src/random_access_file_type.h

   1 /*
   2  * This file is part of OpenTTD.
   3  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   4  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   5  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   6  */
   7
   8  /** @file random_access_file_type.h Class related to random access to files. */
   9
  10 #ifndef RANDOM_ACCESS_FILE_TYPE_H
  11 #define RANDOM_ACCESS_FILE_TYPE_H
  12
  13 #include "fileio_type.h"
  14
  15 /**
  16  * A file from which bytes, words and double words are read in (potentially) a random order.
  17  *
  18  * This is mostly intended to be used for things that can be read from GRFs when needed, so
  19  * the graphics but also the sounds. This also ties into the spritecache as it uses these
  20  * files to load the sprites from when needed.
  21  */
  22 class RandomAccessFile {
  23         /** The number of bytes to allocate for the buffer. */
  24         static constexpr int BUFFER_SIZE = 512;
  25
  26         std::string filename;            ///< Full name of the file; relative path to subdir plus the extension of the file.
  27         std::string simplified_filename; ///< Simplified lowecase name of the file; only the name, no path or extension.
  28
  29         std::optional<FileHandle> file_handle; ///< File handle of the open file.
  30         size_t pos;                      ///< Position in the file of the end of the read buffer.
  31         size_t start_pos; ///< Start position of file. May be non-zero if file is within a tar file.
  32         size_t end_pos; ///< End position of file.
  33
  34         uint8_t *buffer;                    ///< Current position within the local buffer.
  35         uint8_t *buffer_end;                ///< Last valid byte of buffer.
  36         uint8_t buffer_start[BUFFER_SIZE];  ///< Local buffer when read from file.
  37
  38 public:
  39         RandomAccessFile(const std::string &filename, Subdirectory subdir);
  40         RandomAccessFile(const RandomAccessFile&) = delete;
  41         void operator=(const RandomAccessFile&) = delete;
  42
  43         virtual ~RandomAccessFile() {}
  44
  45         const std::string &GetFilename() const;
  46         const std::string &GetSimplifiedFilename() const;
  47
  48         size_t GetPos() const;
  49         size_t GetStartPos() const { return this->start_pos; }
  50         size_t GetEndPos() const { return this->end_pos; }
  51         void SeekTo(size_t pos, int mode);
  52         bool AtEndOfFile() const;
  53
  54         uint8_t ReadByte();
  55         uint16_t ReadWord();
  56         uint32_t ReadDword();
  57
  58         void ReadBlock(void *ptr, size_t size);
  59         void SkipBytes(size_t n);
  60 };
  61
  62 #endif /* RANDOM_ACCESS_FILE_TYPE_H */