encoder.h

// 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.
#pragma once
 
#include <cstddef>
#include <cstdint>
 
#include "pw_bytes/span.h"
#include "pw_checksum/crc32.h"
#include "pw_hdlc/internal/protocol.h"
#include "pw_status/status.h"
#include "pw_stream/stream.h"
 
namespace pw::hdlc {
 
Status WriteUIFrame(uint64_t address,
                    ConstByteSpan payload,
                    stream::Writer& writer);
 
class Encoder {
 public:
  constexpr Encoder(stream::Writer& output) : writer_(output) {}
 
  Status StartUnnumberedFrame(uint64_t address) {
    return StartFrame(address, UFrameControl::UnnumberedInformation().data());
  }
 
  Status WriteData(ConstByteSpan data);
 
  Status FinishFrame();
 
 private:
  // Indicates this an information packet with sequence numbers set to 0.
  static constexpr std::byte kUnusedControl = std::byte{0};
 
  Status StartFrame(uint64_t address, std::byte control);
 
  stream::Writer& writer_;
  checksum::Crc32 fcs_;
};
 
}  // namespace pw::hdlc