Use some macros to help with deriving types

9 files changed, 85 insertions, 93 deletions

diff --git a/Alc/alcChorus.c b/Alc/alcChorus.c
index 5a25d4d1..6a56cf68 100644
--- a/Alc/alcChorus.c
+++ b/Alc/alcChorus.c
@@ -31,8 +31,7 @@
 
 
 typedef struct ALchorusState {
-    // Must be first in all effects!
-    ALeffectState state;
+    DERIVE_FROM_TYPE(ALeffectState);
 
     ALfloat *SampleBufferLeft;
     ALfloat *SampleBufferRight;
@@ -56,8 +55,7 @@ typedef struct ALchorusState {
 
 static ALvoid ChorusDestroy(ALeffectState *effect)
 {
-    ALchorusState *state = (ALchorusState*)effect;
-
+    ALchorusState *state = GET_PARENT_TYPE(ALchorusState, ALeffectState, effect);
     if(state)
     {
         free(state->SampleBufferLeft);
@@ -72,7 +70,7 @@ static ALvoid ChorusDestroy(ALeffectState *effect)
 
 static ALboolean ChorusDeviceUpdate(ALeffectState *effect, ALCdevice *Device)
 {
-    ALchorusState *state = (ALchorusState*)effect;
+    ALchorusState *state = GET_PARENT_TYPE(ALchorusState, ALeffectState, effect);
     ALuint maxlen;
     ALuint it;
 
@@ -113,7 +111,7 @@ static ALboolean ChorusDeviceUpdate(ALeffectState *effect, ALCdevice *Device)
 
 static ALvoid ChorusUpdate(ALeffectState *effect, ALCdevice *Device, const ALeffectslot *Slot)
 {
-    ALchorusState *state = (ALchorusState*)effect;
+    ALchorusState *state = GET_PARENT_TYPE(ALchorusState, ALeffectState, effect);
     ALuint it;
 
     for (it = 0; it < MaxChannels; it++)
@@ -173,7 +171,7 @@ static ALvoid ChorusUpdate(ALeffectState *effect, ALCdevice *Device, const ALeff
 
 static ALvoid ChorusProcess(ALeffectState *effect, ALuint SamplesToDo, const ALfloat *RESTRICT SamplesIn, ALfloat (*RESTRICT SamplesOut)[BUFFERSIZE])
 {
-    ALchorusState *state = (ALchorusState*)effect;
+    ALchorusState *state = GET_PARENT_TYPE(ALchorusState, ALeffectState, effect);
     const ALuint mask = state->BufferLength-1;
     ALuint it;
     ALuint kt;
@@ -257,17 +255,17 @@ ALeffectState *ChorusCreate(void)
     if(!state)
         return NULL;
 
-    state->state.Destroy = ChorusDestroy;
-    state->state.DeviceUpdate = ChorusDeviceUpdate;
-    state->state.Update = ChorusUpdate;
-    state->state.Process = ChorusProcess;
+    GET_DERIVED_TYPE(ALeffectState, state)->Destroy = ChorusDestroy;
+    GET_DERIVED_TYPE(ALeffectState, state)->DeviceUpdate = ChorusDeviceUpdate;
+    GET_DERIVED_TYPE(ALeffectState, state)->Update = ChorusUpdate;
+    GET_DERIVED_TYPE(ALeffectState, state)->Process = ChorusProcess;
 
     state->BufferLength = 0;
     state->SampleBufferLeft = NULL;
     state->SampleBufferRight = NULL;
     state->offset = 0;
 
-    return &state->state;
+    return GET_DERIVED_TYPE(ALeffectState, state);
 }
 
 void chorus_SetParami(ALeffect *effect, ALCcontext *context, ALenum param, ALint val)
diff --git a/Alc/alcDedicated.c b/Alc/alcDedicated.c
index d73d8959..e10ad9e9 100644
--- a/Alc/alcDedicated.c
+++ b/Alc/alcDedicated.c
@@ -30,8 +30,7 @@
 
 
 typedef struct ALdedicatedState {
-    // Must be first in all effects!
-    ALeffectState state;
+    DERIVE_FROM_TYPE(ALeffectState);
 
