add leveldb

1 files changed, 87 insertions, 0 deletions

diff --git a/src/database/include/table.hpp b/src/database/include/table.hpp
new file mode 100644
index 00000000..438c23b6
--- /dev/null
+++ b/src/database/include/table.hpp
@@ -0,0 +1,87 @@
+#pragma once
+
+#include <cstddef>
+#include <cstdint>
+#include <memory>
+#include <optional>
+#include <string>
+#include <utility>
+
+#include "esp32/himem.h"
+#include "ff.h"
+#include "span.hpp"
+#include "sys/_stdint.h"
+
+namespace database {
+
+// Types used for indexing into files on disk. These should, at minimum, match
+// the size of the types that the underlying filesystem uses to address within
+// files. FAT32 uses 32 bit address. If we drop this and just support exFAT, we
+// can change these to 64 bit types.
+typedef uint32_t Index_t;
+typedef Index_t IndexOffset_t;
+
+// The amount of memory that will be used to page database columns in from disk.
+// Currently we only use a single 'page' in PSRAM per column, but with some
+// refactoring we could easily page more.
+// Keep this value 32KiB-aligned for himem compatibility.
+extern const std::size_t kRamBlockSize;
+
+struct DatabaseHeader {
+  uint32_t magic_number;
+  uint16_t db_version;
+  Index_t num_indices;
+};
+
+struct DatabaseEntry {
+  uint8_t type;
+  std::string path;
+
+  std::string title;
+  std::string album;
+  std::string artist;
+  std::string album_artist;
+};
+
+struct IndexEntry {
+  uint8_t type;
+  IndexOffset_t path;
+
+  IndexOffset_t title;
+  IndexOffset_t album;
+  IndexOffset_t artist;
+  IndexOffset_t album_artist;
+};
+
+struct RowData {
+  std::unique_ptr<std::byte[]> arr;
+  std::size_t length;
+};
+
+// Representation of a single column of data. Each column is simply a tightly
+// packed list of [size, [bytes, ...]] pairs. Callers are responsible for
+// parsing and encoding the actual bytes themselves.
+class Column {
+ public:
+  static auto Open(std::string) -> std::optional<Column>;
+
+  Column(FIL file, std::size_t file_size);
+  ~Column();
+
+  auto ReadDataAtOffset(esp_himem_rangehandle_t, IndexOffset_t) -> RowData;
+  auto AppendRow(cpp::span<std::byte> row) -> bool;
+  auto FlushChanges() -> void;
+
+ private:
+  FIL file_;
+  IndexOffset_t length_;
+
+  esp_himem_handle_t block_;
+  std::pair<IndexOffset_t, IndexOffset_t> loaded_range_;
+
+  auto IsOffsetLoaded(IndexOffset_t offset) -> bool;
+  auto LoadOffsetFromDisk(cpp::span<std::byte> dest, IndexOffset_t offset)
+      -> bool;
+};
+
+}  // namespace database