3 files changed, 14 insertions, 2 deletions
diff --git a/OpenAL32/Include/alAuxEffectSlot.h b/OpenAL32/Include/alAuxEffectSlot.h
index d4cb0d11..9bae788d 100644
--- a/OpenAL32/Include/alAuxEffectSlot.h
+++ b/OpenAL32/Include/alAuxEffectSlot.h
@@ -1,8 +1,9 @@
 #ifndef _AL_AUXEFFECTSLOT_H_
 #define _AL_AUXEFFECTSLOT_H_
 
-#include "alEffect.h"
 #include "AL/al.h"
+#include "alEffect.h"
+#include "alFilter.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -28,7 +29,8 @@ typedef struct ALeffectslot
     ALuint ReverbReflectPos;
     ALuint ReverbLatePos;
     ALfloat ReverbDecayGain;
-    ALfloat LastDecaySample;
+
+    FILTER iirFilter;
 
     ALuint refcount;
 
diff --git a/OpenAL32/Include/alFilter.h b/OpenAL32/Include/alFilter.h
index 038304e8..f1d24d0f 100644
--- a/OpenAL32/Include/alFilter.h
+++ b/OpenAL32/Include/alFilter.h
@@ -7,6 +7,11 @@
 extern "C" {
 #endif
 
+typedef struct {
+    float *history; /* pointer to history in filter */
+    float *coef;    /* pointer to coefficients of filter */
+} FILTER;
+
 #define AL_FILTER_TYPE                                     0x8001
 
 #define AL_FILTER_NULL                                     0x0000
@@ -48,6 +53,9 @@ AL_API ALvoid AL_APIENTRY alGetFilterfv(ALuint filter, ALenum param, ALfloat *pf
 
 ALvoid ReleaseALFilters(ALvoid);
 
+float lpFilter(FILTER *iir, float input);
+int InitLowPassFilter(ALCcontext *Context, FILTER *iir);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/OpenAL32/Include/alSource.h b/OpenAL32/Include/alSource.h
index 1d3fc57c..73b02609 100644
--- a/OpenAL32/Include/alSource.h
+++ b/OpenAL32/Include/alSource.h
@@ -75,6 +75,8 @@ typedef struct ALsource
     ALboolean WetGainHFAuto;
     ALfloat   OuterGainHF;
 
+    FILTER iirFilter;
+
     ALfloat AirAbsorptionFactor;
 
     ALfloat RoomRolloffFactor;