Manuals / Compaq / Computer Equipment / Network Card

Compaq AA-RNG2A-TE manual Discarding a Packet

Models: AA-RNG2A-TE

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eh = *(mtod(m, struct ether_header *)); 2

eh.ether_type = ntohs((unsigned short)eh.ether_type); m->m_data += sizeof(struct ether_header); 4

ADD_RECV_PACKET(ifp, sc, m->m_pkthdr.len); 5 if (eh.ether_dhost[0] & 0x1) {

ADD_RECV_MPACKET(ifp, sc, m->m_pkthdr.len);

}

i = READ_RXS(sc); 6 if (i &= 0x7ff) {

if ((i & 0x400) == 0) { m_freem(m);

goto scrap;

}

}

ether_input(ifp, &eh, m); 7

}

}

3

1Calls the io_blockread( ) routine to perform the data transfer from the FIFO buffer on the adapter to the mbuf in host memory.

2Makes a copy of the ether_header data structure for the ether_input( ) routine.

3Converts the 2-byte ether_type field from network byte order to host byte order and saves it in the ether_header data structure.

4Adjusts the pointer to the received data to point past the MAC header (skips past the destination address, source address, and ether_type fields).

5Calls the ADD_RECV_PACKET macro to increment the receive packet (block) count. If this packet was destined for a broadcast or multicast address, calls the ADD_RECV_MPACKET macro to increment those statistics as well.

6Calls the READ_RXS macro to read the receive status. If the packet just received was not fully received, scraps the packet.

7Calls the ether_input( ) routine to process the received Ethernet packet. The packet is in the mbuf chain without the ether_header data structure, which is provided separately.

13.2.5Discarding a Packet

The following code shows how the el_rint( ) routine discards a packet. Some receive interrupt handlers perform a copy of a few bytes of the packet to determine if the packet is actually destined for the device. Thus, this task is an optional optimization.

scrap:

WRITE_CMD(sc, CMD_RXDTP); status = READ_RXS(sc);

