Clean up the biquad filter a bit

8 files changed, 49 insertions, 50 deletions

diff --git a/Alc/alu.cpp b/Alc/alu.cpp
index b4b34e5f..e30f6a2e 100644
--- a/Alc/alu.cpp
+++ b/Alc/alu.cpp
@@ -973,11 +973,11 @@ static void CalcPanningAndFilters(ALvoice *voice, const ALfloat Azi, const ALflo
         if(gainHF != 1.0f) voice->Direct.FilterType |= AF_LowPass;
         if(gainLF != 1.0f) voice->Direct.FilterType |= AF_HighPass;
         BiquadFilter_setParams(
-            &voice->Direct.Params[0].LowPass, BiquadType_HighShelf,
+            &voice->Direct.Params[0].LowPass, BiquadType::HighShelf,
             gainHF, hfScale, calc_rcpQ_from_slope(gainHF, 1.0f)
         );
         BiquadFilter_setParams(
-            &voice->Direct.Params[0].HighPass, BiquadType_LowShelf,
+            &voice->Direct.Params[0].HighPass, BiquadType::LowShelf,
             gainLF, lfScale, calc_rcpQ_from_slope(gainLF, 1.0f)
         );
         for(c = 1;c < num_channels;c++)
@@ -999,11 +999,11 @@ static void CalcPanningAndFilters(ALvoice *voice, const ALfloat Azi, const ALflo
         if(gainHF != 1.0f) voice->Send[i].FilterType |= AF_LowPass;
         if(gainLF != 1.0f) voice->Send[i].FilterType |= AF_HighPass;
         BiquadFilter_setParams(
-            &voice->Send[i].Params[0].LowPass, BiquadType_HighShelf,
+            &voice->Send[i].Params[0].LowPass, BiquadType::HighShelf,
             gainHF, hfScale, calc_rcpQ_from_slope(gainHF, 1.0f)
         );
         BiquadFilter_setParams(
-            &voice->Send[i].Params[0].HighPass, BiquadType_LowShelf,
+            &voice->Send[i].Params[0].HighPass, BiquadType::LowShelf,
             gainLF, lfScale, calc_rcpQ_from_slope(gainLF, 1.0f)
         );
         for(c = 1;c < num_channels;c++)
diff --git a/Alc/effects/distortion.cpp b/Alc/effects/distortion.cpp
index 31f07de3..69603db9 100644
--- a/Alc/effects/distortion.cpp
+++ b/Alc/effects/distortion.cpp
@@ -93,14 +93,14 @@ static ALvoid ALdistortionState_update(ALdistortionState *state, const ALCcontex
     /* Multiply sampling frequency by the amount of oversampling done during
      * processing.
      */
-    BiquadFilter_setParams(&state->lowpass, BiquadType_LowPass, 1.0f,
+    BiquadFilter_setParams(&state->lowpass, BiquadType::LowPass, 1.0f,
         cutoff / (frequency*4.0f), calc_rcpQ_from_bandwidth(cutoff / (frequency*4.0f), bandwidth)
     );
 
     cutoff = props->Distortion.EQCenter;
     /* Convert bandwidth in Hz to octaves. */
     bandwidth = props->Distortion.EQBandwidth / (cutoff * 0.67f);
-    BiquadFilter_setParams(&state->bandpass, BiquadType_BandPass, 1.0f,
+    BiquadFilter_setParams(&state->bandpass, BiquadType::BandPass, 1.0f,
         cutoff / (frequency*4.0f), calc_rcpQ_from_bandwidth(cutoff / (frequency*4.0f), bandwidth)
     );
 
diff --git a/Alc/effects/echo.cpp b/Alc/effects/echo.cpp
index 47d21e6c..946c07b4 100644
--- a/Alc/effects/echo.cpp
+++ b/Alc/effects/echo.cpp
@@ -136,7 +136,7 @@ static ALvoid ALechoState_update(ALechoState *state, const ALCcontext *context,
     state->FeedGain = props->Echo.Feedback;
 
     gainhf = maxf(1.0f - props->Echo.Damping, 0.0625f); /* Limit -24dB */
-    BiquadFilter_setParams(&state->Filter, BiquadType_HighShelf,
+    BiquadFilter_setParams(&state->Filter, BiquadType::HighShelf,
         gainhf, LOWPASSFREQREF/frequency, calc_rcpQ_from_slope(gainhf, 1.0f)
     );
 
