Improve the gain stepping difference check

Given the more stable stepping now in use, check that the total difference is
enough for perceptible transition, instead of the step itself.

3 files changed, 15 insertions, 12 deletions

diff --git a/Alc/mixer/mixer_c.c b/Alc/mixer/mixer_c.c
index 2dcd6c6b..14d7c669 100644
--- a/Alc/mixer/mixer_c.c
+++ b/Alc/mixer/mixer_c.c
@@ -108,21 +108,22 @@ void Mix_C(const ALfloat *data, ALsizei OutChans, ALfloat (*restrict OutBuffer)[
            ALfloat *CurrentGains, const ALfloat *TargetGains, ALsizei Counter, ALsizei OutPos,
            ALsizei BufferSize)
 {
-    ALfloat gain, delta, step;
+    const ALfloat delta = (Counter > 0) ? 1.0f/(ALfloat)Counter : 0.0f;
     ALsizei c;
 
     ASSUME(OutChans > 0);
     ASSUME(BufferSize > 0);
-    delta = (Counter > 0) ? 1.0f/(ALfloat)Counter : 0.0f;
 
     for(c = 0;c < OutChans;c++)
     {
         ALsizei pos = 0;
-        gain = CurrentGains[c];
-        step = (TargetGains[c] - gain) * delta;
-        if(fabsf(step) > FLT_EPSILON)
+        ALfloat gain = CurrentGains[c];
+        const ALfloat diff = TargetGains[c] - gain;
+
+        if(fabsf(diff) > FLT_EPSILON)
         {
             ALsizei minsize = mini(BufferSize, Counter);
+            const ALfloat step = diff * delta;
             ALfloat step_count = 0.0f;
             for(;pos < minsize;pos++)
             {
@@ -158,7 +159,7 @@ void MixRow_C(ALfloat *OutBuffer, const ALfloat *Gains, const ALfloat (*restrict
 
     for(c = 0;c < InChans;c++)
     {
-        ALfloat gain = Gains[c];
+        const ALfloat gain = Gains[c];
         if(!(fabsf(gain) > GAIN_SILENCE_THRESHOLD))
             continue;
 
diff --git a/Alc/mixer/mixer_neon.c b/Alc/mixer/mixer_neon.c
index ca274b07..9bf5521a 100644
--- a/Alc/mixer/mixer_neon.c
+++ b/Alc/mixer/mixer_neon.c
@@ -179,11 +179,12 @@ void Mix_Neon(const ALfloat *data, ALsizei OutChans, ALfloat (*restrict OutBuffe
     {
         ALsizei pos = 0;
         ALfloat gain = CurrentGains[c];
-        const ALfloat step = (TargetGains[c] - gain) * delta;
+        const ALfloat diff = TargetGains[c] - gain;
 
-        if(fabsf(step) > FLT_EPSILON)
+        if(fabsf(diff) > FLT_EPSILON)
         {
             ALsizei minsize = mini(BufferSize, Counter);
+            const ALfloat step = diff * delta;
             ALfloat step_count = 0.0f;
             /* Mix with applying gain steps in aligned multiples of 4. */
             if(LIKELY(minsize > 3))
@@ -260,7 +261,7 @@ void MixRow_Neon(ALfloat *OutBuffer, const ALfloat *Gains, const ALfloat (*restr
     for(c = 0;c < InChans;c++)
     {
         ALsizei pos = 0;
-        ALfloat gain = Gains[c];
+        const ALfloat gain = Gains[c];
         if(!(fabsf(gain) > GAIN_SILENCE_THRESHOLD))
             continue;
 
diff --git a/Alc/mixer/mixer_sse.c b/Alc/mixer/mixer_sse.c
index 78cf26f1..725a5ebc 100644
--- a/Alc/mixer/mixer_sse.c
+++ b/Alc/mixer/mixer_sse.c
@@ -149,11 +149,12 @@ void Mix_SSE(const ALfloat *data, ALsizei OutChans, ALfloat (*restrict OutBuffer
     {
         ALsizei pos = 0;
         ALfloat gain = CurrentGains[c];
-        const ALfloat step = (TargetGains[c] - gain) * delta;
+        const ALfloat diff = TargetGains[c] - gain;
 
-        if(fabsf(step) > FLT_EPSILON)
+        if(fabsf(diff) > FLT_EPSILON)
         {
             ALsizei minsize = mini(BufferSize, Counter);
+            const ALfloat step = diff * delta;
             ALfloat step_count = 0.0f;
             /* Mix with applying gain steps in aligned multiples of 4. */
             if(LIKELY(minsize > 3))
@@ -227,7 +228,7 @@ void MixRow_SSE(ALfloat *OutBuffer, const ALfloat *Gains, const ALfloat (*restri
     for(c = 0;c < InChans;c++)
     {
         ALsizei pos = 0;
-        ALfloat gain = Gains[c];
+        const ALfloat gain = Gains[c];
         if(!(fabsf(gain) > GAIN_SILENCE_THRESHOLD))
             continue;