Mix reverb samples right after generating them

Instead of generating both the early and late reverb samples first, then mixing
them both to output, this now generates and mixes the early reflections then
generates and mixes the late reverb. There's no reason to hold both at the same
time so this reduces the amount of temporary storage needed.

1 files changed, 36 insertions, 31 deletions

diff --git a/Alc/effects/reverb.c b/Alc/effects/reverb.c
index f30956e5..3e157cbc 100644
--- a/Alc/effects/reverb.c
+++ b/Alc/effects/reverb.c
@@ -318,8 +318,7 @@ typedef struct ALreverbState {
 
     /* Temporary storage used when processing. */
     alignas(16) ALfloat AFormatSamples[NUM_LINES][MAX_UPDATE_SAMPLES];
-    alignas(16) ALfloat ReverbSamples[NUM_LINES][MAX_UPDATE_SAMPLES];
-    alignas(16) ALfloat EarlySamples[NUM_LINES][MAX_UPDATE_SAMPLES];
+    alignas(16) ALfloat MixSamples[NUM_LINES][MAX_UPDATE_SAMPLES];
 } ALreverbState;
 
 static ALvoid ALreverbState_Destruct(ALreverbState *State);
@@ -1520,8 +1519,7 @@ DECL_TEMPLATE(Faded)
 static ALvoid ALreverbState_process(ALreverbState *State, ALsizei SamplesToDo, const ALfloat (*restrict SamplesIn)[BUFFERSIZE], ALfloat (*restrict SamplesOut)[BUFFERSIZE], ALsizei NumChannels)
 {
     ALfloat (*restrict afmt)[MAX_UPDATE_SAMPLES] = State->AFormatSamples;
-    ALfloat (*restrict early)[MAX_UPDATE_SAMPLES] = State->EarlySamples;
-    ALfloat (*restrict late)[MAX_UPDATE_SAMPLES] = State->ReverbSamples;
+    ALfloat (*restrict samples)[MAX_UPDATE_SAMPLES] = State->MixSamples;
     ALsizei fadeCount = State->FadeCount;
     ALfloat fade = (ALfloat)fadeCount / FADE_SAMPLES;
     ALsizei base, c;
@@ -1544,32 +1542,53 @@ static ALvoid ALreverbState_process(ALreverbState *State, ALsizei SamplesToDo, c
         /* Process the samples for reverb. */
         for(c = 0;c < NUM_LINES;c++)
         {
-            /* Band-pass the incoming samples. Use the early output lines for
-             * temp storage.
-             */
-            BiquadFilter_process(&State->Filter[c].Lp, early[0], afmt[c], todo);
-            BiquadFilter_process(&State->Filter[c].Hp, early[1], early[0], todo);
+            /* Band-pass the incoming samples. */
+            BiquadFilter_process(&State->Filter[c].Lp, samples[0], afmt[c], todo);
+            BiquadFilter_process(&State->Filter[c].Hp, samples[1], samples[0], todo);
 
             /* Feed the initial delay line. */
-            DelayLineIn(&State->Delay, State->Offset, c, early[1], todo);
+            DelayLineIn(&State->Delay, State->Offset, c, samples[1], todo);
         }
 
         if(UNLIKELY(fadeCount < FADE_SAMPLES))
         {
             /* Generate early reflections. */
-            EarlyReflection_Faded(State, todo, fade, early);
+            EarlyReflection_Faded(State, todo, fade, samples);
+            /* Mix the A-Format results to output, implicitly converting back
+             * to B-Format.
+             */
+            for(c = 0;c < NUM_LINES;c++)
+                MixSamples(samples[c], NumChannels, SamplesOut,
+                    State->Early.CurrentGain[c], State->Early.PanGain[c],
+                    SamplesToDo-base, base, todo
+                );
 
-            /* Generate late reverb. */
-            LateReverb_Faded(State, todo, fade, late);
+            /* Generate and mix late reverb. */
+            LateReverb_Faded(State, todo, fade, samples);
             fade = minf(1.0f, fade + todo*FadeStep);
+            for(c = 0;c < NUM_LINES;c++)
+                MixSamples(samples[c], NumChannels, SamplesOut,
+                    State->Late.CurrentGain[c], State->Late.PanGain[c],
+                    SamplesToDo-base, base, todo
+                );
         }
         else
         {
-            /* Generate early reflections. */
-            EarlyReflection_Unfaded(State, todo, fade, early);
+            /* Generate and mix early reflections. */
+            EarlyReflection_Unfaded(State, todo, fade, samples);
+            for(c = 0;c < NUM_LINES;c++)
+                MixSamples(samples[c], NumChannels, SamplesOut,
+                    State->Early.CurrentGain[c], State->Early.PanGain[c],
+                    SamplesToDo-base, base, todo
+                );
 
-            /* Generate late reverb. */
-            LateReverb_Unfaded(State, todo, fade, late);
+            /* Generate and mix late reverb. */
+            LateReverb_Unfaded(State, todo, fade, samples);
+            for(c = 0;c < NUM_LINES;c++)
+                MixSamples(samples[c], NumChannels, SamplesOut,
+                    State->Late.CurrentGain[c], State->Late.PanGain[c],
+                    SamplesToDo-base, base, todo
+                );
         }
 
         /* Step all delays forward. */
@@ -1591,20 +1610,6 @@ static ALvoid ALreverbState_process(ALreverbState *State, ALsizei SamplesToDo, c
             }
         }
 
-        /* Mix the A-Format results to output, implicitly converting back to
-         * B-Format.
-         */
-        for(c = 0;c < NUM_LINES;c++)
-            MixSamples(early[c], NumChannels, SamplesOut,
-                State->Early.CurrentGain[c], State->Early.PanGain[c],
-                SamplesToDo-base, base, todo
-            );
-        for(c = 0;c < NUM_LINES;c++)
-            MixSamples(late[c], NumChannels, SamplesOut,
-                State->Late.CurrentGain[c], State->Late.PanGain[c],
-                SamplesToDo-base, base, todo
-            );
-
         base += todo;
     }
     State->FadeCount = fadeCount;