     ALfloat gains[MaxChannels];
 } ALdedicatedState;
@@ -39,7 +38,7 @@ typedef struct ALdedicatedState {
 
 static ALvoid DedicatedDestroy(ALeffectState *effect)
 {
-    ALdedicatedState *state = (ALdedicatedState*)effect;
+    ALdedicatedState *state = GET_PARENT_TYPE(ALdedicatedState, ALeffectState, effect);
     free(state);
 }
 
@@ -52,7 +51,7 @@ static ALboolean DedicatedDeviceUpdate(ALeffectState *effect, ALCdevice *Device)
 
 static ALvoid DedicatedUpdate(ALeffectState *effect, ALCdevice *device, const ALeffectslot *Slot)
 {
-    ALdedicatedState *state = (ALdedicatedState*)effect;
+    ALdedicatedState *state = GET_PARENT_TYPE(ALdedicatedState, ALeffectState, effect);
     ALfloat Gain;
     ALsizei s;
 
@@ -68,7 +67,7 @@ static ALvoid DedicatedUpdate(ALeffectState *effect, ALCdevice *device, const AL
 
 static ALvoid DedicatedProcess(ALeffectState *effect, ALuint SamplesToDo, const ALfloat *RESTRICT SamplesIn, ALfloat (*RESTRICT SamplesOut)[BUFFERSIZE])
 {
-    ALdedicatedState *state = (ALdedicatedState*)effect;
+    ALdedicatedState *state = GET_PARENT_TYPE(ALdedicatedState, ALeffectState, effect);
     const ALfloat *gains = state->gains;
     ALuint i, c;
 
@@ -88,15 +87,15 @@ ALeffectState *DedicatedCreate(void)
     if(!state)
         return NULL;
 
-    state->state.Destroy = DedicatedDestroy;
-    state->state.DeviceUpdate = DedicatedDeviceUpdate;
-    state->state.Update = DedicatedUpdate;
-    state->state.Process = DedicatedProcess;
+    GET_DERIVED_TYPE(ALeffectState, state)->Destroy = DedicatedDestroy;
+    GET_DERIVED_TYPE(ALeffectState, state)->DeviceUpdate = DedicatedDeviceUpdate;
+    GET_DERIVED_TYPE(ALeffectState, state)->Update = DedicatedUpdate;
+    GET_DERIVED_TYPE(ALeffectState, state)->Process = DedicatedProcess;
 
     for(s = 0;s < MaxChannels;s++)
         state->gains[s] = 0.0f;
 
-    return &state->state;
+    return GET_DERIVED_TYPE(ALeffectState, state);
 }
 
 void ded_SetParami(ALeffect *effect, ALCcontext *context, ALenum param, ALint val)
diff --git a/Alc/alcDistortion.c b/Alc/alcDistortion.c
index 59ccca73..05833680 100644
--- a/Alc/alcDistortion.c
+++ b/Alc/alcDistortion.c
@@ -47,8 +47,7 @@ typedef struct ALEQFilter {
 } ALEQFilter;
 
 typedef struct ALdistortionState {
-    /* Must be first in all effects! */
-    ALeffectState state;
+    DERIVE_FROM_TYPE(ALeffectState);
 
     /* Effect gains for each channel */
     ALfloat Gain[MaxChannels];
@@ -66,14 +65,13 @@ typedef struct ALdistortionState {
 
 static ALvoid DistortionDestroy(ALeffectState *effect)
 {
-    ALdistortionState *state = (ALdistortionState*)effect;
-
+    ALdistortionState *state = GET_PARENT_TYPE(ALdistortionState, ALeffectState, effect);
     free(state);
 }
 
 static ALboolean DistortionDeviceUpdate(ALeffectState *effect, ALCdevice *Device)
 {
-    ALdistortionState *state = (ALdistortionState*)effect;
+    ALdistortionState *state = GET_PARENT_TYPE(ALdistortionState, ALeffectState, effect);
 
     state->frequency = (ALfloat)Device->Frequency;
 
