transmit_on_timestamp_setclock_example.c Source File

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/**
 * @example net/transmit_on_timestamp_setclock/transmit_on_timestamp_setclock_example.c
 * @section transmit_on_timestamp_setclock_example_description Description
 *
 * This source file is an example of how to transmit a sequence of packets
 * on timestamp multiple times, but instead of manually reconfiguring the
 * delta for each iteration, TXSETCLOCK is used to advance the delta with
 * the duration of a single replay iteration. An example application of this
 * functionality would be where one wishes to replay a single capture file
 * multiple times.
 *
 * This example will transmit 100000 packets of 296 bytes from port 0 at a rate
 * of approximately 5 Mb/s. The packet contains an incrementing 32bit pattern.
 *
 * The transmit on timestamp functionality is also available in segment mode.
 * See the @ref net/transmit_segment/transmit_segment_example.c example code
 * to see how to use the segment interface.
 *
 * The following NTAPI functions are used:
 * - @ref NT_Init()
 * - @ref NT_ConfigOpen()
 * - @ref NT_ConfigRead()
 * - @ref NT_ConfigWrite()
 * - @ref NT_ConfigClose()
 * - @ref NT_NetTxOpen_v2()
 * - @ref NT_NetTxGet()
 *   - @ref NT_NET_SET_PKT_TIMESTAMP()
 *   - @ref NT_NET_SET_PKT_TXSETCLOCK()
 *   - @ref NT_NET_GET_PKT_L2_PTR()
 * - @ref NT_NetTxRelease()
 * - @ref NT_NetTxClose()
 * - @ref NT_Done()
 * - @ref NT_ExplainError()
 *
 * @section transmit_on_timestamp_setclock_example_prerequisites Prerequisites
 * - This example is only compatible with adapters supporting 4GA transmit on
 *   timestamp.
 * - The ntservice.ini must have at least one HostBuffersTx defined. Below is
 * an example of a minimum ini-file. It will create a 4MB TX hostbuffer from
 * NUMA node 0.
 *
 * @code
 * [Adapter0]
 * AdapterType     = NT20E2
 * BusId           = 00:0a:00.00
 * HostBuffersTx   = [1,4,0]
 * @endcode
 *
 * @section transmit_on_timestamp_setclock_example_flow Program flow
 * @{
 * The following is required to transmit packages:
 * - \#include/nt.h - Applications/Tools only need to include @ref
 *   nt.h to obtain prototypes, macros etc. from NTAPI.
 * - @ref NT_Init(@ref NTAPI_VERSION) - Initialize the NTAPI
 *   library. @ref NTAPI_VERSION is a define that describes the version
 *   of the API described in the header files included by @ref
 *   nt.h. NT_Init() will ask the NTAPI library to convert return data
 *   to the @ref NTAPI_VERSION if possible. This will ensure that
 *   applications can run on NTAPI libraries of newer versions.
 * - @ref NT_ConfigOpen() - Open the config stream.
 * - @ref NT_ConfigRead() - Use the config stream to read the current adapter
 *   time.
 * - @ref NT_ConfigWrite() - Use the config stream to configure transmit on
 *   timestamp, using the retrieved adapter time.
 * - @ref NT_NetTxOpen() - Open a hostbuffer than can transmit packets to port 0.
 * - @ref NT_NetTxOpen_v2() - Open a hostbuffer than can transmit packets to port 0.
 * - @ref NT_NetTxGet() - Get an empty tx buffer. This will get a 296 byte
 *   wire length packet buffer that will be sent onto port 0 when the packet
 *   buffer is released, and the timestamp has been reached on the adapter.
 *   - @ref NT_NET_GET_PKT_L2_PTR() is used to get the L2 pointer to the tx
 *     buffer, this is where the payload is placed.
 *   - @ref NT_NET_SET_PKT_TXSETCLOCK() is used to enable txsetclock on the
 *     first packet in the replay sequence.
 *   - @ref NT_NET_SET_PKT_TIMESTAMP() is used to set the timestamp of the
 *     packet
 * - @ref NT_NetTxRelease() - Release the tx packet buffer. Once a tx
 *   buffer is released it will be transmitted
 * - @ref NT_ConfigRead() - Read the adapter timestamp to check if the last
 *   packet should have been transmitted. We need to do this in order to avoid
 *   disabling transmit on timestamp too early.
 * - @ref NT_ConfigWrite() - Disable transmit on timestamp.
 * - @ref NT_ConfigClose() - Close the configuration stream.
 * - @ref NT_NetTxClose() - Close the TX stream.
 * - @ref NT_Done() - Close down the NTAPI library.
 *
 *<hr>
 * @section transmit_on_timestamp_setclock_example_code Code
 * @}
 */