diff --git a/Alc/effects/equalizer.cpp b/Alc/effects/equalizer.cpp
index 17eee5b4..ad101a7e 100644
--- a/Alc/effects/equalizer.cpp
+++ b/Alc/effects/equalizer.cpp
@@ -136,13 +136,13 @@ static ALvoid ALequalizerState_update(ALequalizerState *state, const ALCcontext
      */
     gain = maxf(sqrtf(props->Equalizer.LowGain), 0.0625f); /* Limit -24dB */
     f0norm = props->Equalizer.LowCutoff/frequency;
-    BiquadFilter_setParams(&state->Chans[0].filter[0], BiquadType_LowShelf,
+    BiquadFilter_setParams(&state->Chans[0].filter[0], BiquadType::LowShelf,
         gain, f0norm, calc_rcpQ_from_slope(gain, 0.75f)
     );
 
     gain = maxf(props->Equalizer.Mid1Gain, 0.0625f);
     f0norm = props->Equalizer.Mid1Center/frequency;
-    BiquadFilter_setParams(&state->Chans[0].filter[1], BiquadType_Peaking,
+    BiquadFilter_setParams(&state->Chans[0].filter[1], BiquadType::Peaking,
         gain, f0norm, calc_rcpQ_from_bandwidth(
             f0norm, props->Equalizer.Mid1Width
         )
@@ -150,7 +150,7 @@ static ALvoid ALequalizerState_update(ALequalizerState *state, const ALCcontext
 
     gain = maxf(props->Equalizer.Mid2Gain, 0.0625f);
     f0norm = props->Equalizer.Mid2Center/frequency;
-    BiquadFilter_setParams(&state->Chans[0].filter[2], BiquadType_Peaking,
+    BiquadFilter_setParams(&state->Chans[0].filter[2], BiquadType::Peaking,
         gain, f0norm, calc_rcpQ_from_bandwidth(
             f0norm, props->Equalizer.Mid2Width
         )
@@ -158,7 +158,7 @@ static ALvoid ALequalizerState_update(ALequalizerState *state, const ALCcontext
 
     gain = maxf(sqrtf(props->Equalizer.HighGain), 0.0625f);
     f0norm = props->Equalizer.HighCutoff/frequency;
-    BiquadFilter_setParams(&state->Chans[0].filter[3], BiquadType_HighShelf,
+    BiquadFilter_setParams(&state->Chans[0].filter[3], BiquadType::HighShelf,
         gain, f0norm, calc_rcpQ_from_slope(gain, 0.75f)
     );
 
diff --git a/Alc/effects/modulator.cpp b/Alc/effects/modulator.cpp
index e96859f7..b7ee97d9 100644
--- a/Alc/effects/modulator.cpp
+++ b/Alc/effects/modulator.cpp
@@ -152,7 +152,7 @@ static ALvoid ALmodulatorState_update(ALmodulatorState *state, const ALCcontext
     f0norm = props->Modulator.HighPassCutoff / (ALfloat)device->Frequency;
     f0norm = clampf(f0norm, 1.0f/512.0f, 0.49f);
     /* Bandwidth value is constant in octaves. */
-    BiquadFilter_setParams(&state->Chans[0].Filter, BiquadType_HighPass, 1.0f,
+    BiquadFilter_setParams(&state->Chans[0].Filter, BiquadType::HighPass, 1.0f,
                            f0norm, calc_rcpQ_from_bandwidth(f0norm, 0.75f));
     for(i = 1;i < MAX_EFFECT_CHANNELS;i++)
         BiquadFilter_copyParams(&state->Chans[i].Filter, &state->Chans[0].Filter);
diff --git a/Alc/effects/reverb.cpp b/Alc/effects/reverb.cpp
index d486e8b4..68c76337 100644
--- a/Alc/effects/reverb.cpp
+++ b/Alc/effects/reverb.cpp
@@ -728,9 +728,9 @@ static void CalcT60DampingCoeffs(const ALfloat length, const ALfloat lfDecayTime
     ALfloat hfGain = CalcDecayCoeff(length, hfDecayTime);
 
     filter->MidGain[1] = mfGain;
-    BiquadFilter_setParams(&filter->LFFilter, BiquadType_LowShelf, lfGain/mfGain, lf0norm,
+    BiquadFilter_setParams(&filter->LFFilter, BiquadType::LowShelf, lfGain/mfGain, lf0norm,
                            calc_rcpQ_from_slope(lfGain/mfGain, 1.0f));
-    BiquadFilter_setParams(&filter->HFFilter, BiquadType_HighShelf, hfGain/mfGain, hf0norm,
+    BiquadFilter_setParams(&filter->HFFilter, BiquadType::HighShelf, hfGain/mfGain, hf0norm,
                            calc_rcpQ_from_slope(hfGain/mfGain, 1.0f));
 }
 
