FOSS-VG/src/lib/nbt.cpp

// Copyright 2022, FOSS-VG Developers and Contributers
//
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, version 3.
//
// This program 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.
// See the GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// version 3 along with this program.
// If not, see https://www.gnu.org/licenses/agpl-3.0.en.html

#include <bit>
#include <cstdint>
#include <vector>

#include "nbt.h++"
#include "error.h++"

// This is just an example for how to find out if the system is big endian
// or little endian. Do not use this.
int endianness_example() {
    if constexpr (std::endian::native == std::endian::big)
    {
        // Big-endian system
        return 0;
    }
    else if constexpr (std::endian::native == std::endian::little)
    {
        // Little-endian system
        return 1;
    }
    else
    {
        // Something else
        return 2;
        // How did we even end up here?
    }
}

namespace NBT {
    namespace helper {
        ErrorOr<int8_t> readInt8(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
            if (dataSize<=currentPosition) return ErrorOr<int8_t>(true, ErrorCodes::RANGE_ERROR);
            return ErrorOr<int8_t>((int8_t) data[currentPosition]);
        }

        ErrorOr<int16_t> readInt16(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
            //TODO: implement
            return ErrorOr<int16_t>((int16_t) 0);
        }

        ErrorOr<int32_t> readInt32(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
            //TODO: implement
            return ErrorOr<int32_t>((int32_t) 0);
        }

        ErrorOr<int64_t> readInt64(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
            //TODO: implement
            return ErrorOr<int64_t>((int64_t) 0);
        }

        //FIXME: we just assume that float is a single-precision IEEE754
        // floating point number
        ErrorOr<float> readFloat32(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
            //TODO: implement assuming standard single-precision IEEE754 float
            // Alternatively, maybe calculate a floating point number by using
            // the stored value as math instructions?
            return ErrorOr<float>(0.0f);
        }

        //FIXME: we just assume that double is a double-precision IEEE754
        // floating point number
        ErrorOr<double> readFloat64(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
            //TODO: implement assuming standard double-precision IEEE754 float
            // Alternatively, maybe calculate a floating point number by using
            // the stored value as math instructions?
            return ErrorOr<double>(0.0);
        }

        ErrorOr<std::vector<int8_t>> readInt8Array(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
            //TODO: implement
            return ErrorOr<std::vector<int8_t>>({0});
        }

        // Maybe use a struct that holds decoded (de-Java-fied) string
        // data, decoded size, and original size? Original size is needed
        // so the parser knows where to continue.
        //ErrorOr<> readString(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
            //TODO: implement
            // return ErrorOr<>("");
        //}

        ErrorOr<std::vector<int32_t>> readInt32Array(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
            //TODO: implement
            return ErrorOr<std::vector<int32_t>>({0});
        }

        ErrorOr<std::vector<int64_t>> readInt64Array(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
            //TODO: implement
            return ErrorOr<std::vector<int64_t>>({0});
        }
    }

    bool validateRawNBTData(uint8_t data[], uint64_t dataSize){
        //state machine?
        //TODO: implement
        return false;
    }
}