1 files changed, 77 insertions, 0 deletions
diff --git a/pw_hdlc/hdlc_sys_io_system_server.cc b/pw_hdlc/hdlc_sys_io_system_server.cc
new file mode 100644
index 000000000..684f1786e
--- /dev/null
+++ b/pw_hdlc/hdlc_sys_io_system_server.cc
@@ -0,0 +1,77 @@
+// Copyright 2022 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 <cstddef>
+
+#include "pw_hdlc/encoded_size.h"
+#include "pw_hdlc/rpc_channel.h"
+#include "pw_hdlc/rpc_packets.h"
+#include "pw_log/log.h"
+#include "pw_rpc_system_server/rpc_server.h"
+#include "pw_stream/sys_io_stream.h"
+
+namespace pw::rpc::system_server {
+namespace {
+
+// Hard-coded to 1055 bytes, which is enough to fit 512-byte payloads when using
+// HDLC framing.
+constexpr size_t kMaxTransmissionUnit = 1055;
+
+static_assert(kMaxTransmissionUnit ==
+              hdlc::MaxEncodedFrameSize(rpc::cfg::kEncodingBufferSizeBytes));
+
+// Used to write HDLC data to pw::sys_io.
+stream::SysIoWriter writer;
+
+// Set up the output channel for the pw_rpc server to use.
+hdlc::FixedMtuChannelOutput<kMaxTransmissionUnit> hdlc_channel_output(
+    writer, pw::hdlc::kDefaultRpcAddress, "HDLC channel");
+Channel channels[] = {pw::rpc::Channel::Create<1>(&hdlc_channel_output)};
+rpc::Server server(channels);
+
+}  // namespace
+
+void Init() {
+  // 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::WriteUIFrame(1, as_bytes(span<const char>(log)), writer);
+  });
+}
+
+rpc::Server& Server() { return server; }
+
+Status Start() {
+  constexpr size_t kDecoderBufferSize =
+      hdlc::Decoder::RequiredBufferSizeForFrameSize(kMaxTransmissionUnit);
+  // Declare a buffer for decoding incoming HDLC frames.
+  std::array<std::byte, kDecoderBufferSize> input_buffer;
+  hdlc::Decoder decoder(input_buffer);
+
+  while (true) {
+    std::byte byte;
+    Status ret_val = pw::sys_io::ReadByte(&byte);
+    if (!ret_val.ok()) {
+      return ret_val;
+    }
+    if (auto result = decoder.Process(byte); result.ok()) {
+      hdlc::Frame& frame = result.value();
+      if (frame.address() == hdlc::kDefaultRpcAddress) {
+        server.ProcessPacket(frame.data());
+      }
+    }
+  }
+}
+
+}  // namespace pw::rpc::system_server