LwIp-Stack: Raw Ethernet Packete senden

uint32_t ETH_HandleTxPkt(uint8_t *ppkt, uint16_t FrameLength)

{ 

  uint32_t offset = 0;

  /* Check if the descriptor is owned by the ETHERNET DMA (when set) or CPU (when reset) */

  if((DMATxDescToSet->Status & ETH_DMATxDesc_OWN) != (uint32_t)RESET)

  {

    /* Return ERROR: OWN bit set */

    return ETH_ERROR;

  }

  /* Copy the frame to be sent into memory pointed by the current ETHERNET DMA Tx descriptor */      

  for(offset=0; offset<FrameLength; offset++)       

  {

    (*(__IO uint8_t *)((DMATxDescToSet->Buffer1Addr) + offset)) = (*(ppkt + offset));

  }

  /* Setting the Frame Length: bits[12:0] */

  DMATxDescToSet->ControlBufferSize = (FrameLength & ETH_DMATxDesc_TBS1);

  /* Setting the last segment and first segment bits (in this case a frame is transmitted in one descriptor) */    

  DMATxDescToSet->Status |= ETH_DMATxDesc_LS | ETH_DMATxDesc_FS;

  /* Set Own bit of the Tx descriptor Status: gives the buffer back to ETHERNET DMA */

  DMATxDescToSet->Status |= ETH_DMATxDesc_OWN;

  /* When Tx Buffer unavailable flag is set: clear it and resume transmission */

  if ((ETH->DMASR & ETH_DMASR_TBUS) != (uint32_t)RESET)

  {

    /* Clear TBUS ETHERNET DMA flag */

    ETH->DMASR = ETH_DMASR_TBUS;

    /* Resume DMA transmission*/

    ETH->DMATPDR = 0;

  }

  /* Update the ETHERNET DMA global Tx descriptor with next Tx decriptor */  

  /* Chained Mode */

  if((DMATxDescToSet->Status & ETH_DMATxDesc_TCH) != (uint32_t)RESET)

  {     

    /* Selects the next DMA Tx descriptor list for next buffer to send */ 

    DMATxDescToSet = (ETH_DMADESCTypeDef*) (DMATxDescToSet->Buffer2NextDescAddr);    

  }

  else /* Ring Mode */

  {  

    if((DMATxDescToSet->Status & ETH_DMATxDesc_TER) != (uint32_t)RESET)

    {

      /* Selects the first DMA Tx descriptor for next buffer to send: last Tx descriptor was used */

      DMATxDescToSet = (ETH_DMADESCTypeDef*) (ETH->DMATDLAR);      

    }

    else

    {  

      /* Selects the next DMA Tx descriptor list for next buffer to send */

      DMATxDescToSet = (ETH_DMADESCTypeDef*) ((uint32_t)DMATxDescToSet + 0x10 + ((ETH->DMABMR & ETH_DMABMR_DSL) >> 2));      

    }

  }

  /* Return SUCCESS */

  return ETH_SUCCESS;   

}