switch (pData->pWorkrow[0])
switch (*(pData->pWorkrow + pData->iFilterofs))
mng_retcode filter_a_row (mng_datap pData){  mng_retcode iRetcode;#ifdef MNG_SUPPORT_TRACE  MNG_TRACE (pData, MNG_FN_FILTER_A_ROW, MNG_LC_START)#endif  switch (pData->pWorkrow[0])  {    case 1  : {                iRetcode = filter_sub     (pData);                break;              }    case 2  : {                iRetcode = filter_up      (pData);                break;              }    case 3  : {                iRetcode = filter_average (pData);                break;              }    case 4  : {                iRetcode = filter_paeth   (pData);                break;              }    default : iRetcode = MNG_INVALIDFILTER;  }#ifdef MNG_SUPPORT_TRACE  MNG_TRACE (pData, MNG_FN_FILTER_A_ROW, MNG_LC_END)#endif  return iRetcode;}