serialization.h

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// Luanti
// SPDX-License-Identifier: LGPL-2.1-or-later
// Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
 
#pragma once
 
#include "irrlichttypes.h"
#include <iostream>
#include <string_view>
 
/*
        Map format serialization version
        --------------------------------
 
        For map data (blocks, nodes, sectors).
 
        NOTE: The goal is to increment this so that saved maps will be
              loadable by any version. Other compatibility is not
                  maintained.
 
        0: original networked test with 1-byte nodes
        1: update with 2-byte nodes
        2: lighting is transmitted in param
        3: optional fetching of far blocks
        4: block compression
        5: sector objects NOTE: block compression was left accidentally out
        6: failed attempt at switching block compression on again
        7: block compression switched on again
        8: server-initiated block transfers and all kinds of stuff
        9: block objects
        10: water pressure
        11: zlib'd blocks, block flags
        12: UnlimitedHeightmap now uses interpolated areas
        13: Mapgen v2
        14: NodeMetadata
        15: StaticObjects
        16: larger maximum size of node metadata, and compression
        17: MapBlocks contain timestamp
        18: new generator (not really necessary, but it's there)
        19: new content type handling
        20: many existing content types translated to extended ones
        21: dynamic content type allocation
        22: minerals removed, facedir & wallmounted changed
        23: new node metadata format
        24: 16-bit node ids and node timers (never released as stable)
        25: Improved node timer format
        26: Never written; read the same as 25
        27: Added light spreading flags to blocks
        28: Added "private" flag to NodeMetadata
        29: Switched compression to zstd, a bit of reorganization
*/
 
// This represents an uninitialized or invalid format
constexpr u8 SER_FMT_VER_INVALID = 255;
// Highest supported serialization version
constexpr u8 SER_FMT_VER_HIGHEST_READ = 29;
// Saved on disk version
constexpr u8 SER_FMT_VER_HIGHEST_WRITE = 29;
// Lowest supported serialization version
constexpr u8 SER_FMT_VER_LOWEST_READ = 0;
// Lowest serialization version for writing
// Can't do < 24 anymore; we have 16-bit dynamically allocated node IDs
// in memory; conversion just won't work in this direction.
constexpr u8 SER_FMT_VER_LOWEST_WRITE = 24;
 
inline bool ser_ver_supported_read(s32 v)
{
        return v >= SER_FMT_VER_LOWEST_READ && v <= SER_FMT_VER_HIGHEST_READ;
}
 
inline bool ser_ver_supported_write(s32 v)
{
        return v >= SER_FMT_VER_LOWEST_WRITE && v <= SER_FMT_VER_HIGHEST_WRITE;
}
 
/*
        Compression functions
*/
 
void compressZlib(const u8 *data, size_t data_size, std::ostream &os, int level = -1);
inline void compressZlib(std::string_view data, std::ostream &os, int level = -1)
{
        compressZlib(reinterpret_cast<const u8*>(data.data()), data.size(), os, level);
}
void decompressZlib(std::istream &is, std::ostream &os, size_t limit = 0);
 
void compressZstd(const u8 *data, size_t data_size, std::ostream &os, int level = 0);
inline void compressZstd(std::string_view data, std::ostream &os, int level = 0)
{
        compressZstd(reinterpret_cast<const u8*>(data.data()), data.size(), os, level);
}
void decompressZstd(std::istream &is, std::ostream &os);
 
// These choose between zstd, zlib and a self-made one according to version
void compress(const u8 *data, u32 size, std::ostream &os, u8 version, int level = -1);
inline void compress(std::string_view data, std::ostream &os, u8 version, int level = -1)
{
        compress(reinterpret_cast<const u8*>(data.data()), data.size(), os, version, level);
}
void decompress(std::istream &is, std::ostream &os, u8 version);