pWorkrow = pData->pWorkrow + 1;
pWorkrow = pData->pWorkrow + pData->iPixelofs;
mng_retcode store_jpeg_rgb8_a1 (mng_datap pData){  mng_imagedatap pBuf = (mng_imagedatap)pData->pStorebuf;  mng_uint8p     pWorkrow;  mng_uint8p     pOutrow;  mng_int32      iX;  mng_uint8      iB;  mng_uint8      iM;#ifdef MNG_SUPPORT_TRACE  MNG_TRACE (pData, MNG_FN_STORE_JPEG_RGB8_A1, MNG_LC_START)#endif  pWorkrow = pData->pWorkrow + 1;      /* temporary work pointers */  pOutrow  = pBuf->pImgdata + (pData->iRow * pBuf->iRowsize   ) +                              (pData->iCol * pBuf->iSamplesize) + 3;  iM       = 0;                        /* start at pixel 0 */  iB       = 0;  for (iX = 0; iX < pData->iRowsamples; iX++)  {    if (!iM)                           /* mask underflow ? */    {      iB = *pWorkrow;                  /* get next input-byte */      pWorkrow++;      iM = 0x80;    }    if (iB & iM)                       /* is it opaque ? */      *pOutrow = 0xFF;                 /* opaque */    else      *pOutrow = 0x00;                 /* transparent */    pOutrow += 4;                      /* next pixel */    iM >>= 1;  }#ifdef MNG_SUPPORT_TRACE  MNG_TRACE (pData, MNG_FN_STORE_JPEG_RGB8_A1, MNG_LC_END)#endif  return next_jpeg_alpharow (pData);   /* we've got one more row of alpha-samples */}