes(waveform_data)  # case 13.5
        actual_number_of_samples_ctype = visatype.ViInt32()  # case 14
        error_code = self._library.niFake_FetchWaveform(vi_ctype, number_of_samples_ctype, waveform_data_ctype, ctypes.pointer(actual_number_of_samples_ctype))
        errors.handle_error(self, error_code, ignore_warnings=False, is_error_handling=False)
        return