@@ -82,7 +80,7 @@ static ALboolean DistortionDeviceUpdate(ALeffectState *effect, ALCdevice *Device
 
 static ALvoid DistortionUpdate(ALeffectState *effect, ALCdevice *Device, const ALeffectslot *Slot)
 {
-    ALdistortionState *state = (ALdistortionState*)effect;
+    ALdistortionState *state = GET_PARENT_TYPE(ALdistortionState, ALeffectState, effect);
     ALfloat gain = sqrtf(1.0f / Device->NumChan) * Slot->Gain;
     ALuint it;
     ALfloat w0;
@@ -135,7 +133,7 @@ static ALvoid DistortionUpdate(ALeffectState *effect, ALCdevice *Device, const A
 
 static ALvoid DistortionProcess(ALeffectState *effect, ALuint SamplesToDo, const ALfloat *RESTRICT SamplesIn, ALfloat (*RESTRICT SamplesOut)[BUFFERSIZE])
 {
-    ALdistortionState *state = (ALdistortionState*)effect;
+    ALdistortionState *state = GET_PARENT_TYPE(ALdistortionState, ALeffectState, effect);
     float *RESTRICT oversample_buffer = &state->oversample_buffer[0][0];
     ALfloat tempsmp;
     ALuint it;
@@ -222,10 +220,10 @@ ALeffectState *DistortionCreate(void)
     if(!state)
         return NULL;
 
-    state->state.Destroy = DistortionDestroy;
-    state->state.DeviceUpdate = DistortionDeviceUpdate;
-    state->state.Update = DistortionUpdate;
-    state->state.Process = DistortionProcess;
+    GET_DERIVED_TYPE(ALeffectState, state)->Destroy = DistortionDestroy;
+    GET_DERIVED_TYPE(ALeffectState, state)->DeviceUpdate = DistortionDeviceUpdate;
+    GET_DERIVED_TYPE(ALeffectState, state)->Update = DistortionUpdate;
+    GET_DERIVED_TYPE(ALeffectState, state)->Process = DistortionProcess;
 
     state->bandpass.type = BANDPASS;
     state->lowpass.type = LOWPASS;
@@ -237,7 +235,7 @@ ALeffectState *DistortionCreate(void)
     state->lowpass.y[0] = 0.0f;
     state->lowpass.y[1] = 0.0f;
 
-    return &state->state;
+    return GET_DERIVED_TYPE(ALeffectState, state);
 }
 
 void distortion_SetParami(ALeffect *effect, ALCcontext *context, ALenum param, ALint val)
diff --git a/Alc/alcEcho.c b/Alc/alcEcho.c
index 55a5b599..1d06e68a 100644
--- a/Alc/alcEcho.c
+++ b/Alc/alcEcho.c
@@ -31,8 +31,7 @@
 
 
 typedef struct ALechoState {
-    // Must be first in all effects!
-    ALeffectState state;
+    DERIVE_FROM_TYPE(ALeffectState);
 
     ALfloat *SampleBuffer;
     ALuint BufferLength;
@@ -54,7 +53,7 @@ typedef struct ALechoState {
 
 static ALvoid EchoDestroy(ALeffectState *effect)
 {
-    ALechoState *state = (ALechoState*)effect;
+    ALechoState *state = GET_PARENT_TYPE(ALechoState, ALeffectState, effect);
     if(state)
     {
         free(state->SampleBuffer);
@@ -65,7 +64,7 @@ static ALvoid EchoDestroy(ALeffectState *effect)
 
 static ALboolean EchoDeviceUpdate(ALeffectState *effect, ALCdevice *Device)
 {
-    ALechoState *state = (ALechoState*)effect;
+    ALechoState *state = GET_PARENT_TYPE(ALechoState, ALeffectState, effect);
     ALuint maxlen, i;
 
