message_usb.hpp

// Copyright 2024 Google LLC
//
// 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
//
//     http://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 "libusb.hpp"
#include "message_intf.hpp"

#include <boost/endian/arithmetic.hpp>
#include <stdplus/handle/managed.hpp>

#include <array>
#include <string_view>

namespace google
{
namespace hoth
{

using boost::endian::little_uint32_t;
using boost::endian::little_uint8_t;

class MessageUSB : public MessageIntf
{
  public:
    explicit MessageUSB(std::string_view usb_id, LibusbIntf* libusb,
                        bool unit_test = false);

    void send(const uint8_t* buf, size_t size, size_t seek) override;
    void recv(uint8_t* buf, size_t size, size_t seek) override;

    static constexpr uint8_t kMailboxClass = 0xff;
    static constexpr std::array<const uint8_t, 2> kMailboxSubClasses{
        0x58, // New USB protocol
        0x71  // Old USB protocol
    };
    static constexpr uint8_t kMailboxProtocol = 0x01;

    // Hoths can only be full speed which limits buffers to 64B
    static constexpr uint16_t kMaxBulkTransferSize = 64;

    struct ReqHeader
    {
        static constexpr uint8_t kWrite = 0x02;
        static constexpr uint8_t kRead = 0x00;

        little_uint8_t type;
        little_uint32_t offset;
        little_uint8_t length;
    };

    struct RspHeader
    {
        little_uint8_t status;
        little_uint8_t rsvd;
    };

  private:
    libusb::Context ctx;
    libusb::Device dev;
    const libusb_interface_descriptor& interface;
    const libusb_endpoint_descriptor &in, &out;
    uint16_t maxInSize, maxOutSize;
    libusb::DeviceHandle handle;
    libusb::InterfaceClaim claim;
};

} // namespace hoth

} // namespace google