[FUS-1598] Add C++ request_version example. (#270)

README.md

@@ -78,6 +78,8 @@ The `examples/` directory contains example applications demonstrating how to use
 - `external_cmake_project` - Download a copy of the FusionEngine Client library from the public repository and import
   it into a CMake project using `FetchContent`.
 - `generate_data` - Generate a binary file containing a fixed set of messages.
+- `lband_decode` - Example of decoding RTCM corrections from a recorded file containing LBandFrameMessage.
+- `request_version` - Simulate sending a request for a version info message, and waiting for a response.
 - `tcp_client` - Connect to a device over TCP and display the received FusionEngine messages.
 - `udp_client` - Connect to a device over UDP and display the received FusionEngine messages.
 

examples/BUILD

@@ -6,6 +6,7 @@ filegroup(
     srcs = [
         "//generate_data",
         "//message_decode",
+        "//request_version",
         "//tcp_client",
         "//udp_client",
     ]

examples/CMakeLists.txt

@@ -1,8 +1,9 @@
 add_subdirectory(common)
 
 add_subdirectory(generate_data)
-add_subdirectory(message_decode)
 add_subdirectory(lband_decode)
+add_subdirectory(message_decode)
+add_subdirectory(request_version)
 add_subdirectory(tcp_client)
 add_subdirectory(udp_client)
 

examples/common/print_message.cc

@@ -107,13 +107,35 @@ void PrintMessage(const MessageHeader& header, const void* payload_in) {
              sv.azimuth_deg);
       printf("    In solution: %s\n", sv.usage > 0 ? "yes" : "no");
     }
+  } else if (header.message_type == MessageType::VERSION_INFO) {
+    auto& contents = *reinterpret_cast<const VersionInfoMessage*>(payload);
+    payload += sizeof(contents);
+
+    double system_time = contents.system_time_ns * 1e-9;
+    printf(
+        "Version info message @ System time %.3f seconds. [sequence=%u, "
+        "size=%zu B]\n",
+        system_time, header.sequence_number, message_size);
+    printf("  Firmware version: %.*s\n", contents.fw_version_length,
+           reinterpret_cast<const char*>(payload));
   } else {
     printf("Received message type %s. [sequence=%u, %zu bytes]\n",
            to_string(header.message_type), header.sequence_number,
            message_size);
   }
 }
 
+/******************************************************************************/
+void PrintHex(const void* data, size_t data_len_bytes) {
+  const uint8_t* data_ptr = static_cast<const uint8_t*>(data);
+  for (size_t i = 0; i < data_len_bytes; ++i) {
+    printf("%02x", data_ptr[i]);
+    if (i < data_len_bytes - 1) {
+      printf(" ");
+    }
+  }
+}
+
 } // namespace examples
 } // namespace fusion_engine
 } // namespace point_one

examples/common/print_message.h

@@ -20,6 +20,8 @@ namespace examples {
 void PrintMessage(const fusion_engine::messages::MessageHeader& header,
                   const void* payload);
 
+void PrintHex(const void* data, size_t data_len_bytes);
+
 } // namespace examples
 } // namespace fusion_engine
 } // namespace point_one

examples/request_version/BUILD

@@ -0,0 +1,12 @@
+package(default_visibility = ["//visibility:public"])
+
+cc_binary(
+    name = "request_version",
+    srcs = [
+        "request_version.cc",
+    ],
+    deps = [
+        "//common:print_message",
+        "@fusion_engine_client",
+    ],
+)

examples/request_version/CMakeLists.txt

@@ -0,0 +1,3 @@
+add_executable(request_version request_version.cc)
+target_link_libraries(request_version PUBLIC fusion_engine_client)
+target_link_libraries(request_version PUBLIC print_message)