     // Use the next power of 2 for the buffer length, so the tap offsets can be
@@ -92,7 +91,7 @@ static ALboolean EchoDeviceUpdate(ALeffectState *effect, ALCdevice *Device)
 
 static ALvoid EchoUpdate(ALeffectState *effect, ALCdevice *Device, const ALeffectslot *Slot)
 {
-    ALechoState *state = (ALechoState*)effect;
+    ALechoState *state = GET_PARENT_TYPE(ALechoState, ALeffectState, effect);
     ALuint frequency = Device->Frequency;
     ALfloat lrpan, cw, g, gain;
     ALfloat dirGain;
@@ -128,7 +127,7 @@ static ALvoid EchoUpdate(ALeffectState *effect, ALCdevice *Device, const ALeffec
 
 static ALvoid EchoProcess(ALeffectState *effect, ALuint SamplesToDo, const ALfloat *RESTRICT SamplesIn, ALfloat (*RESTRICT SamplesOut)[BUFFERSIZE])
 {
-    ALechoState *state = (ALechoState*)effect;
+    ALechoState *state = GET_PARENT_TYPE(ALechoState, ALeffectState, effect);
     const ALuint mask = state->BufferLength-1;
     const ALuint tap1 = state->Tap[0].delay;
     const ALuint tap2 = state->Tap[1].delay;
@@ -164,10 +163,10 @@ ALeffectState *EchoCreate(void)
     if(!state)
         return NULL;
 
-    state->state.Destroy = EchoDestroy;
-    state->state.DeviceUpdate = EchoDeviceUpdate;
-    state->state.Update = EchoUpdate;
-    state->state.Process = EchoProcess;
+    GET_DERIVED_TYPE(ALeffectState, state)->Destroy = EchoDestroy;
+    GET_DERIVED_TYPE(ALeffectState, state)->DeviceUpdate = EchoDeviceUpdate;
+    GET_DERIVED_TYPE(ALeffectState, state)->Update = EchoUpdate;
+    GET_DERIVED_TYPE(ALeffectState, state)->Process = EchoProcess;
 
     state->BufferLength = 0;
     state->SampleBuffer = NULL;
@@ -180,7 +179,7 @@ ALeffectState *EchoCreate(void)
     state->iirFilter.history[0] = 0.0f;
     state->iirFilter.history[1] = 0.0f;
 
-    return &state->state;
+    return GET_DERIVED_TYPE(ALeffectState, state);
 }
 
 void echo_SetParami(ALeffect *effect, ALCcontext *context, ALenum param, ALint val)
diff --git a/Alc/alcEqualizer.c b/Alc/alcEqualizer.c
index dffc431a..c10eba2a 100644
--- a/Alc/alcEqualizer.c
+++ b/Alc/alcEqualizer.c
@@ -85,8 +85,7 @@ typedef struct ALEQFilter {
 } ALEQFilter;
 
 typedef struct ALequalizerState {
-    /* Must be first in all effects! */
-    ALeffectState state;
+    DERIVE_FROM_TYPE(ALeffectState);
 
     /* Effect gains for each channel */
     ALfloat Gain[MaxChannels];
@@ -98,14 +97,13 @@ typedef struct ALequalizerState {
 
 static ALvoid EqualizerDestroy(ALeffectState *effect)
 {
-    ALequalizerState *state = (ALequalizerState*)effect;
-
+    ALequalizerState *state = GET_PARENT_TYPE(ALequalizerState, ALeffectState, effect);
     free(state);
 }
 
 static ALboolean EqualizerDeviceUpdate(ALeffectState *effect, ALCdevice *Device)
 {
-    ALequalizerState *state = (ALequalizerState*)effect;
+    ALequalizerState *state = GET_PARENT_TYPE(ALequalizerState, ALeffectState, effect);
 
     state->frequency = (ALfloat)Device->Frequency;
 