// Include this in order to access the Napatech API
#include <nt.h>

#if defined(__linux__) || defined(__FreeBSD__) || (__MINGW32__)
  #include <unistd.h> // sleep()
#endif

#if defined(_MSC_VER)
  #include <timesupport.h>
#endif

#include <assert.h>

#define PACKETS     100L        // How many packets to send
#define PACKET_SIZE 296L        // Packet size to transmit (incl crc.)
#define PACKET_GAP  500000L     // Distance in 1ns between packets
#define REPLAYS     1000L       // How many times we will repeat the packets
#define TX_DELAY    1000000000  // Initial transmission delay (one second)
#define PORT        0
#define ADAPTER     0

// This program, by default, uses the NT descriptor type to transmit packets.
// To use a PCAP descriptor, set the boolean variable pcapPackets to true.
bool pcapPackets = false; // Set to true to enable PCAP descriptor type.

// Time in nanoseconds to transmit one replay session
#define REPLAY_TRANSMIT_TIME (PACKET_GAP * PACKETS)

// Time in nanoseconds to transmit all replay sessions
#define TOTAL_TRANSMIT_TIME (REPLAY_TRANSMIT_TIME * REPLAYS)

// Struct pcap_timespec_s is the time specification for PCAP. For PCAP_NANO,
// the ts_usec field is in nanoseconds instead of microseconds.
struct pcap_timespec_s {
  uint32_t ts_sec;
  uint32_t ts_usec;
};

// Standard PCAP record header.
struct pcap_record_s {
  struct pcap_timespec_s time;
  uint32_t incl_len;
  uint32_t orig_len;
};

// printError is a simple convenience function for printing an NTAPI error
// message to stderr.
static void printError(const char *prefix, int errorCode) {
  char errorBuffer[NT_ERRBUF_SIZE];
  NT_ExplainError(errorCode, errorBuffer, sizeof errorBuffer);
  fprintf(stderr, "%s: %s\n", prefix, errorBuffer);
}

static uint64_t
convertToUnixNsTs(const struct NtConfigTimestampReadData_s *data)
{
  const struct pcap_timespec_s *pcap_ts = (const struct pcap_timespec_s *)&data->ts;
  switch (data->tsType) {
  case NT_TIMESTAMP_TYPE_PCAP_NANOTIME:
    return pcap_ts->ts_sec * 1000000000ULL + pcap_ts->ts_usec;
  case NT_TIMESTAMP_TYPE_UNIX_NANOTIME:
    return data->ts;
  default:
    // default to nativeUnixTs when nanosecond resolution unavailable
    // this is Unix Time with 10ns resolution.
    return data->nativeUnixTs * 10;
  }
}

int main(void)
{
  //
  // Initialize the API. This also checks if we are compatible with the
  // installed library version.
  //
  int status;

  if ((status = NT_Init(NTAPI_VERSION)) != NT_SUCCESS) {
    printError("NT_Init() failed", status);
    return -1;
  }

