Use ALfilterState for the source direct and send filters

5 files changed, 37 insertions, 31 deletions

diff --git a/Alc/ALu.c b/Alc/ALu.c
index 4d6c46da..70b5c80a 100644
--- a/Alc/ALu.c
+++ b/Alc/ALu.c
@@ -254,8 +254,6 @@ ALvoid CalcNonAttnSourceParams(ALsource *ALSource, const ALCcontext *ALContext)
     ALboolean DirectChannels;
     ALfloat hwidth = 0.0f;
     ALfloat Pitch;
-    ALfloat coeff;
-    ALfloat cw;
     ALint i, c;
 
     /* Get device properties */
@@ -453,21 +451,20 @@ ALvoid CalcNonAttnSourceParams(ALsource *ALSource, const ALCcontext *ALContext)
         ALSource->Params.Send[i].Gain = WetGain[i];
     }
 
-    /* Update filter coefficients. Calculations based on the I3DL2
-     * spec. */
-    cw = cosf(F_PI*2.0f * LOWPASSFREQREF / Frequency);
-
-    /* We use two chained one-pole filters, so we need to take the
-     * square root of the squared gain, which is the same as the base
-     * gain. */
-    coeff = lpCoeffCalc(DryGainHF, cw);
-    for(c = 0;c < num_channels;c++)
-        ALSource->Params.Direct.Filter[c].coeff = lpCoeffCalc(DryGainHF, cw);
+    {
+        ALfloat gain = maxf(0.001f, DryGainHF);
+        for(c = 0;c < num_channels;c++)
+            ALfilterState_setParams(&ALSource->Params.Direct.Filter[c],
+                                    ALfilterType_LowPass, gain,
+                                    (ALfloat)LOWPASSFREQREF/Frequency, 0.0f);
+    }
     for(i = 0;i < NumSends;i++)
     {
-        coeff = lpCoeffCalc(WetGainHF[i], cw);
+        ALfloat gain = maxf(0.001f, WetGainHF[i]);
         for(c = 0;c < num_channels;c++)
-            ALSource->Params.Send[i].Filter[c].coeff = coeff;
+            ALfilterState_setParams(&ALSource->Params.Send[i].Filter[c],
+                                    ALfilterType_LowPass, gain,
+                                    (ALfloat)LOWPASSFREQREF/Frequency, 0.0f);
     }
 }
 
@@ -499,7 +496,6 @@ ALvoid CalcSourceParams(ALsource *ALSource, const ALCcontext *ALContext)
     ALfloat Pitch;
     ALuint Frequency;
     ALint NumSends;
-    ALfloat cw;
     ALint i, j;
 
     DryGainHF = 1.0f;
@@ -904,15 +900,14 @@ ALvoid CalcSourceParams(ALsource *ALSource, const ALCcontext *ALContext)
     for(i = 0;i < NumSends;i++)
         ALSource->Params.Send[i].Gain = WetGain[i];
 
-    /* Update filter coefficients. */
-    cw = cosf(F_PI*2.0f * LOWPASSFREQREF / Frequency);
 
-    ALSource->Params.Direct.Filter[0].coeff = lpCoeffCalc(DryGainHF, cw);
+    ALfilterState_setParams(&ALSource->Params.Direct.Filter[0],
+                            ALfilterType_LowPass, maxf(0.001f, DryGainHF),
+                            (ALfloat)LOWPASSFREQREF/Frequency, 0.0f);
     for(i = 0;i < NumSends;i++)
-    {
-        ALfloat a = lpCoeffCalc(WetGainHF[i], cw);
-        ALSource->Params.Send[i].Filter[0].coeff = a;
-    }
+        ALfilterState_setParams(&ALSource->Params.Send[i].Filter[0],
+                                ALfilterType_LowPass, maxf(0.001f, WetGainHF[i]),
+                                (ALfloat)LOWPASSFREQREF/Frequency, 0.0f);
 }
 
 
diff --git a/Alc/mixer.c b/Alc/mixer.c
index 58e3a535..b9dcc1c1 100644
--- a/Alc/mixer.c
+++ b/Alc/mixer.c
@@ -84,13 +84,13 @@ static void SilenceData(ALfloat *dst, ALuint samples)
 }
 