}

1

Implementing the Interrupt Section 13–9

Image 147

Compaq AA-RNG2A-TE manual Discarding a Packet

Contents

Compaq Computer Corporation Houston, Texas December Product VersionPage Contents Implementing the Autoconfiguration Support Section probe Implementing the Configure SectionImplementing the unattach Routine Implementing the Autoconfiguration Support Section attachImplementing the Start Section Implementing the Initialization SectionImplementing the Reset Section Implementing a Watchdog SectionImplementing the ioctl Section Implementing the Interrupt Section Network Device Driver Configuration IndexTables Page Audience About This ManualScope of this Manual Organization New and Changed FeaturesExamples Related DocumentationReference Pages Reader’s CommentsConventions That are used in driver configuration, these brackets Page Network Device Driver Environment Network Device Driver Include Files Section for a Network Driver Declarations Section for a Network Driver External and Forward Declarations Declaring softc and controller Data Structure Arrays Defining Driver-Specific Macros Declaring and Initializing the driver Data Structure8Network Device Driver Environment MacroDescription Driver-Specific MacrosStart Section for a Network Driver Configure Section for a Network DriverAutoconfiguration Support Section for a Network Driver Initialization Section for a Network DriverInterrupt Section for a Network Driver Reset Section for a Network DriverWatchdog Section for a Network Driver Ioctl Section for a Network Driver12Network Device Driver Environment Interrupt and Status Register Offset Definitions Defining Device Register OffsetsCommand Port Register Offset Definitions Defining Device Register Offsets Window 0 Configuration Register Offset Definitions W0CCR Register ConstantDefines the offset for the resource configuration register Window 3 Configuration Register Offset Definitions Window 3 Configuration Registers Window 1 Operational Registers Window 1 Operational Register Offset Definitions10Defining Device Register Offsets Mdncrc Window 4 Diagnostic Register Offset Definitions12Defining Device Register Offsets Eeprom Data Structure Definition Page Shows a typical softc data structure Defining the softc Data Structure2Defining the softc Data Structure Defining Common InformationDefining the softc Data Structure Defining Media State Information Enabling Support for Enhanced Hardware ManagementMedia state has been determined Defining CSR Pointer Information Defining the Base RegisterDefining Multicast Table Information Defining the Interrupt Handler IDDefining Bus-Specific Information Defining Fifo Maintenance InformationDefining Interrupt and Timeout Statistics Defining the Broadcast FlagDefining the Debug Flag Defining the Polling Context Flag Defining Autosense Kernel Thread Context InformationDeclaring the Simple Lock Data Structure Defining a Copy of the w3eeprom Data StructureImplementing the Configure Section Etc/sysconfigtab database Following code shows how to set up the elconfigure routine Setting Up the elconfigure Routine4Implementing the Configure Section Implementing the elprobe Routine Implementing the Autoconfiguration Support Section probeFollowing code shows how to set up the elprobe routine Setting Up the elprobe RoutineImplementing the Autoconfiguration Support Section probe Performing Bus-Specific Tasks 4Implementing the Autoconfiguration Support Section probeImplementing the Autoconfiguration Support Section probe Allocating Memory for the softc Data Structure 6Implementing the Autoconfiguration Support Section probeAllocating the etherdriver Data Structure Computing the CSR Addresses Setting Bus-Specific Data Structure MembersImplementing the Autoconfiguration Support Section probe Handling First-Time Probe Operations 10Implementing the Autoconfiguration Support Section probeImplementing the Autoconfiguration Support Section probe Handling Subsequent Probe Operations 12Implementing the Autoconfiguration Support Section probeImplementing the Autoconfiguration Support Section probe Registering the Interrupt Handler Implementing the Autoconfiguration Support Section probe Trying to Allocate Another controller Data Structure Saving the controller and softc Data Structure PointersImplementing the elshutdown Routine Implementing the elautosensethread RoutineRegistering the shutdown Routine 18Implementing the Autoconfiguration Support Section probe Blocking Until Awakened Setting Up the elautosensethread RoutineTesting for the Termination Flag Starting Up StatisticsEntering the Packet Transmit Loop Using the Default from the ROM Saving Counters Prior to the Transmit OperationAllocating Memory for a Test Packet Setting the Media in the Hardware Building the Test PacketTransmitting the Test Packet Testing for Loss of Carrier Setting a Timer for the Current Kernel ThreadSetting Up New Media Determining Whether Packets Were Transmitted SuccessfullyPrinting Debug Information Establishing the Media 26Implementing the Autoconfiguration Support Section probe Setting Up the elattach Routine Implementing the Autoconfiguration Support Section attachInitializing the Media Address and Media Header Lengths Setting Up the Media 4Implementing the Autoconfiguration Support Section attach Initializing Simple Lock Information Specifying the Network Driver Interfaces Printing a Success MessageSignifies that the network interface supports Attaching to the Packet Filter and the Network Layer Setting the Baud RateHandling the Reinsert Operation Setting Network Attributes and Registering the AdapterStarting the Polling Process Enabling the Interrupt HandlerImplementing the unattach Routine Setting Up the elunattach RoutineObtaining the Simple Lock and Shutting Down the Device Verifying That the Interface Has Shut DownTerminating the Autosense Kernel Thread Disabling the Interrupt HandlerTerminating the Simple Lock Unregistering the Pcmcia Event Callback RoutineStopping the Polling Process Unregistering the Shutdown RoutineFreeing Resources Unregistering the Card from the Hardware Management DatabasePage Setting Up the elinit Routine Implementing the Initialization SectionImplementing the elinit Routine Determining Whether the Pcmcia Card Is Present Setting the IPL and Obtaining the Simple LockReturning the Status from the elinitlocked Routine Releasing the Simple Lock and Resetting the IPLImplementing the elinitlocked Routine Calling the elinitlocked RoutineClearing Interrupts Resetting the Transmitter and ReceiverEnsuring That the 10Base2 Transceiver Is Off Starting the DeviceSetting the LAN Media Setting a LAN Attribute Resetting the Transmitter and Receiver AgainSelecting Memory Mapping Processing Special Flags Setting the LAN AddressEnabling TX and RX Setting the Debug FlagSetting the Operational Window Enabling InterruptsMarking the Device as Running Starting the Transmit of Pending Packets Starting the Autosense Kernel ThreadPage Implementing the elstart Routine Implementing the Start SectionCalling the elstartlocked Routine Implementing the elstartlocked Routine 4Implementing the Start Section Implementing the Start Section Handlelongword Transmitting the BufferAccounting for Outgoing Bytes Indicating When to Start the Watchdog Routine Implementing a Watchdog Section Setting the IPL and Obtaining the Simple LockReleasing the Simple Lock and Resetting the IPL Implementing the elreset Routine Implementing the Reset SectionImplementing the elresetlocked Routine Implementing the ioctl Section Ioctl Command Required Description For More InformationFollowing code shows how to set up the elioctl routine Setting Up the elioctl RoutineSetting the IPL and Obtaining the Simple Lock Disabling Loopback Mode Siocdisablback ioctl Command Enabling Loopback Mode Siocenablback ioctl CommandSetting the Local MAC Address Siocsphysaddr ioctl Command 12-6Implementing the ioctl Section Implementing the ioctl Section Determines whether the cmd argument is Siocrdctrs or Network Interface Counter Types Bringing Up the Device Siocsifaddr ioctl CommandUsing Currently Set Flags Siocsifflags ioctl Command Setting the IP MTU Siocsipmtu ioctl CommandSetting the Media Speed Siocsmacspeed ioctl Command Setting Device Characteristics Siocifsetchar ioctl Command Resetting the Device Siocifreset ioctl Command12-12Implementing the ioctl Section If lockon 1 simpleunlock&sc-elsoftclock splxs Return status Page Implementing the elintr Routine Implementing the Interrupt SectionRearming the Next Timeout Processing Completed Receive and Transmit Operations Reading the Interrupt StatusTransmitting Pending Frames Acknowledging the InterruptImplementing the elrint Routine Indicating That the Interrupt Was ServicedPulling the Packets from the Fifo Buffer Examining the First Part of the Packet 13-8Implementing the Interrupt Section Copying the Received Packet into the mbufDiscarding a Packet Counting the Transmit Interrupt Implementing the eltint RoutineWriting to the Status Register to Obtain the Next Value Managing Excessive Data CollisionsQueuing Other Transmits Implementing the elerror RoutineNetwork Device Driver Configuration Page Index-1 IndexIndex-2 Declarations section, 1-4devdriver.h header file, 1-4deviceIndex-3 InterruptIndex-4 Interrupt handlerIndex-5 PacketIndex-6 ROMIndex-7 Transmit