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94 lines
3.2 KiB
C++
94 lines
3.2 KiB
C++
/*
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* This file is part of OpenTTD.
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* 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.
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* 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.
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* 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/>.
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*/
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/** @file random_access_file_type.h Class related to random access to files. */
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#ifndef RANDOM_ACCESS_FILE_TYPE_H
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#define RANDOM_ACCESS_FILE_TYPE_H
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#include "fileio_type.h"
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#include "core/endian_func.hpp"
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#include <string>
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/**
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* A file from which bytes, words and double words are read in (potentially) a random order.
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*
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* This is mostly intended to be used for things that can be read from GRFs when needed, so
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* the graphics but also the sounds. This also ties into the spritecache as it uses these
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* files to load the sprites from when needed.
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*/
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class RandomAccessFile {
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/** The number of bytes to allocate for the buffer. */
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static constexpr int BUFFER_SIZE = 4096;
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std::string filename; ///< Full name of the file; relative path to subdir plus the extension of the file.
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std::string simplified_filename; ///< Simplified lowecase name of the file; only the name, no path or extension.
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FILE *file_handle; ///< File handle of the open file.
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size_t pos; ///< Position in the file of the end of the read buffer.
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byte *buffer; ///< Current position within the local buffer.
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byte *buffer_end; ///< Last valid byte of buffer.
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byte buffer_start[BUFFER_SIZE]; ///< Local buffer when read from file.
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byte ReadByteIntl();
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uint16_t ReadWordIntl();
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uint32_t ReadDwordIntl();
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public:
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RandomAccessFile(const std::string &filename, Subdirectory subdir);
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RandomAccessFile(const RandomAccessFile&) = delete;
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void operator=(const RandomAccessFile&) = delete;
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virtual ~RandomAccessFile();
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const std::string &GetFilename() const;
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const std::string &GetSimplifiedFilename() const;
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size_t GetPos() const;
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void SeekTo(size_t pos, int mode);
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inline byte ReadByte()
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{
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if (likely(this->buffer != this->buffer_end)) return *this->buffer++;
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return this->ReadByteIntl();
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}
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inline uint16_t ReadWord()
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{
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if (likely(this->buffer + 1 < this->buffer_end)) {
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#if OTTD_ALIGNMENT == 0
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uint16_t x = FROM_LE16(*((const unaligned_uint16 *) this->buffer));
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#else
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uint16_t x = ((uint16_t)this->buffer[1] << 8) | this->buffer[0];
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#endif
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this->buffer += 2;
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return x;
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}
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return this->ReadWordIntl();
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}
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inline uint32_t ReadDword()
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{
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if (likely(this->buffer + 3 < this->buffer_end)) {
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#if OTTD_ALIGNMENT == 0
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uint32_t x = FROM_LE32(*((const unaligned_uint32 *) this->buffer));
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#else
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uint32_t x = ((uint32_t)this->buffer[3] << 24) | ((uint32_t)this->buffer[2] << 16) | ((uint32_t)this->buffer[1] << 8) | this->buffer[0];
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#endif
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this->buffer += 4;
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return x;
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}
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return this->ReadDwordIntl();
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}
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void ReadBlock(void *ptr, size_t size);
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void SkipBytes(size_t n);
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};
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#endif /* RANDOM_ACCESS_FILE_TYPE_H */
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