  //
  // Open the config stream, in order to retrieve the adapter timestamp and
  // to configure the transmit on timestamp functionality. We configure
  // transmit on timestamp in such a way that a packet with timestamp 0 will
  // transmit in approximately one second from this point.
  //
  NtConfigStream_t hConfig;
  NtConfig_t config;

  if ((status = NT_ConfigOpen(&hConfig, "replay")) != NT_SUCCESS) {
    printError("NT_ConfigOpen() failed", status);
    return -1;
  }

  config.parm = NT_CONFIG_PARM_ADAPTER_TIMESTAMP;
  config.u.timestampRead.adapter = ADAPTER;

  if ((status = NT_ConfigRead(hConfig, &config)) != NT_SUCCESS) {
    printError("NT_ConfigRead() failed", status);
    return -1;
  }

  // Store the adapter timestamp and convert it to unix nanoseconds.
  // Nanosecond precision is only available if TimestampFormat = UNIX_NS or
  // TimestampFormat = PCAP_NS as defined in ntservice.ini.
  // If TimestampFormat is set to anything else, it will derive the
  // nanosecond timestamp from the NATIVE timestamp, which is measured
  // in 10-ns ticks, and hence lose a small amount of precision.
  uint64_t adapterTS = convertToUnixNsTs(&config.u.timestampRead.data);

  // Configure transmit on timestamp. In scenarios where a packet descriptor
  // that does not contain a TXNOW bit is used, such as when transmitting PCAP,
  // forceTxOnTs must be set to true. However, this example uses NT
  // descriptors, and can thus use the TXNOW bit.
  //
  // timeDeltaAdjust is set to the time it takes to complete a single replay
  // session, so that the TXSETCLOCK bit will cause timeDelta to be prepared
  // for the next replay run. Note that since we set TXSETCLOCK on the first
  // packet of every iteration, including the first one, that the value of
  // timeDeltaAdjust need to be subtracted from timeDelta to avoid accidentally
  // delaying the initial transmission.
  // There must be "room" for one replay session within the delay window.
  const uint64_t txBeginTS = adapterTS + TX_DELAY;
  config.parm = NT_CONFIG_PARM_PORT_TRANSMIT_ON_TIMESTAMP;
  config.u.transmitOnTimestamp.portNo = (uint8_t)PORT;
  assert(txBeginTS >= REPLAY_TRANSMIT_TIME);
  config.u.transmitOnTimestamp.data.timeDelta = txBeginTS - REPLAY_TRANSMIT_TIME;
  config.u.transmitOnTimestamp.data.timeDeltaAdjust = REPLAY_TRANSMIT_TIME;
  config.u.transmitOnTimestamp.data.enable = true;
  if (pcapPackets) {
    // PCAP descriptor
    config.u.transmitOnTimestamp.data.forceTxOnTs = true;
  }  else {
    // NT descriptor
    config.u.transmitOnTimestamp.data.forceTxOnTs = false;
  }

  if ((status = NT_ConfigWrite(hConfig, &config)) != NT_SUCCESS) {
    printError("NT_ConfigWrite() failed", status);
    return -1;
  }

  //
  // Open a TX stream
  //
  NtNetStreamTx_t hNetTx;
  if ((status = NT_NetTxOpen_v2(
         &hNetTx, "transmit_on_timestamp_example_txstream", 1ULL << PORT,
         NT_NETTX_NUMA_ANY_HB, 0,
         pcapPackets ? NT_PACKET_DESCRIPTOR_TYPE_PCAP : NT_PACKET_DESCRIPTOR_TYPE_NT,
         pcapPackets ? NT_TIMESTAMP_TYPE_PCAP_NANOTIME : NT_TIMESTAMP_TYPE_UNIX_NANOTIME)) != NT_SUCCESS) {
    printError("NT_NetTxOpen_v2() failed", status);
    return -1;
  }

  //
  // Retrieve a packet buffer, fill it, and repeat until we have transmitted
  // the requested amount of packets. The timestamp will be set so that the
  // adapter will transmit at approximately 5 Mb/s.
  //
  printf("Commencing transmission of %ld packets %ld times\n", PACKETS, REPLAYS);

  NtNetBuf_t hNetBufTx;
  int totalPackets = 0;

  for (int replays = 0; replays < REPLAYS; replays++) {

    uint64_t timestamp = 0;
    for (int pkts = 0; pkts < PACKETS; pkts++, totalPackets++) {

