third_party/pigweed/repo/pw_hdlc_lite/public/pw_hdlc_lite/rpc_channel.h

   1 // Copyright 2020 The Pigweed Authors
   2 //
   3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not
   4 // use this file except in compliance with the License. You may obtain a copy of
   5 // the License at
   6 //
   7 //     https://www.apache.org/licenses/LICENSE-2.0
   8 //
   9 // Unless required by applicable law or agreed to in writing, software
  10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  12 // License for the specific language governing permissions and limitations under
  13 // the License.
  14 #pragma once
  15
  16 #include <array>
  17 #include <span>
  18
  19 #include "pw_hdlc_lite/encoder.h"
  20 #include "pw_rpc/channel.h"
  21 #include "pw_stream/stream.h"
  22
  23 namespace pw::hdlc_lite {
  24
  25 // Custom HDLC ChannelOutput class to write and read data through serial using
  26 // the HDLC-Lite protocol.
  27 class RpcChannelOutput : public rpc::ChannelOutput {
  28  public:
  29   // The RpcChannelOutput class does not own the buffer it uses to store the
  30   // protobuf bytes. This buffer is specified at the time of creation along with
  31   // a writer object to which will be used to write and send the bytes.
  32   constexpr RpcChannelOutput(stream::Writer& writer,
  33                              std::span<std::byte> buffer,
  34                              uint8_t address,
  35                              const char* channel_name)
  36       : ChannelOutput(channel_name),
  37         writer_(writer),
  38         buffer_(buffer),
  39         address_(address) {}
  40
  41   std::span<std::byte> AcquireBuffer() override { return buffer_; }
  42
  43   Status SendAndReleaseBuffer(size_t size) override {
  44     return hdlc_lite::WriteInformationFrame(
  45         address_, buffer_.first(size), writer_);
  46   }
  47
  48  private:
  49   stream::Writer& writer_;
  50   const std::span<std::byte> buffer_;
  51   const uint8_t address_;
  52 };
  53
  54 // RpcChannelOutput with its own buffer.
  55 template <size_t buffer_size>
  56 class RpcChannelOutputBuffer : public rpc::ChannelOutput {
  57  public:
  58   constexpr RpcChannelOutputBuffer(stream::Writer& writer,
  59                                    uint8_t address,
  60                                    const char* channel_name)
  61       : ChannelOutput(channel_name), writer_(writer), address_(address) {}
  62
  63   std::span<std::byte> AcquireBuffer() override { return buffer_; }
  64
  65   Status SendAndReleaseBuffer(size_t size) override {
  66     return hdlc_lite::WriteInformationFrame(
  67         address_, std::span(buffer_.data(), size), writer_);
  68   }
  69
  70  private:
  71   stream::Writer& writer_;
  72   std::array<std::byte, buffer_size> buffer_;
  73   const uint8_t address_;
  74 };
  75
  76 }  // namespace pw::hdlc_lite