basic implementatio to handle barcode_field in feeds module

mekit_barcode_feeds_processor.module

<?php


/**
 * Enable barcode field handling for Feeds
 *
 * Implements hook_feeds_processor_targets_alter().
 * @param array  &$targets
 *   Array containing the targets to be offered to the user. Add to this array
 *   to expose additional options.
 * @param string $entity_type
 *   The entity type of the target, for instance a 'node' entity.
 * @param string $bundle
 *   The entity bundle to return targets for.
 */
function mekit_barcode_feeds_processor_feeds_processor_targets_alter(array &$targets, $entity_type, $bundle) {
  foreach (field_info_instances($entity_type, $bundle) as $fieldName => $fieldInstance) {
    $fieldInfo = field_info_field($fieldName);
    if ($fieldInfo['type'] == 'barcode_field') {
      $targets[$fieldName] = [
        'name' => check_plain($fieldInstance["label"]),
        'callback' => 'mekit_barcode_feeds_processor_target',
        'description' => t('The @label field of the node.', array('@label' => $fieldInstance['label'])),
      ];
    }
  }
}

/**
 * Handle how to import data
 *
 * @param \FeedsSource $source
 * @param \stdClass    $entity
 * @param string       $target
 * @param array        $values
 * @param array        $mapping
 */
function mekit_barcode_feeds_processor_target(\FeedsSource $source, $entity, $target, array $values, array $mapping) {
  $field_name = $target;
  $field = isset($entity->$field_name) ? $entity->$field_name : ['und' => []];
  $fieldInfo = field_info_field($field_name);

  // Iterate over all values.
  $delta = 0;
  foreach ($values as $value) {
    //do validation here
    $field[LANGUAGE_NONE][$delta]['value'] = $value;
    $delta++;
  }

  $entity->$field_name = $field;
}