 
-static void Filter2P(FILTER *filter, ALfloat *restrict dst, const ALfloat *restrict src,
+static void DoFilter(ALfilterState *filter, ALfloat *restrict dst, const ALfloat *restrict src,
                      ALuint numsamples)
 {
     ALuint i;
     for(i = 0;i < numsamples;i++)
-        dst[i] = lpFilter2P(filter, src[i]);
-    dst[i] = lpFilter2PC(filter, src[i]);
+        dst[i] = ALfilterState_processSingle(filter, src[i]);
+    dst[i] = ALfilterState_processSingleC(filter, src[i]);
 }
 
 
@@ -328,7 +328,7 @@ ALvoid MixSource(ALsource *Source, ALCdevice *Device, ALuint SamplesToDo)
             {
                 DirectParams *directparms = &Source->Params.Direct;
 
-                Filter2P(&directparms->Filter[chan], SrcData, ResampledData,
+                DoFilter(&directparms->Filter[chan], SrcData, ResampledData,
                          DstBufferSize);
                 Source->Params.DryMix(directparms, SrcData, chan, OutPos,
                                       SamplesToDo, DstBufferSize);
@@ -340,7 +340,7 @@ ALvoid MixSource(ALsource *Source, ALCdevice *Device, ALuint SamplesToDo)
                 if(!sendparms->Slot)
                     continue;
 
-                Filter2P(&sendparms->Filter[chan], SrcData, ResampledData,
+                DoFilter(&sendparms->Filter[chan], SrcData, ResampledData,
                          DstBufferSize);
                 Source->Params.WetMix(sendparms, SrcData, OutPos,
                                       SamplesToDo, DstBufferSize);
diff --git a/OpenAL32/Include/alFilter.h b/OpenAL32/Include/alFilter.h
index f70b839e..9273f15c 100644
--- a/OpenAL32/Include/alFilter.h
+++ b/OpenAL32/Include/alFilter.h
@@ -47,6 +47,8 @@ ALfloat lpCoeffCalc(ALfloat g, ALfloat cw);
 
 
 typedef enum ALfilterType {
+    ALfilterType_LowPass,
+
     ALfilterType_HighShelf,
     ALfilterType_LowShelf,
     ALfilterType_Peaking,
diff --git a/OpenAL32/Include/alSource.h b/OpenAL32/Include/alSource.h
index bd1b2931..8766c85e 100644
--- a/OpenAL32/Include/alSource.h
+++ b/OpenAL32/Include/alSource.h
@@ -61,8 +61,7 @@ typedef struct DirectParams {
      * target (eg. FrontLeft). Not used with HRTF. */
     ALfloat Gains[MaxChannels][MaxChannels];
 
-    /* A low-pass filter, using 2 chained one-pole filters. */
-    FILTER Filter[MaxChannels];
+    ALfilterState Filter[MaxChannels];
 } DirectParams;
 
 typedef struct SendParams {
@@ -72,8 +71,7 @@ typedef struct SendParams {
      * output buffer. */
     ALfloat Gain;
 
-    /* A low-pass filter, using 2 chained one-pole filters. */
-    FILTER Filter[MaxChannels];
+    ALfilterState Filter[MaxChannels];
 } SendParams;
 
 
diff --git a/OpenAL32/alFilter.c b/OpenAL32/alFilter.c
index 5bef87fd..550c99f5 100644
--- a/OpenAL32/alFilter.c
+++ b/OpenAL32/alFilter.c
@@ -343,6 +343,17 @@ void ALfilterState_setParams(ALfilterState *filter, ALfilterType type, ALfloat g
     /* Calculate filter coefficients depending on filter type */
     switch(type)
     {
+        case ALfilterType_LowPass:
+            alpha = sinf(w0) / 2.0f * sqrtf((gain + 1.0f/gain) *
+                                            (1.0f/0.75f - 1.0f) + 2.0f);
+            filter->b[0] = (1.0f - cosf(w0)) * 0.5f;
+            filter->b[1] =  1.0f - cosf(w0);
+            filter->b[2] = (1.0f - cosf(w0)) * 0.5f;
+            filter->a[0] =  1.0f + alpha;
+            filter->a[1] = -2.0f*cosf(w0);
+            filter->a[2] =  1.0f - alpha;
+            break;
+
         case ALfilterType_HighShelf:
             alpha = sinf(w0) / 2.0f * sqrtf((gain + 1.0f/gain) *
                                             (1.0f/0.75f - 1.0f) + 2.0f);