@@ -114,7 +112,7 @@ static ALboolean EqualizerDeviceUpdate(ALeffectState *effect, ALCdevice *Device)
 
 static ALvoid EqualizerUpdate(ALeffectState *effect, ALCdevice *Device, const ALeffectslot *Slot)
 {
-    ALequalizerState *state = (ALequalizerState*)effect;
+    ALequalizerState *state = GET_PARENT_TYPE(ALequalizerState, ALeffectState, effect);
     ALfloat gain = sqrtf(1.0f / Device->NumChan) * Slot->Gain;
     ALuint it;
 
@@ -215,7 +213,7 @@ static ALvoid EqualizerUpdate(ALeffectState *effect, ALCdevice *Device, const AL
 
 static ALvoid EqualizerProcess(ALeffectState *effect, ALuint SamplesToDo, const ALfloat *RESTRICT SamplesIn, ALfloat (*RESTRICT SamplesOut)[BUFFERSIZE])
 {
-    ALequalizerState *state = (ALequalizerState*)effect;
+    ALequalizerState *state = GET_PARENT_TYPE(ALequalizerState, ALeffectState, effect);
     ALuint it;
     ALuint kt;
     ALuint ft;
@@ -254,10 +252,10 @@ ALeffectState *EqualizerCreate(void)
     if(!state)
         return NULL;
 
-    state->state.Destroy = EqualizerDestroy;
-    state->state.DeviceUpdate = EqualizerDeviceUpdate;
-    state->state.Update = EqualizerUpdate;
-    state->state.Process = EqualizerProcess;
+    GET_DERIVED_TYPE(ALeffectState, state)->Destroy = EqualizerDestroy;
+    GET_DERIVED_TYPE(ALeffectState, state)->DeviceUpdate = EqualizerDeviceUpdate;
+    GET_DERIVED_TYPE(ALeffectState, state)->Update = EqualizerUpdate;
+    GET_DERIVED_TYPE(ALeffectState, state)->Process = EqualizerProcess;
 
     state->bandfilter[0].type = LOW_SHELF;
     state->bandfilter[1].type = PEAKING;
@@ -274,7 +272,7 @@ ALeffectState *EqualizerCreate(void)
         state->bandfilter[it].y[1] = 0.0f;
     }
 
-    return &state->state;
+    return GET_DERIVED_TYPE(ALeffectState, state);
 }
 
 void equalizer_SetParami(ALeffect *effect, ALCcontext *context, ALenum param, ALint val)
diff --git a/Alc/alcFlanger.c b/Alc/alcFlanger.c
index d5764706..5b643a46 100644
--- a/Alc/alcFlanger.c
+++ b/Alc/alcFlanger.c
@@ -31,8 +31,7 @@
 
 
 typedef struct ALflangerState {
-    // Must be first in all effects!
-    ALeffectState state;
+    DERIVE_FROM_TYPE(ALeffectState);
 
     ALfloat *SampleBufferLeft;
     ALfloat *SampleBufferRight;
@@ -56,8 +55,7 @@ typedef struct ALflangerState {
 
 static ALvoid FlangerDestroy(ALeffectState *effect)
 {
-    ALflangerState *state = (ALflangerState*)effect;
-
+    ALflangerState *state = GET_PARENT_TYPE(ALflangerState, ALeffectState, effect);
     if(state)
     {
         free(state->SampleBufferLeft);
@@ -72,7 +70,7 @@ static ALvoid FlangerDestroy(ALeffectState *effect)
 
 static ALboolean FlangerDeviceUpdate(ALeffectState *effect, ALCdevice *Device)
 {
-    ALflangerState *state = (ALflangerState*)effect;
+    ALflangerState *state = GET_PARENT_TYPE(ALflangerState, ALeffectState, effect);
     ALuint maxlen;
     ALuint it;
 
