pw_hdlc_lite/rpc_example/hdlc_rpc_server.cc

// Copyright 2020 The Pigweed Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.

#include <array>
#include <span>
#include <string_view>

#include "pw_hdlc_lite/encoder.h"
#include "pw_hdlc_lite/rpc_channel.h"
#include "pw_hdlc_lite/rpc_packets.h"
#include "pw_hdlc_lite/sys_io_stream.h"
#include "pw_log/log.h"
#include "pw_rpc/echo_service_nanopb.h"
#include "pw_rpc/server.h"

namespace hdlc_example {
namespace {

using std::byte;

constexpr size_t kMaxTransmissionUnit = 256;

// Used to write HDLC data to pw::sys_io.
pw::stream::SysIoWriter writer;

// Set up the output channel for the pw_rpc server to use to use.
std::array<byte, kMaxTransmissionUnit> output_buffer;
pw::rpc::HdlcChannelOutput hdlc_channel_output(
    writer,
    output_buffer,
    pw::hdlc_lite::kDefaultRpcAddress,
    "HdlcChannelOutput");

pw::rpc::Channel channels[] = {
    pw::rpc::Channel::Create<1>(&hdlc_channel_output)};

// Declare the pw_rpc server with the HDLC channel.
pw::rpc::Server server(channels);

pw::rpc::EchoService echo_service;

void RegisterServices() { server.RegisterService(echo_service); }

}  // namespace

void Start() {
  // Send log messages to HDLC address 1. This prevents logs from interfering
  // with pw_rpc communications.
  pw::log_basic::SetOutput([](std::string_view log) {
    pw::hdlc_lite::WriteInformationFrame(
        1, std::as_bytes(std::span(log)), writer);
  });

  // Set up the server and start processing data.
  RegisterServices();

  // Declare a buffer for decoding incoming HDLC frames.
  std::array<std::byte, kMaxTransmissionUnit> input_buffer;

  PW_LOG_INFO("Starting pw_rpc server");
  pw::hdlc_lite::ReadAndProcessPackets(
      server, hdlc_channel_output, input_buffer);
}

}  // namespace hdlc_example