1 files changed, 126 insertions, 0 deletions
diff --git a/src/engine/filters/enginefilterdelay.h b/src/engine/filters/enginefilterdelay.h
new file mode 100644
index 0000000000..8071338c56
--- /dev/null
+++ b/src/engine/filters/enginefilterdelay.h
@@ -0,0 +1,126 @@
+#ifndef ENGINEFILTERDELAY_H
+#define ENGINEFILTERDELAY_H
+
+#include "engine/engineobject.h"
+#include "util/assert.h"
+#include "util/sample.h"
+
+template<unsigned int SIZE>
+class EngineFilterDelay : public EngineObjectConstIn {
+  public:
+    EngineFilterDelay()
+            : m_delaySamples(0),
+              m_oldDelaySamples(0),
+              m_delayPos(0),
+              m_doStart(false) {
+        // Set the current buffers to 0
+        memset(m_buf, 0, sizeof(m_buf));
+    }
+
+    virtual ~EngineFilterDelay() {};
+
+    void pauseFilter() {
+        // Set the current buffers to 0
+        if (!m_doStart) {
+            memset(m_buf, 0, sizeof(m_buf));
+            m_oldDelaySamples = 0;
+            m_doStart = true;
+        }
+    }
+
+    void setDelay(unsigned int delaySamples) {
+        m_delaySamples = delaySamples;
+    }
+
+    virtual void process(const CSAMPLE* pIn, CSAMPLE* pOutput,
+                         const int iBufferSize) {
+        if (m_oldDelaySamples == m_delaySamples) {
+            int delaySourcePos = (m_delayPos + SIZE - m_delaySamples) % SIZE;
+
+            VERIFY_OR_DEBUG_ASSERT(delaySourcePos >= 0) {
+                SampleUtil::copy(pOutput, pIn, iBufferSize);
+                return;
+            }
+            VERIFY_OR_DEBUG_ASSERT(delaySourcePos <= static_cast<int>(SIZE)) {
+                SampleUtil::copy(pOutput, pIn, iBufferSize);
+                return;
+            }
+
+            for (int i = 0; i < iBufferSize; ++i) {
+                // put sample into delay buffer:
+                m_buf[m_delayPos] = pIn[i];
+                m_delayPos = (m_delayPos + 1) % SIZE;
+
+                // Take delayed sample from delay buffer and copy it to dest buffer:
+                pOutput[i] = m_buf[delaySourcePos];
+                delaySourcePos = (delaySourcePos + 1) % SIZE;
+            }
+        } else {
+            int delaySourcePos = (m_delayPos + SIZE - m_delaySamples + iBufferSize / 2) % SIZE;
+            int oldDelaySourcePos = (m_delayPos + SIZE - m_oldDelaySamples) % SIZE;
+
+            VERIFY_OR_DEBUG_ASSERT(delaySourcePos >= 0) {
+                SampleUtil::copy(pOutput, pIn, iBufferSize);
+                return;
+            }
+            VERIFY_OR_DEBUG_ASSERT(delaySourcePos <= static_cast<int>(SIZE)) {
+                SampleUtil::copy(pOutput, pIn, iBufferSize);
+                return;
+            }
+            VERIFY_OR_DEBUG_ASSERT(oldDelaySourcePos >= 0) {
+                SampleUtil::copy(pOutput, pIn, iBufferSize);
+                return;
+            }
+            VERIFY_OR_DEBUG_ASSERT(oldDelaySourcePos <= static_cast<int>(SIZE)) {
+                SampleUtil::copy(pOutput, pIn, iBufferSize);
+                return;
+            }
+
+            double cross_mix = 0.0;
+            double cross_inc = 2 / static_cast<double>(iBufferSize);
+
+            for (int i = 0; i < iBufferSize; ++i) {
+                // put sample into delay buffer:
+                m_buf[m_delayPos] = pIn[i];
+                m_delayPos = (m_delayPos + 1) % SIZE;
+
+                // Take delayed sample from delay buffer and copy it to dest buffer:
+                if (i < iBufferSize / 2) {
+                    // only ramp the second half of the buffer, because we do
+                    // the same in the IIR filter to wait for settling
+                    pOutput[i] = m_buf[oldDelaySourcePos];
+                } else {
+                    pOutput[i] = m_buf[oldDelaySourcePos] * (1.0 - cross_mix);
+                    pOutput[i] += m_buf[delaySourcePos] * cross_mix;
+                    delaySourcePos = (delaySourcePos + 1) % SIZE;
+                    cross_mix += cross_inc;
+                }
+                oldDelaySourcePos = (oldDelaySourcePos + 1) % SIZE;
+            }
+            m_oldDelaySamples = m_delaySamples;
+        }
+        m_doStart = false;
+    }
+
+
+    // this is can be used instead off a final process() call before pause
+    // It fades to dry or 0 according to the m_startFromDry parameter
+    // it is an alternative for using pauseFillter() calls
+    void processAndPauseFilter(const CSAMPLE* pIn, CSAMPLE* pOutput,
+                       const int iBufferSize) {
+        double oldDelay = m_delaySamples;
+        m_delaySamples = 0;
+        process(pIn, pOutput, iBufferSize);
+        m_delaySamples = oldDelay;
+        pauseFilter();
+    }
+
+  protected:
+    int m_delaySamples;
+    int m_oldDelaySamples;
+    int m_delayPos;
+    double m_buf[SIZE];
+    bool m_doStart;
+};
+
+#endif // ENGINEFILTERDELAY_H