@@ -113,7 +111,7 @@ static ALboolean FlangerDeviceUpdate(ALeffectState *effect, ALCdevice *Device)
 
 static ALvoid FlangerUpdate(ALeffectState *effect, ALCdevice *Device, const ALeffectslot *Slot)
 {
-    ALflangerState *state = (ALflangerState*)effect;
+    ALflangerState *state = GET_PARENT_TYPE(ALflangerState, ALeffectState, effect);
     ALuint it;
 
     for (it = 0; it < MaxChannels; it++)
@@ -173,7 +171,7 @@ static ALvoid FlangerUpdate(ALeffectState *effect, ALCdevice *Device, const ALef
 
 static ALvoid FlangerProcess(ALeffectState *effect, ALuint SamplesToDo, const ALfloat *RESTRICT SamplesIn, ALfloat (*RESTRICT SamplesOut)[BUFFERSIZE])
 {
-    ALflangerState *state = (ALflangerState*)effect;
+    ALflangerState *state = GET_PARENT_TYPE(ALflangerState, ALeffectState, effect);
     const ALuint mask = state->BufferLength-1;
     ALuint it;
     ALuint kt;
@@ -257,17 +255,17 @@ ALeffectState *FlangerCreate(void)
     if(!state)
         return NULL;
 
-    state->state.Destroy = FlangerDestroy;
-    state->state.DeviceUpdate = FlangerDeviceUpdate;
-    state->state.Update = FlangerUpdate;
-    state->state.Process = FlangerProcess;
+    GET_DERIVED_TYPE(ALeffectState, state)->Destroy = FlangerDestroy;
+    GET_DERIVED_TYPE(ALeffectState, state)->DeviceUpdate = FlangerDeviceUpdate;
+    GET_DERIVED_TYPE(ALeffectState, state)->Update = FlangerUpdate;
+    GET_DERIVED_TYPE(ALeffectState, state)->Process = FlangerProcess;
 
     state->BufferLength = 0;
     state->SampleBufferLeft = NULL;
     state->SampleBufferRight = NULL;
     state->offset = 0;
 
-    return &state->state;
+    return GET_DERIVED_TYPE(ALeffectState, state);
 }
 
 void flanger_SetParami(ALeffect *effect, ALCcontext *context, ALenum param, ALint val)
diff --git a/Alc/alcModulator.c b/Alc/alcModulator.c
index f1f8dadd..d33811ba 100644
--- a/Alc/alcModulator.c
+++ b/Alc/alcModulator.c
@@ -31,8 +31,7 @@
 
 
 typedef struct ALmodulatorState {
-    // Must be first in all effects!
-    ALeffectState state;
+    DERIVE_FROM_TYPE(ALeffectState);
 
     enum {
         SINUSOID,
@@ -116,7 +115,7 @@ DECL_TEMPLATE(Square)
 
 static ALvoid ModulatorDestroy(ALeffectState *effect)
 {
-    ALmodulatorState *state = (ALmodulatorState*)effect;
+    ALmodulatorState *state = GET_PARENT_TYPE(ALmodulatorState, ALeffectState, effect);
     free(state);
 }
 
@@ -129,7 +128,7 @@ static ALboolean ModulatorDeviceUpdate(ALeffectState *effect, ALCdevice *Device)
 
 static ALvoid ModulatorUpdate(ALeffectState *effect, ALCdevice *Device, const ALeffectslot *Slot)
 {
-    ALmodulatorState *state = (ALmodulatorState*)effect;
+    ALmodulatorState *state = GET_PARENT_TYPE(ALmodulatorState, ALeffectState, effect);
     ALfloat gain, cw, a = 0.0f;
     ALuint index;
 