      // Get a packet TX buffer for this tx stream and port, without timeout
      if ((status = NT_NetTxGet(hNetTx, &hNetBufTx, PORT, PACKET_SIZE,
              NT_NETTX_PACKET_OPTION_DEFAULT, -1)) != NT_SUCCESS) {
        printError("NT_NetTxGet() failed", status);
        return -1;
      }

      // Set the packet timestamp
      if (pcapPackets) {
        // PCAP descriptor
        struct pcap_record_s *hdr =
          (struct pcap_record_s *)NT_NET_GET_PKT_DESCR_PTR(hNetBufTx);
        hdr->incl_len = PACKET_SIZE;
        hdr->orig_len = PACKET_SIZE;
        hdr->time.ts_sec = (uint32_t)(timestamp / 1000000000U);
        hdr->time.ts_usec = (uint32_t)(timestamp % 1000000000U);
      } else {
        // NT descriptor
        NT_NET_SET_PKT_TIMESTAMP(hNetBufTx, timestamp);
      }

      timestamp += PACKET_GAP; // increment the timestamp for the next packet

      if (pkts == 0) {
        // We set TXSETCLOCK on the first packet. This results in the adapter
        // adding timeDeltaAdjust to timeDelta before transmitting this packet.
        NT_NET_SET_PKT_TXSETCLOCK(hNetBufTx, 1);
      }

      // Fill the packet with an incrementing payload. Note that this will result
      // in a garbage ethernet frame.
      uint32_t *ptr = (uint32_t*)NT_NET_GET_PKT_L2_PTR(hNetBufTx);
      for (uint32_t i = 0; i < PACKET_SIZE/4; i++) {
        *(ptr+i) = i;
      }

      // Release the TX buffer to commit the packet. It will transmit once the
      // timestamp is reached, or when transmit on timestamp is disabled.
      if ((status = NT_NetTxRelease(hNetTx, hNetBufTx)) != NT_SUCCESS) {
        printError("NT_NetTxRelease() failed", status);
        return -1;
      }
    }
  }

  //
  // Wait for all packets to be transmitted. There are multiple ways to do
  // this, but in this example, we read the adapter timestamp in a loop, and
  // compare it to the value of our timestamp variable from the loop above.
  //
  printf("Waiting for transmission to end\n");

  config.parm = NT_CONFIG_PARM_ADAPTER_TIMESTAMP;
  config.u.timestampRead.adapter = ADAPTER;

  const uint64_t txStopTS = txBeginTS + TOTAL_TRANSMIT_TIME;
  uint64_t newAdapterTS;
  do {
    sleep(1);
    if ((status = NT_ConfigRead(hConfig, &config)) != NT_SUCCESS) {
      printError("NT_ConfigRead() failed", status);
      return -1;
    }

    newAdapterTS = convertToUnixNsTs(&config.u.timestampRead.data);
  } while (newAdapterTS < txStopTS);

  //
  // Disable transmit on timestamp. If any packets are left in the buffera this
  // point, they will transmit unhindered at line rate.
  //
  config.parm = NT_CONFIG_PARM_PORT_TRANSMIT_ON_TIMESTAMP;
  config.u.transmitOnTimestamp.portNo = (uint8_t)PORT;
  config.u.transmitOnTimestamp.data.timeDelta = 0;
  config.u.transmitOnTimestamp.data.timeDeltaAdjust = 0;
  config.u.transmitOnTimestamp.data.enable = false;
  config.u.transmitOnTimestamp.data.forceTxOnTs = false;

  if ((status = NT_ConfigWrite(hConfig, &config)) != NT_SUCCESS) {
    printError("NT_ConfigWrite() failed", status);
    return -1;
  }

  //
  // Terminate
  //
  printf("Done: %d packets sent\n", totalPackets);

  //Close the Config stream
  NT_ConfigClose(hConfig);

  // Close the TX stream
  NT_NetTxClose(hNetTx);

  // Close the API
  NT_Done();

  return 0;
}