examples/request_version/request_version.cc

@@ -0,0 +1,138 @@
+/**************************************************************************/ /**
+* @brief Simulate sending a request for a version info message, and waiting for
+*        a response.
+* @file
+******************************************************************************/
+
+#include <cmath>
+#include <cstdio>
+#include <cstring>
+
+#include <point_one/fusion_engine/messages/core.h>
+#include <point_one/fusion_engine/messages/crc.h>
+#include <point_one/fusion_engine/parsers/fusion_engine_framer.h>
+
+#include "../common/print_message.h"
+
+using namespace point_one::fusion_engine::examples;
+using namespace point_one::fusion_engine::messages;
+using namespace point_one::fusion_engine::parsers;
+
+bool message_found = false;
+
+// Enforce a 4-byte aligned address.
+alignas(4) uint8_t storage[4096];
+
+// Fake Send/Receive functions.
+/******************************************************************************/
+void SendData(void* data, size_t data_len_bytes) {
+  (void)data;
+  (void)data_len_bytes;
+}
+
+/******************************************************************************/
+size_t ReceiveData(uint8_t* buffer, size_t read_size) {
+  static size_t offset = 0;
+  if (offset + read_size < sizeof(storage)) {
+    // We're using this data as if it were received from the device.
+    memcpy(buffer, storage + offset, read_size);
+    offset += read_size;
+    return read_size;
+  } else {
+    return 0;
+  }
+}
+
+/******************************************************************************/
+int main(int argc, const char* argv[]) {
+  if (argc != 1) {
+    printf("Usage: %s\n", argv[0]);
+    printf(R"EOF(
+Simulate sending a version request, and parsing the response.
+)EOF");
+    return 0;
+  }
+
+  //////////////////////////////////////////////////////////////////////////////
+  // Write a VersionInfoMessage request.
+  //////////////////////////////////////////////////////////////////////////////
+
+  uint8_t* buffer = storage;
+  auto header = reinterpret_cast<MessageHeader*>(buffer);
+  buffer += sizeof(MessageHeader);
+  *header = MessageHeader();
+
+  header->sequence_number = 0;
+  header->message_type = MessageType::MESSAGE_REQUEST;
+  header->payload_size_bytes = sizeof(MessageRequest);
+
+  auto req_message = reinterpret_cast<MessageRequest*>(buffer);
+  *req_message = MessageRequest();
+
+  req_message->message_type = VersionInfoMessage::MESSAGE_TYPE;
+
+  header->crc = CalculateCRC(storage);
+
+  printf("Sending VersionInfoMessage request:\n  ");
+  PrintHex(storage, sizeof(MessageHeader) + sizeof(MessageRequest));
+  // This data would be sent over serial to the device.
+  SendData(storage, sizeof(MessageHeader) + sizeof(MessageRequest));
+
+  printf("\n");
+
+  //////////////////////////////////////////////////////////////////////////////
+  // Generate an example response of the data a device would send back.
+  //////////////////////////////////////////////////////////////////////////////
+
+  static constexpr char VERSION_STR[] = {'t', 'e', 's', 't'};
+
+  // @ref ReceiveData will read data from `storage`.
+  buffer = storage;
+  header = reinterpret_cast<MessageHeader*>(buffer);
+  buffer += sizeof(MessageHeader);
+  *header = MessageHeader();
+
+  header->sequence_number = 0;
+  header->message_type = MessageType::VERSION_INFO;
+  header->payload_size_bytes = sizeof(VersionInfoMessage) + sizeof(VERSION_STR);
+
+  auto version_message = reinterpret_cast<VersionInfoMessage*>(buffer);
+  *version_message = VersionInfoMessage();
+  version_message->fw_version_length = sizeof(VERSION_STR);
+  buffer += sizeof(VersionInfoMessage);
+
+  char* version_str_ptr = reinterpret_cast<char*>(buffer);
+  // NOTE: Not NULL terminated.
+  memcpy(version_str_ptr, VERSION_STR, sizeof(VERSION_STR));
+
+  header->crc = CalculateCRC(storage);
+
+  //////////////////////////////////////////////////////////////////////////////
+  // Receive example response.
+  //////////////////////////////////////////////////////////////////////////////
+
+  printf("Waiting for response\n");
+  // In a real application, you'd need to do the bookkeeping to trigger a
+  // timeout if no response is received after a couple seconds.
+  bool has_timed_out = false;
+  uint8_t read_buffer[10];
+
+  FusionEngineFramer framer(1024);
+  framer.SetMessageCallback(
+      [](const MessageHeader& header, const void* payload) {
+        // Ignore messages besides the expected response type.
+        if (header.message_type == VersionInfoMessage::MESSAGE_TYPE) {
+          PrintMessage(header, payload);
+          message_found = true;
+        }
+      });
+
+  while (!has_timed_out && !message_found) {
+    size_t data_read = ReceiveData(read_buffer, sizeof(read_buffer));
+    framer.OnData(read_buffer, data_read);
+  }
+
+  printf("Response received.\n");
+
+  return 0;
+}