@@ -162,7 +161,7 @@ static ALvoid ModulatorUpdate(ALeffectState *effect, ALCdevice *Device, const AL
 
 static ALvoid ModulatorProcess(ALeffectState *effect, ALuint SamplesToDo, const ALfloat *RESTRICT SamplesIn, ALfloat (*RESTRICT SamplesOut)[BUFFERSIZE])
 {
-    ALmodulatorState *state = (ALmodulatorState*)effect;
+    ALmodulatorState *state = GET_PARENT_TYPE(ALmodulatorState, ALeffectState, effect);
 
     switch(state->Waveform)
     {
@@ -188,10 +187,10 @@ ALeffectState *ModulatorCreate(void)
     if(!state)
         return NULL;
 
-    state->state.Destroy = ModulatorDestroy;
-    state->state.DeviceUpdate = ModulatorDeviceUpdate;
-    state->state.Update = ModulatorUpdate;
-    state->state.Process = ModulatorProcess;
+    GET_DERIVED_TYPE(ALeffectState, state)->Destroy = ModulatorDestroy;
+    GET_DERIVED_TYPE(ALeffectState, state)->DeviceUpdate = ModulatorDeviceUpdate;
+    GET_DERIVED_TYPE(ALeffectState, state)->Update = ModulatorUpdate;
+    GET_DERIVED_TYPE(ALeffectState, state)->Process = ModulatorProcess;
 
     state->index = 0;
     state->step = 1;
@@ -199,7 +198,7 @@ ALeffectState *ModulatorCreate(void)
     state->iirFilter.coeff = 0.0f;
     state->iirFilter.history[0] = 0.0f;
 
-    return &state->state;
+    return GET_DERIVED_TYPE(ALeffectState, state);
 }
 
 void mod_SetParamf(ALeffect *effect, ALCcontext *context, ALenum param, ALfloat val)
diff --git a/Alc/alcReverb.c b/Alc/alcReverb.c
index ab52ae77..ac9af905 100644
--- a/Alc/alcReverb.c
+++ b/Alc/alcReverb.c
@@ -40,8 +40,7 @@ typedef struct DelayLine
 } DelayLine;
 
 typedef struct ALverbState {
-    // Must be first in all effects!
-    ALeffectState state;
+    DERIVE_FROM_TYPE(ALeffectState);
 
     // All delay lines are allocated as a single buffer to reduce memory
     // fragmentation and management code.
@@ -557,7 +556,7 @@ static __inline ALvoid EAXVerbPass(ALverbState *State, ALfloat in, ALfloat *REST
 // buffer.
 static ALvoid VerbProcess(ALeffectState *effect, ALuint SamplesToDo, const ALfloat *RESTRICT SamplesIn, ALfloat (*RESTRICT SamplesOut)[BUFFERSIZE])
 {
-    ALverbState *State = (ALverbState*)effect;
+    ALverbState *State = GET_PARENT_TYPE(ALverbState, ALeffectState, effect);
     ALfloat (*RESTRICT out)[4] = State->ReverbSamples;
     ALuint index, c;
 
@@ -580,7 +579,7 @@ static ALvoid VerbProcess(ALeffectState *effect, ALuint SamplesToDo, const ALflo
 // buffer.
 static ALvoid EAXVerbProcess(ALeffectState *effect, ALuint SamplesToDo, const ALfloat *RESTRICT SamplesIn, ALfloat (*RESTRICT SamplesOut)[BUFFERSIZE])
 {
-    ALverbState *State = (ALverbState*)effect;
+    ALverbState *State = GET_PARENT_TYPE(ALverbState, ALeffectState, effect);
     ALfloat (*RESTRICT early)[4] = State->EarlySamples;
     ALfloat (*RESTRICT late)[4] = State->ReverbSamples;
     ALuint index, c;
@@ -727,7 +726,7 @@ static ALboolean AllocLines(ALuint frequency, ALverbState *State)
 // format) have been changed.
 static ALboolean ReverbDeviceUpdate(ALeffectState *effect, ALCdevice *Device)
 {
-    ALverbState *State = (ALverbState*)effect;
+    ALverbState *State = GET_PARENT_TYPE(ALverbState, ALeffectState, effect);
     ALuint frequency = Device->Frequency, index;
 