@@ -964,11 +964,11 @@ static void ReverbState_update(ReverbState *State, const ALCcontext *Context, co
      * killing most of the signal.
      */
     gainhf = maxf(props->Reverb.GainHF, 0.001f);
-    BiquadFilter_setParams(&State->Filter[0].Lp, BiquadType_HighShelf, gainhf, hf0norm,
+    BiquadFilter_setParams(&State->Filter[0].Lp, BiquadType::HighShelf, gainhf, hf0norm,
                            calc_rcpQ_from_slope(gainhf, 1.0f));
     lf0norm = minf(props->Reverb.LFReference / frequency, 0.49f);
     gainlf = maxf(props->Reverb.GainLF, 0.001f);
-    BiquadFilter_setParams(&State->Filter[0].Hp, BiquadType_LowShelf, gainlf, lf0norm,
+    BiquadFilter_setParams(&State->Filter[0].Hp, BiquadType::LowShelf, gainlf, lf0norm,
                            calc_rcpQ_from_slope(gainlf, 1.0f));
     for(i = 1;i < NUM_LINES;i++)
     {
diff --git a/Alc/filters/defs.h b/Alc/filters/defs.h
index 58b7cc0a..19514b62 100644
--- a/Alc/filters/defs.h
+++ b/Alc/filters/defs.h
@@ -1,12 +1,11 @@
 #ifndef ALC_FILTER_H
 #define ALC_FILTER_H
 
+#include <cmath>
+
 #include "AL/al.h"
 #include "math_defs.h"
 
-#ifdef __cplusplus
-extern "C" {
-#endif
 
 /* Filters implementation is based on the "Cookbook formulae for audio
  * EQ biquad filter coefficients" by Robert Bristow-Johnson
@@ -18,28 +17,30 @@ extern "C" {
  * the square root of the desired linear gain (or halve the dB gain).
  */
 
-typedef enum BiquadType {
+enum class BiquadType {
     /** EFX-style low-pass filter, specifying a gain and reference frequency. */
-    BiquadType_HighShelf,
+    HighShelf,
     /** EFX-style high-pass filter, specifying a gain and reference frequency. */
-    BiquadType_LowShelf,
+    LowShelf,
     /** Peaking filter, specifying a gain and reference frequency. */
-    BiquadType_Peaking,
+    Peaking,
 
     /** Low-pass cut-off filter, specifying a cut-off frequency. */
-    BiquadType_LowPass,
+    LowPass,
     /** High-pass cut-off filter, specifying a cut-off frequency. */
-    BiquadType_HighPass,
+    HighPass,
     /** Band-pass filter, specifying a center frequency. */
-    BiquadType_BandPass,
-} BiquadType;
+    BandPass,
+};
 
-typedef struct BiquadFilter {
-    ALfloat z1, z2; /* Last two delayed components for direct form II. */
-    ALfloat b0, b1, b2; /* Transfer function coefficients "b" (numerator) */
-    ALfloat a1, a2; /* Transfer function coefficients "a" (denominator; a0 is
-                     * pre-applied). */
-} BiquadFilter;
+struct BiquadFilter {
+    /* Last two delayed components for direct form II. */
+    ALfloat z1{0.0f}, z2{0.0f};
+    /* Transfer function coefficients "b" (numerator) */
+    ALfloat b0{1.0f}, b1{0.0f}, b2{0.0f};
+    /* Transfer function coefficients "a" (denominator; a0 is pre-applied). */
+    ALfloat a1{0.0f}, a2{0.0f};
+};
 /* Currently only a C-based filter process method is implemented. */
 #define BiquadFilter_process BiquadFilter_processC
 
@@ -51,7 +52,7 @@ typedef struct BiquadFilter {
  */
 inline ALfloat calc_rcpQ_from_slope(ALfloat gain, ALfloat slope)
 {
-    return sqrtf((gain + 1.0f/gain)*(1.0f/slope - 1.0f) + 2.0f);
+    return std::sqrt((gain + 1.0f/gain)*(1.0f/slope - 1.0f) + 2.0f);
 }
 /**
  * Calculates the rcpQ (i.e. 1/Q) coefficient for filters, using the normalized
@@ -62,7 +63,7 @@ inline ALfloat calc_rcpQ_from_slope(ALfloat gain, ALfloat slope)
 inline ALfloat calc_rcpQ_from_bandwidth(ALfloat f0norm, ALfloat bandwidth)
 {
     ALfloat w0 = F_TAU * f0norm;
-    return 2.0f*sinhf(logf(2.0f)/2.0f*bandwidth*w0/sinf(w0));
+    return 2.0f*std::sinh(std::log(2.0f)/2.0f*bandwidth*w0/std::sin(w0));
 }
 
 inline void BiquadFilter_clear(BiquadFilter *filter)
@@ -113,8 +114,4 @@ inline void BiquadFilter_passthru(BiquadFilter *filter, ALsizei numsamples)
     }
 }
 
