diff --git a/src/ringbuffer.cpp b/src/ringbuffer.cpp
new file mode 100644
--- /dev/null
+++ b/src/ringbuffer.cpp
@@ -0,0 +1,172 @@
+/*
+  Copyright © 2017 Hasan Yavuz Özderya
+
+  This file is part of serialplot.
+
+  serialplot 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.
+
+  serialplot 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 serialplot.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <QtGlobal>
+
+#include "ringbuffer.h"
+
+RingBuffer::RingBuffer(unsigned n)
+{
+    _size = n;
+    data = new double[_size]();
+    headIndex = 0;
+
+    limInvalid = false;
+    limCache = {0, 0};
+}
+
+RingBuffer::~RingBuffer()
+{
+    delete[] data;
+}
+
+unsigned RingBuffer::size() const
+{
+    return _size;
+}
+
+double RingBuffer::sample(unsigned i) const
+{
+    unsigned index = headIndex + i;
+    if (index >= _size) index -= _size;
+    return data[index];
+}
+
+Range RingBuffer::limits() const
+{
+    if (limInvalid) updateLimits();
+    return limCache;
+}
+
+void RingBuffer::resize(unsigned n)
+{
+    Q_ASSERT(n != _size);
+
+    int offset = (int) n - (int) _size;
+    if (offset == 0) return;
+
+    double* newData = new double[n];
+
+    // move data to new array
+    int fill_start = offset > 0 ? offset : 0;
+
+    for (int i = fill_start; i < int(n); i++)
+    {
+        newData[i] = sample(i - offset);
+    }
+
+    // fill the beginning of the new data
+    if (fill_start > 0)
+    {
+        for (int i = 0; i < fill_start; i++)
+        {
+            newData[i] = 0;
+        }
+    }
+
+    // data is ready, clean up and re-point
+    delete data;
+    data = newData;
+    headIndex = 0;
+    _size = n;
+
+    // invalidate bounding rectangle
+    limInvalid = true;
+}
+
+void RingBuffer::addSamples(double* samples, unsigned n)
+{
+    unsigned shift = n;
+    if (shift < _size)
+    {
+        unsigned x = _size - headIndex; // distance of `head` to end
+
+        if (shift <= x) // there is enough room at the end of array
+        {
+            for (unsigned i = 0; i < shift; i++)
+            {
+                data[i+headIndex] = samples[i];
+            }
+
+            if (shift == x) // we used all the room at the end
+            {
+                headIndex = 0;
+            }
+            else
+            {
+                headIndex += shift;
+            }
+        }
+        else // there isn't enough room
+        {
+            for (unsigned i = 0; i < x; i++) // fill the end part
+            {
+                data[i+headIndex] = samples[i];
+            }
+            for (unsigned i = 0; i < (shift-x); i++) // continue from the beginning
+            {
+                data[i] = samples[i+x];
+            }
+            headIndex = shift-x;
+        }
+    }
+    else // number of new samples equal or bigger than current size (doesn't fit)
+    {
+        int x = shift - _size;
+        for (unsigned i = 0; i < _size; i++)
+        {
+            data[i] = samples[i+x];
+        }
+        headIndex = 0;
+    }
+
+    // invalidate cache
+    limInvalid = true;
+}
+
+void RingBuffer::clear()
+{
+    for (unsigned i=0; i < _size; i++)
+    {
+        data[i] = 0.;
+    }
+
+    limCache = {0, 0};
+    limInvalid = false;
+}
+
+void RingBuffer::updateLimits() const
+{
+    limCache.start = data[0];
+    limCache.end = data[0];
+
+    for (unsigned i = 0; i < _size; i++)
+    {
+        if (data[i] > limCache.end)
+        {
+            limCache.end = data[i];
+        }
+        else if (data[i] < limCache.start)
+        {
+            limCache.start = data[i];
+        }
+    }
+
+    limInvalid = false;
+}