Adaptec 1737100 Programmer Manual - Page 185

Sample Driver Transmit Handling In the code fragment below, the operating system has called the transmit routine with a packet to be transmitted. The driver must set up the Transmit Buffer Descriptor(s) for all buffers in this packet, and then instruct the AIC-6915 controller to transmit the packet. Example: // Windows NT driver example // Type 1 Transmit Buffer Descriptor // Single Transmit Buffer Descriptor Queue (low priority) // 8 byte skip field // Assume the operating system has notified us that we are to transmit // "Packet" // Read in the current producer index register AIC6915_READ_REG(Adapter->RegisterBaseVa->TxDescQProducerIndex, &TxDescQProducerIndexValue); // Pull the current descriptor index out of the producer index. The producer // index points to the next entry in the descriptor queue in units of 8 // bytes.In this example, we are using // Type 1 descriptors with an 8 byte skip field. The descriptor size is // therefore 16 bytes. In // units of 8 bytes, each descriptor is indexed by 2. CurrentTxDescIndex = (TxDescQProducerIndexValue.LoPrTxProducerIndex * 8) / sizeof(TransmitBufferDescriptor); // Get the first buffer in this packet // This is an operating system-specific call NdisQueryPacket( Packet, &PhysicalSegmentCount, &NdisBufferCount, &CurrentBuffer, &TotalDataLength); FirstBuffer = TRUE; // Figure out if we will need to roll the queue for this packet if (CurrentTxDescIndex+PhysicalSegmentCount >=AIC6915_NUMBER_0F_TxDESC-1) Rollover = TRUE; // Loop over all buffers in this packet. Use one Transmit Buffer per packet // buffer. // while (CurrentBuffer) { // This example utilizes map registers to translate the logical address // into a physical buffer address // Get the physical address segments for the current buffer NdisMStartBufferPhysicalMapping( Adapter->MiniportAdapterHandle, CurrentBuffer, 8-25