CDROM: Implement asynchronous disc reading

src/core/cdrom_async_reader.h

@@ -0,0 +1,56 @@
+#pragma once
+#include "common/cd_image.h"
+#include "types.h"
+#include <array>
+#include <atomic>
+#include <condition_variable>
+#include <thread>
+
+class CDROMAsyncReader
+{
+public:
+  using SectorBuffer = std::array<u8, CDImage::RAW_SECTOR_SIZE>;
+
+  CDROMAsyncReader();
+  ~CDROMAsyncReader();
+
+  const CDImage::LBA GetLastReadSector() const { return m_last_read_sector; }
+  const SectorBuffer& GetSectorBuffer() const { return m_sector_buffer; }
+  const CDImage::SubChannelQ& GetSectorSubQ() const { return m_subq; }
+  const bool HasMedia() const { return static_cast<bool>(m_media); }
+  const CDImage* GetMedia() const { return m_media.get(); }
+  const std::string GetMediaFileName() const { return m_media ? m_media->GetFileName() : std::string(); }
+
+  bool IsUsingThread() const { return m_read_thread.joinable(); }
+  void StartThread();
+  void StopThread();
+
+  void SetMedia(std::unique_ptr<CDImage> media);
+  void RemoveMedia();
+
+  void QueueReadSector(CDImage::LBA lba);
+  void QueueReadNextSector();
+
+  bool WaitForReadToComplete();
+
+private:
+  void DoSectorRead();
+  void WorkerThreadEntryPoint();
+
+  std::unique_ptr<CDImage> m_media;
+
+  std::mutex m_mutex;
+  std::thread m_read_thread;
+  std::condition_variable m_do_read_cv;
+  std::condition_variable m_notify_read_complete_cv;
+
+  CDImage::LBA m_next_position{};
+  std::atomic_bool m_next_position_set{false};
+  std::atomic_bool m_sector_read_pending{false};
+  std::atomic_bool m_shutdown_flag{true};
+
+  CDImage::LBA m_last_read_sector{};
+  CDImage::SubChannelQ m_subq{};
+  SectorBuffer m_sector_buffer{};
+  std::atomic_bool m_sector_read_result{false};
+};