XorOutputStream.h

Go to the documentation of this file.

/****
 * Sming Framework Project - Open Source framework for high efficiency native ESP8266 development.
 * Created 2015 by Skurydin Alexey
 * http://github.com/SmingHub/Sming
 * All files of the Sming Core are provided under the LGPL v3 license.
 *
 * XorOutputStream.h
 *
 * @author Slavey Karadzhov <slaff@attachix.com>
 *
 ****/

#pragma once

#include <Data/Stream/DataSourceStream.h>

class XorOutputStream : public IDataSourceStream
{
public:
    XorOutputStream(IDataSourceStream* stream, uint8_t* mask, size_t maskLength)
        : stream(stream), mask(mask), maskLength(maskLength)
    {
    }

    StreamType getStreamType() const override
    {
        return eSST_Transform;
    }

    int available() override
    {
        return stream->available();
    }

    uint16_t readMemoryBlock(char* data, int bufSize) override
    {
        uint16_t max = stream->readMemoryBlock(data, bufSize);
        size_t pos = maskPos;
        for(unsigned i = 0; i < max; i++) {
            pos = pos % maskLength;
            data[i] = (data[i] ^ mask[pos]);
            pos++;
        }

        return max;
    }

    bool seek(int len) override
    {
        if(!stream->seek(len)) {
            return false;
        }

        maskPos = (maskPos + len) % maskLength;
        return true;
    }

    bool isFinished() override
    {
        return stream->isFinished();
    }

private:
    std::unique_ptr<IDataSourceStream> stream;
    uint8_t* mask;
    size_t maskLength;
    size_t maskPos = 0;
};