NIC Driver Outline

The basic driver outline below lists all of the main routines required for a NIC driver under RT-TCP/IP.

The DrvXmitThread routine is optional in some drivers, depending on implementation. If the driver requires that a packet be completed (transmitted) before the next packet is handed to the RtndTransmit routine, then a transmit thread which calls RtnTransmitDone after the transmit done interrupt will be required. RtnTransmitDone cannot be called from the transmit interrupt itself, since it will likely to invoke a deadlock between critical sections.

Example: RtxTcpIp Driver functions

#include "drvutl.h"
// Force the export of RTNDPROC functions
#define RTNDPROC __declspec ( dllexport )
#include "Rt3c905.h"
#include <stdio.h>
#include <stdlib.h>

int 
RtndInitialize (
      short* StackIniFile,
      char* pszSectionName,
      int fDisplayErrorMessages,
      char *DeviceName,
      RtndConfigStruct *RtCfg )
{
      // local configuration structure…
}

int
RtndConfigure (
      void *ndp )
{
      // Initialize NIC card. Start Receive thread and optionally
      // start transmit thread…
}

int
RtndUpDown (
      void *ndp,
      unsigned short flags,
      char *options )
{
      // Bring a NIC card online and attach interrupt vector,
      // or bring NIC down and release interrupt vector 
      //depending on flags parameter….
}

int
RtndIoctl (
      void *ndp,
      int cmd,
      char *addr )
{
      // Perform Device IO Control.
      //Used primarily to add or delete multicast groups.
}

int
RtndTransmit (
      void *mp )
{
      // Transmit a packet (or start transmit) via the NIC
}
static
ULONG
WINAPI
DrvRecvThread (
      DRVDEV* pCardInfo )
{
      // Process Received Packets. Notified by interrupt thread when
      // a packet has been received 
      for (;;)
      {
            WaitForSingleObject (pCardInfo->hRecvEvent, INFINITE);
            // pulls packets from card and queues them
            drv_RecvPackets (pCardInfo);
            // process the queued packets
            RtnProcessRecvQueue (pCardInfo->ndp);
      }
}

static
ULONG
WINAPI
DrvTransThread(
      DRVDEV* pCardInfo )
{
      // Post Process Transmitted Packets.
      //Notified by interrupt thread when a packet transmit is done.
      // This code calls RtnTransmitDone to free the most recently
      //transmitted packet and to start the next packet transmit,
      //if there is one.
      for (;;)
      {
            WaitForSingleObject (pCardInfo->hTransEvent, INFINITE);
            while (pCardInfo->XmitCount > 0)
            {
                  RtnTransmitDone (pCardInfo->ndp);
                  pCardInfo->XmitCount--;
            }// while
      }// for
}
static
void
WINAPI
DrvISR(
      DRVDEV* pCardInfo )
{
      // Interrupt Service Thread for driver. If a transmit or receive
      // interrupt fires, then signal the waiting transmit or
      // receive thread.

      // Do NOT call RtnTransmitDone from this routine.

      // If Transmit Interrupt then do the following:
      SetEvent(pCardInfo->hTransEvent);
      // If Receive Interrupt then do the following:
      SetEvent(pCardInfo->hRecvEvent);
}