     // Allocate the delay lines.
@@ -1079,19 +1078,19 @@ static ALvoid Update3DPanning(const ALCdevice *Device, const ALfloat *Reflection
 // effect is loaded into a slot.
 static ALvoid ReverbUpdate(ALeffectState *effect, ALCdevice *Device, const ALeffectslot *Slot)
 {
-    ALverbState *State = (ALverbState*)effect;
+    ALverbState *State = GET_PARENT_TYPE(ALverbState, ALeffectState, effect);
     ALuint frequency = Device->Frequency;
     ALboolean isEAX = AL_FALSE;
     ALfloat cw, x, y, hfRatio;
 
     if(Slot->effect.type == AL_EFFECT_EAXREVERB && !EmulateEAXReverb)
     {
-        State->state.Process = EAXVerbProcess;
+        GET_DERIVED_TYPE(ALeffectState, State)->Process = EAXVerbProcess;
         isEAX = AL_TRUE;
     }
     else if(Slot->effect.type == AL_EFFECT_REVERB || EmulateEAXReverb)
     {
-        State->state.Process = VerbProcess;
+        GET_DERIVED_TYPE(ALeffectState, State)->Process = VerbProcess;
         isEAX = AL_FALSE;
     }
 
@@ -1174,7 +1173,7 @@ static ALvoid ReverbUpdate(ALeffectState *effect, ALCdevice *Device, const ALeff
 // slot has a different (or no) effect loaded over the reverb effect.
 static ALvoid ReverbDestroy(ALeffectState *effect)
 {
-    ALverbState *State = (ALverbState*)effect;
+    ALverbState *State = GET_PARENT_TYPE(ALverbState, ALeffectState, effect);
     if(State)
     {
         free(State->SampleBuffer);
@@ -1194,10 +1193,10 @@ ALeffectState *ReverbCreate(void)
     if(!State)
         return NULL;
 
-    State->state.Destroy = ReverbDestroy;
-    State->state.DeviceUpdate = ReverbDeviceUpdate;
-    State->state.Update = ReverbUpdate;
-    State->state.Process = VerbProcess;
+    GET_DERIVED_TYPE(ALeffectState, State)->Destroy = ReverbDestroy;
+    GET_DERIVED_TYPE(ALeffectState, State)->DeviceUpdate = ReverbDeviceUpdate;
+    GET_DERIVED_TYPE(ALeffectState, State)->Update = ReverbUpdate;
+    GET_DERIVED_TYPE(ALeffectState, State)->Process = VerbProcess;
 
     State->TotalSamples = 0;
     State->SampleBuffer = NULL;
@@ -1279,7 +1278,7 @@ ALeffectState *ReverbCreate(void)
 
     State->Gain = State->Late.PanGain;
 
-    return &State->state;
+    return GET_DERIVED_TYPE(ALeffectState, State);
 }
 
 void eaxreverb_SetParami(ALeffect *effect, ALCcontext *context, ALenum param, ALint val)
diff --git a/OpenAL32/Include/alMain.h b/OpenAL32/Include/alMain.h
index d234ae13..a1a90b2f 100644
--- a/OpenAL32/Include/alMain.h
+++ b/OpenAL32/Include/alMain.h
@@ -62,6 +62,10 @@ static const union {
 
 #define COUNTOF(x) (sizeof((x))/sizeof((x)[0]))
 
+#define DERIVE_FROM_TYPE(t)         t t##_parent
+#define GET_DERIVED_TYPE(t, o)      (&(o)->t##_parent)
+#define GET_PARENT_TYPE(t1, t2, o)  ((t1*)((char*)(o) - offsetof(t1, t2##_parent)))
+
 #ifdef _WIN32
 
 #define WIN32_LEAN_AND_MEAN