thehub/libs/utils/streaming/StreamingUtils.cpp

/*
 * This file is part of the Flowee project
 * Copyright (C) 2016-2025 Tom Zander <tom@flowee.org>
 *
 * This program 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, either version 3 of the License, or
 * (at your option) any later version.
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "StreamingUtils.h"
#include <cassert>
#include <cstring>
#include <limits>
#include <sstream>
#include <iomanip>

int Streaming::writeCompactSize(char *data, uint64_t value)
{
    int size = 1;
    if (value < 253) {
        // nothing to do
    }
    else if (value <= std::numeric_limits<unsigned short>::max()) {
        uint16_t copy = static_cast<uint16_t>(value);
        memcpy(data + 1, &copy, 2);
        size += 2;
        value = 253;
    }
    else if (value <= std::numeric_limits<unsigned int>::max()) {
        uint32_t copy = static_cast<uint32_t>(value);
        memcpy(data + 1, &copy, 4);
        size += 4;
        value = 254;
    }
    else {
        memcpy(data + 1, &value, 8);
        size += 8;
        value = 255;
    }
    *data = static_cast<uint8_t>(value);
    return size;
}

uint64_t Streaming::readCompactSize(const char **data, const char *end)
{
    if (end <= *data)
        return 0;
    uint8_t x = *(*data);
    if (x < 253) {
        (*data)++;
        return x;
    }
    if (x == 253) {
        if (end <= (*data) + 3) {
            *data = end;
            return 0;
        }
        (*data)++;
        uint64_t answer = *reinterpret_cast<const uint16_t*>(*data);
        *data += 2;
        return answer;
    }
    if (x == 254) {
        if (end <= (*data) + 5) {
            *data = end;
            return 0;
        }
        (*data)++;
        uint64_t answer = *reinterpret_cast<const uint32_t*>(*data);
        *data += 4;
        return answer;
    }
    assert(x == 255);
    if (end <= (*data) + 9) {
        *data = end;
        return 0;
    }
    (*data)++;
    uint64_t answer = *reinterpret_cast<const uint64_t*>(*data);
    *data += 8;
    return answer;
}

std::string Streaming::bytesToHex(const std::vector<char> &bytes)
{
    std::ostringstream oss;
    oss << std::hex << std::setfill('0');
    for (char c : bytes) {
        unsigned char byte = static_cast<unsigned char>(c);
        oss << std::setw(2) << static_cast<unsigned int>(byte);
    }
    return oss.str();
}