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diff --git a/src/chunks.h b/src/chunks.h
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+#ifndef CHUNKS_H
+#define CHUNKS_H
+
+/** \cond docNever */
+
+/*! The Chunks class is the storage backend for QHexEdit.
+ *
+ * When QHexEdit loads data, Chunks access them using a QIODevice interface. When the app uses
+ * a QByteArray interface, QBuffer is used to provide again a QIODevice like interface. No data
+ * will be changed, therefore Chunks opens the QIODevice in QIODevice::ReadOnly mode. After every
+ * access Chunks closes the QIODevice, that's why external applications can overwrite files while
+ * QHexEdit shows them.
+ *
+ * When the the user starts to edit the data, Chunks creates a local copy of a chunk of data (4
+ * kilobytes) and notes all changes there. Parallel to that chunk, there is a second chunk,
+ * which keep track of which bytes are changed and which not.
+ *
+ */
+
+#include <QtCore>
+
+struct Chunk
+{
+    QByteArray data;
+    QByteArray dataChanged;
+    qint64 absPos;
+};
+
+class Chunks: public QObject
+{
+Q_OBJECT
+public:
+    // Constructors and file settings
+    Chunks(QObject *parent);
+    Chunks(QIODevice &ioDevice, QObject *parent);
+    bool setIODevice(QIODevice &ioDevice);
+
+    // Getting data out of Chunks
+    QByteArray data(qint64 pos=0, qint64 count=-1, QByteArray *highlighted=0);
+    bool write(QIODevice &iODevice, qint64 pos=0, qint64 count=-1);
+
+    // Set and get highlighting infos
+    void setDataChanged(qint64 pos, bool dataChanged);
+    bool dataChanged(qint64 pos);
+
+    // Search API
+    qint64 indexOf(const QByteArray &ba, qint64 from);
+    qint64 lastIndexOf(const QByteArray &ba, qint64 from);
+
+    // Char manipulations
+    bool insert(qint64 pos, char b);
+    bool overwrite(qint64 pos, char b);
+    bool removeAt(qint64 pos);
+
+    // Utility functions
+    char operator[](qint64 pos);
+    qint64 pos();
+    qint64 size();
+
+
+private:
+    int getChunkIndex(qint64 absPos);
+
+    QIODevice * _ioDevice;
+    qint64 _pos;
+    qint64 _size;
+    QList<Chunk> _chunks;
+
+#ifdef MODUL_TEST
+public:
+    int chunkSize();
+#endif
+};
+
+/** \endcond docNever */
+
+#endif // CHUNKS_H