[example] Update library example

Author: kostorr

src/Example.cxx

@@ -9,90 +9,32 @@
 // or submit itself to any jurisdiction.
 
 /// \file Example.cxx
-/// \brief Example of pushing pages with the ReadoutCard C++ interface
+/// \brief Example usage of the BAR interface
 ///
-/// \author Pascal Boeschoten (pascal.boeschoten@cern.ch)
+/// \author Kostas Alexopoulos (kostas.alexopoulos@cern.ch)
 
 #include <iostream>
-#include <chrono>
-#include <thread>
-#include <boost/exception/diagnostic_information.hpp>
 #include "ReadoutCard/ChannelFactory.h"
-#include "ReadoutCard/Exception.h"
-#include "ReadoutCard/MemoryMappedFile.h"
 
-using std::cout;
-using std::endl;
 using namespace o2;
 
-int main(int, char**)
+int main()
 {
-  try {
-
-    // Get the DMA channel object
-    cout << "\n### Acquiring DMA channel object" << endl;
-
-    // Create a 10MiB file in 2MiB hugepage filesystem
-    constexpr size_t superpageSize = 2 * 1024 * 1024;
-    constexpr size_t superpageCount = 5;
-    constexpr size_t bufferSize = superpageCount * superpageSize;
-    roc::MemoryMappedFile file{ "/dev/hugepages/rorc_example.bin", bufferSize };
-
-    // Create parameters object for channel
-    auto parameters = roc::Parameters()
-                        .setCardId(roc::SerialId{ -1, 0 })                                                     // Dummy card
-                        .setChannelNumber(0)                                                                   // DMA channel 0
-                        .setBufferParameters(roc::buffer_parameters::Memory{ file.getAddress(), bufferSize }); // Register our buffer
-
-    // Get the DMA channel
-    std::shared_ptr<roc::DmaChannelInterface> channel = roc::ChannelFactory().getDmaChannel(parameters);
-
-    // Start the DMA
-    cout << "\n### Starting DMA" << endl;
-    channel->startDma();
-
-    // Keep track of time, so we don't wait forever for pages to arrive if things break
-    const auto start = std::chrono::steady_clock::now();
-    auto timeExceeded = [&]() { return ((std::chrono::steady_clock::now() - start) > std::chrono::seconds(5)); };
-
-    cout << "### Pushing pages" << endl;
-
-    // Queue up some superpages
-    for (size_t i = 0; i < superpageCount; ++i) {
-      auto offset = i * superpageSize;
-      auto size = superpageSize;
-      channel->pushSuperpage(roc::Superpage(offset, size));
-      cout << "Pushed superpage " << i << '\n';
-    }
-
-    while (true) {
-      if (timeExceeded()) {
-        cout << "Time was exceeded!\n";
-        break;
-      }
-      if (channel->getReadyQueueSize() == 0) {
-        cout << "Done!\n";
-        break;
-      }
-
-      // Does internal driver business, filling up superpages
-      channel->fillSuperpages();
-
-      // Get superpage at front of queue
-      auto superpage = channel->getSuperpage();
-      if (superpage.isReady()) {
-        channel->popSuperpage();
-        cout << "Superpage " << (superpage.getOffset() / superpageSize) << " arrived\n";
-      }
-
-      // Give the CPU some resting time
-      std::this_thread::sleep_for(std::chrono::milliseconds(1));
-    }
-  } catch (const std::exception& e) {
-    // Most exceptions thrown from the library inherit from boost::exception and will contain information besides
-    // the "what()" message that can help diagnose the problem. Here we print this information for the user.
-    cout << boost::diagnostic_information(e) << endl;
+  // See https://github.com/AliceO2Group/ReadoutCard#addressing for other addressing options
+  auto parameters = roc::Parameters()
+                      .setCardId(roc::PciSequenceNumber{ "#1" })
+                      .setChannelNumber(2); // BAR numbre, Should always be 2
+  auto bar = o2::roc::ChannelFactory().getBar(parameters);
+
+  uint32_t address = 0x00260004;
+
+  bar->writeRegister(address / 4, 0x42);
+  auto reg = bar->readRegister(address / 4);
+  if (reg == 0x42) {
+    std::cout << "SUCCESS" << std::endl;
+    return 0;
   }
 
-  return 0;
+  std::cout << "FAILURE" << std::endl;
+  return 1;
 }