readCdfQc <- function(filename, units = NULL, verbose = 0){
  filename <- file.path(dirname(filename), basename(filename))
  if (!file.exists(filename))
    stop("file:", filename, "does not exist.")

  returnIndices <- TRUE;
  returnXY <- TRUE;
  returnLength <- TRUE;
  returnPMInfo <- TRUE;
  returnBackgroundInfo <- TRUE;
  returnType <- TRUE;
  returnQcNumbers <- TRUE;

  # UNSUPPORTED CASE?
  if (!is.null(units) && length(units) == 0L) {
    stop("readCdfQc(..., units=integer(0)) is not supported.")
  }

  res <- .Call("R_affx_get_cdf_file_qc",
                filename, as.integer(units), as.integer(verbose),
                returnIndices, returnXY, returnLength, returnPMInfo,
                returnBackgroundInfo, returnType, returnQcNumbers);

  # Sanity check
  if (is.null(res)) {
    stop("Failed to read QC units from CDF file: ", filename);
  }

  res;
} # readCdfQc()


############################################################################
# HISTORY:
# 2011-11-18
# o ROBUSTNESS: Added sanity check that the native code did not return NULL.
############################################################################