From 7cfcc61bd38a8632c8a67a68e6153126102b9943 Mon Sep 17 00:00:00 2001
From: Klaus Basan <klaus.basan@klausbasan.de>
Date: Fri, 18 Oct 2019 12:11:18 +0200
Subject: [PATCH] Doxygen/style, test for div/0

---
 src/blacksound/dsp/biquadfilter.cpp | 28 +++++++++++++++++-----------
 src/blacksound/dsp/biquadfilter.h   | 28 +++++++++++++++++-----------
 2 files changed, 34 insertions(+), 22 deletions(-)

diff --git a/src/blacksound/dsp/biquadfilter.cpp b/src/blacksound/dsp/biquadfilter.cpp
index e19a2e74a..9e8ca2c9d 100644
--- a/src/blacksound/dsp/biquadfilter.cpp
+++ b/src/blacksound/dsp/biquadfilter.cpp
@@ -7,10 +7,14 @@
  */
 
 #include "biquadfilter.h"
+#include "blackmisc/verify.h"
+#include "blackconfig/buildconfig.h"
 
 #include <QtMath>
 #include <algorithm>
 
+using namespace BlackMisc;
+using namespace BlackConfig;
 
 namespace BlackSound
 {
@@ -19,27 +23,29 @@ namespace BlackSound
         float BiQuadFilter::transform(float inSample)
         {
             // compute result
-            double result = a0 * inSample + a1 * x1 + a2 * x2 - a3 * y1 - a4 * y2;
+            double result = m_a0 * inSample + m_a1 * m_x1 + m_a2 * m_x2 - m_a3 * m_y1 - m_a4 * m_y2;
 
             // shift x1 to x2, sample to x1
-            x2 = x1;
-            x1 = inSample;
+            m_x2 = m_x1;
+            m_x1 = inSample;
 
             // shift y1 to y2, result to y1
-            y2 = y1;
-            y1 = static_cast<float>(result);
+            m_y2 = m_y1;
+            m_y1 = static_cast<float>(result);
 
-            return y1;
+            return m_y1;
         }
 
         void BiQuadFilter::setCoefficients(double aa0, double aa1, double aa2, double b0, double b1, double b2)
         {
+            if (CBuildConfig::isLocalDeveloperDebugBuild()) { BLACK_VERIFY_X(qAbs(aa0) > 1E-06, Q_FUNC_INFO, "Div by zero?"); }
+
             // precompute the coefficients
-            a0 = b0 / aa0;
-            a1 = b1 / aa0;
-            a2 = b2 / aa0;
-            a3 = aa1 / aa0;
-            a4 = aa2 / aa0;
+            m_a0 = b0 / aa0;
+            m_a1 = b1 / aa0;
+            m_a2 = b2 / aa0;
+            m_a3 = aa1 / aa0;
+            m_a4 = aa2 / aa0;
         }
 
         void BiQuadFilter::setLowPassFilter(float sampleRate, float cutoffFrequency, float q)
diff --git a/src/blacksound/dsp/biquadfilter.h b/src/blacksound/dsp/biquadfilter.h
index d0281d1c3..51c840bcc 100644
--- a/src/blacksound/dsp/biquadfilter.h
+++ b/src/blacksound/dsp/biquadfilter.h
@@ -8,8 +8,8 @@
 
 //! \file
 
-#ifndef BIQUADFILTER_H
-#define BIQUADFILTER_H
+#ifndef BLACKSOUND_DSP_BIQUADFILTER_H
+#define BLACKSOUND_DSP_BIQUADFILTER_H
 
 #include "blacksound/blacksoundexport.h"
 
@@ -24,28 +24,34 @@ namespace BlackSound
             //! Ctor
             BiQuadFilter() = default;
 
+            //! Transform
             float transform(float inSample);
+
+            //! Set filter parameters @{
             void setCoefficients(double aa0, double aa1, double aa2, double b0, double b1, double b2);
             void setLowPassFilter(float sampleRate, float cutoffFrequency, float q);
             void setPeakingEq(float sampleRate, float centreFrequency, float q, float dbGain);
             void setHighPassFilter(float sampleRate, float cutoffFrequency, float q);
+            //! @}
 
+            //! Get filters @{
             static BiQuadFilter lowPassFilter(float sampleRate, float cutoffFrequency, float q);
             static BiQuadFilter highPassFilter(float sampleRate, float cutoffFrequency, float q);
             static BiQuadFilter peakingEQ(float sampleRate, float centreFrequency, float q, float dbGain);
+            //! @}
 
         private:
-            double a0;
-            double a1;
-            double a2;
-            double a3;
-            double a4;
+            double m_a0 = 0.0;
+            double m_a1 = 0.0;
+            double m_a2 = 0.0;
+            double m_a3 = 0.0;
+            double m_a4 = 0.0;
 
             // state
-            float x1 = 0.0;
-            float x2 = 0.0;
-            float y1 = 0.0;
-            float y2 = 0.0;
+            float m_x1 = 0.0;
+            float m_x2 = 0.0;
+            float m_y1 = 0.0;
+            float m_y2 = 0.0;
         };
     } // ns
 } // ns