-#ifdef __cplusplus
-} // extern "C"
-#endif
-
 #endif /* ALC_FILTER_H */
diff --git a/Alc/filters/filter.cpp b/Alc/filters/filter.cpp
index 838a9a5d..6099cf13 100644
--- a/Alc/filters/filter.cpp
+++ b/Alc/filters/filter.cpp
@@ -1,6 +1,8 @@
 
 #include "config.h"
 
+#include <cmath>
+
 #include "AL/alc.h"
 #include "AL/al.h"
 
@@ -19,15 +21,15 @@ void BiquadFilter_setParams(BiquadFilter *filter, BiquadType type, ALfloat gain,
     assert(gain > 0.00001f);
 
     w0 = F_TAU * f0norm;
-    sin_w0 = sinf(w0);
-    cos_w0 = cosf(w0);
+    sin_w0 = std::sin(w0);
+    cos_w0 = std::cos(w0);
     alpha = sin_w0/2.0f * rcpQ;
 
     /* Calculate filter coefficients depending on filter type */
     switch(type)
     {
-        case BiquadType_HighShelf:
-            sqrtgain_alpha_2 = 2.0f * sqrtf(gain) * alpha;
+        case BiquadType::HighShelf:
+            sqrtgain_alpha_2 = 2.0f * std::sqrt(gain) * alpha;
             b[0] =       gain*((gain+1.0f) + (gain-1.0f)*cos_w0 + sqrtgain_alpha_2);
             b[1] = -2.0f*gain*((gain-1.0f) + (gain+1.0f)*cos_w0                   );
             b[2] =       gain*((gain+1.0f) + (gain-1.0f)*cos_w0 - sqrtgain_alpha_2);
@@ -35,8 +37,8 @@ void BiquadFilter_setParams(BiquadFilter *filter, BiquadType type, ALfloat gain,
             a[1] =  2.0f*     ((gain-1.0f) - (gain+1.0f)*cos_w0                   );
             a[2] =             (gain+1.0f) - (gain-1.0f)*cos_w0 - sqrtgain_alpha_2;
             break;
-        case BiquadType_LowShelf:
-            sqrtgain_alpha_2 = 2.0f * sqrtf(gain) * alpha;
+        case BiquadType::LowShelf:
+            sqrtgain_alpha_2 = 2.0f * std::sqrt(gain) * alpha;
             b[0] =       gain*((gain+1.0f) - (gain-1.0f)*cos_w0 + sqrtgain_alpha_2);
             b[1] =  2.0f*gain*((gain-1.0f) - (gain+1.0f)*cos_w0                   );
             b[2] =       gain*((gain+1.0f) - (gain-1.0f)*cos_w0 - sqrtgain_alpha_2);
@@ -44,8 +46,8 @@ void BiquadFilter_setParams(BiquadFilter *filter, BiquadType type, ALfloat gain,
             a[1] = -2.0f*     ((gain-1.0f) + (gain+1.0f)*cos_w0                   );
             a[2] =             (gain+1.0f) + (gain-1.0f)*cos_w0 - sqrtgain_alpha_2;
             break;
-        case BiquadType_Peaking:
-            gain = sqrtf(gain);
+        case BiquadType::Peaking:
+            gain = std::sqrt(gain);
             b[0] =  1.0f + alpha * gain;
             b[1] = -2.0f * cos_w0;
             b[2] =  1.0f - alpha * gain;
@@ -54,7 +56,7 @@ void BiquadFilter_setParams(BiquadFilter *filter, BiquadType type, ALfloat gain,
             a[2] =  1.0f - alpha / gain;
             break;
 
-        case BiquadType_LowPass:
+        case BiquadType::LowPass:
             b[0] = (1.0f - cos_w0) / 2.0f;
             b[1] =  1.0f - cos_w0;
             b[2] = (1.0f - cos_w0) / 2.0f;
@@ -62,7 +64,7 @@ void BiquadFilter_setParams(BiquadFilter *filter, BiquadType type, ALfloat gain,
             a[1] = -2.0f * cos_w0;
             a[2] =  1.0f - alpha;
             break;
-        case BiquadType_HighPass:
+        case BiquadType::HighPass:
             b[0] =  (1.0f + cos_w0) / 2.0f;
             b[1] = -(1.0f + cos_w0);
             b[2] =  (1.0f + cos_w0) / 2.0f;
@@ -70,7 +72,7 @@ void BiquadFilter_setParams(BiquadFilter *filter, BiquadType type, ALfloat gain,
             a[1] =  -2.0f * cos_w0;
             a[2] =   1.0f - alpha;
             break;
-        case BiquadType_BandPass:
+        case BiquadType::BandPass:
             b[0] =  alpha;
             b[1] =  0;
             b[2] = -alpha;