third_party/pigweed/repo/pw_hdlc/public/pw_hdlc/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_assert/light.h"
  20 #include "pw_hdlc/encoder.h"
  21 #include "pw_rpc/channel.h"
  22 #include "pw_stream/stream.h"
  23
  24 namespace pw::hdlc {
  25
  26 // Custom HDLC ChannelOutput class to write and read data through serial using
  27 // the HDLC protocol.
  28 //
  29 // WARNING: This ChannelOutput is not thread-safe. If thread-safety is required,
  30 // wrap this in a pw::rpc::SynchronizedChannelOutput.
  31 class RpcChannelOutput : public rpc::ChannelOutput {
  32  public:
  33   // The RpcChannelOutput class does not own the buffer it uses to store the
  34   // protobuf bytes. This buffer is specified at the time of creation along with
  35   // a writer object to which will be used to write and send the bytes.
  36   constexpr RpcChannelOutput(stream::Writer& writer,
  37                              std::span<std::byte> buffer,
  38                              uint8_t address,
  39                              const char* channel_name)
  40       : ChannelOutput(channel_name),
  41         writer_(writer),
  42         buffer_(buffer),
  43         address_(address) {}
  44
  45   std::span<std::byte> AcquireBuffer() override { return buffer_; }
  46
  47   Status SendAndReleaseBuffer(std::span<const std::byte> buffer) override {
  48     PW_DASSERT(buffer.data() == buffer_.data());
  49     if (buffer.empty()) {
  50       return OkStatus();
  51     }
  52     return hdlc::WriteUIFrame(address_, buffer, writer_);
  53   }
  54
  55  private:
  56   stream::Writer& writer_;
  57   const std::span<std::byte> buffer_;
  58   const uint8_t address_;
  59 };
  60
  61 // RpcChannelOutput with its own buffer.
  62 //
  63 // WARNING: This ChannelOutput is not thread-safe. If thread-safety is required,
  64 // wrap this in a pw::rpc::SynchronizedChannelOutput.
  65 template <size_t buffer_size>
  66 class RpcChannelOutputBuffer : public rpc::ChannelOutput {
  67  public:
  68   constexpr RpcChannelOutputBuffer(stream::Writer& writer,
  69                                    uint8_t address,
  70                                    const char* channel_name)
  71       : ChannelOutput(channel_name), writer_(writer), address_(address) {}
  72
  73   std::span<std::byte> AcquireBuffer() override { return buffer_; }
  74
  75   Status SendAndReleaseBuffer(std::span<const std::byte> buffer) override {
  76     PW_DASSERT(buffer.data() == buffer_.data());
  77     if (buffer.empty()) {
  78       return OkStatus();
  79     }
  80     return hdlc::WriteUIFrame(address_, buffer, writer_);
  81   }
  82
  83  private:
  84   stream::Writer& writer_;
  85   std::array<std::byte, buffer_size> buffer_;
  86   const uint8_t address_;
  87 };
  88
  89 }  // namespace pw::hdlc