More directly map coefficients for ambisonic mixing buffers

Instead of looping over all the coefficients for each channel with multiplies,
when we know only one will have a non-0 factor for ambisonic mixing buffers,
just index the one with a non-0 factor.

2 files changed, 34 insertions, 7 deletions

diff --git a/OpenAL32/Include/alMain.h b/OpenAL32/Include/alMain.h
index 52296a15..12c4c610 100644
--- a/OpenAL32/Include/alMain.h
+++ b/OpenAL32/Include/alMain.h
@@ -509,8 +509,12 @@ struct ALCdevice_struct
     struct {
         /* Channel names for the dry buffer mix. */
         enum Channel ChannelName[MAX_OUTPUT_CHANNELS];
-        /* Ambisonic coefficients for mixing to the dry buffer. */
-        ChannelConfig AmbiCoeffs[MAX_OUTPUT_CHANNELS];
+        union {
+            /* Ambisonic coefficients for mixing to the dry buffer. */
+            ChannelConfig Coeffs[MAX_OUTPUT_CHANNELS];
+            /* Coefficient channel mapping for mixing to the dry buffer. */
+            BFChannelConfig Map[MAX_OUTPUT_CHANNELS];
+        } Ambi;
         /* Number of coefficients in each ChannelConfig to mix together (4 for
          * first-order, 9 for second-order, etc).
          */
@@ -523,8 +527,12 @@ struct ALCdevice_struct
 
     /* First-order ambisonics output, to be upsampled to the dry buffer if different. */
     struct {
-        /* Ambisonic coefficients for mixing. */
-        ChannelConfig AmbiCoeffs[MAX_OUTPUT_CHANNELS];
+        union {
+            ChannelConfig Coeffs[MAX_OUTPUT_CHANNELS];
+            BFChannelConfig Map[MAX_OUTPUT_CHANNELS];
+        } Ambi;
+        /* Will only be 4 or 0. */
+        ALuint CoeffCount;
 
         ALfloat (*Buffer)[BUFFERSIZE];
         ALuint NumChannels;
diff --git a/OpenAL32/Include/alu.h b/OpenAL32/Include/alu.h
index 8b11bdd4..c6b5aba0 100644
--- a/OpenAL32/Include/alu.h
+++ b/OpenAL32/Include/alu.h
@@ -330,7 +330,14 @@ void CalcAngleCoeffs(ALfloat azimuth, ALfloat elevation, ALfloat coeffs[MAX_AMBI
  *
  * Computes channel gains for ambient, omni-directional sounds.
  */
-void ComputeAmbientGains(const ChannelConfig *chancoeffs, ALuint numchans, ALfloat ingain, ALfloat gains[MAX_OUTPUT_CHANNELS]);
+#define ComputeAmbientGains(b, g, o) do {                                     \
+    if((b).CoeffCount > 0)                                                    \
+        ComputeAmbientGainsMC((b).Ambi.Coeffs, (b).NumChannels, g, o);        \
+    else                                                                      \
+        ComputeAmbientGainsBF((b).Ambi.Map, (b).NumChannels, g, o);           \
+} while (0)
+void ComputeAmbientGainsMC(const ChannelConfig *chancoeffs, ALuint numchans, ALfloat ingain, ALfloat gains[MAX_OUTPUT_CHANNELS]);
+void ComputeAmbientGainsBF(const BFChannelConfig *chanmap, ALuint numchans, ALfloat ingain, ALfloat gains[MAX_OUTPUT_CHANNELS]);
 
 /**
  * ComputePanningGains
@@ -338,7 +345,13 @@ void ComputeAmbientGains(const ChannelConfig *chancoeffs, ALuint numchans, ALflo
  * Computes panning gains using the given channel decoder coefficients and the
  * pre-calculated direction or angle coefficients.
  */
-void ComputePanningGains(const ChannelConfig *chancoeffs, ALuint numchans, ALuint numcoeffs, const ALfloat coeffs[MAX_AMBI_COEFFS], ALfloat ingain, ALfloat gains[MAX_OUTPUT_CHANNELS]);
+#define ComputePanningGains(b, c, g, o) do {                                  \
+    if((b).CoeffCount > 0)                                                    \
+        ComputePanningGainsMC((b).Ambi.Coeffs, (b).NumChannels, (b).CoeffCount, c, g, o);\
+    else                                                                      \
+        ComputePanningGainsBF((b).Ambi.Map, (b).NumChannels, c, g, o);        \
+} while (0)
+void ComputePanningGainsMC(const ChannelConfig *chancoeffs, ALuint numchans, ALuint numcoeffs, const ALfloat coeffs[MAX_AMBI_COEFFS], ALfloat ingain, ALfloat gains[MAX_OUTPUT_CHANNELS]);
 void ComputePanningGainsBF(const BFChannelConfig *chanmap, ALuint numchans, const ALfloat coeffs[MAX_AMBI_COEFFS], ALfloat ingain, ALfloat gains[MAX_OUTPUT_CHANNELS]);
 
 /**
@@ -348,7 +361,13 @@ void ComputePanningGainsBF(const BFChannelConfig *chanmap, ALuint numchans, cons
  * a 1x4 'slice' of a transform matrix for the input channel, used to scale and
  * orient the sound samples.
  */
-void ComputeFirstOrderGains(const ChannelConfig *chancoeffs, ALuint numchans, const ALfloat mtx[4], ALfloat ingain, ALfloat gains[MAX_OUTPUT_CHANNELS]);
+#define ComputeFirstOrderGains(b, m, g, o) do {                               \
+    if((b).CoeffCount > 0)                                                    \
+        ComputeFirstOrderGainsMC((b).Ambi.Coeffs, (b).NumChannels, m, g, o);  \
+    else                                                                      \
+        ComputeFirstOrderGainsBF((b).Ambi.Map, (b).NumChannels, m, g, o);     \
+} while (0)
+void ComputeFirstOrderGainsMC(const ChannelConfig *chancoeffs, ALuint numchans, const ALfloat mtx[4], ALfloat ingain, ALfloat gains[MAX_OUTPUT_CHANNELS]);
 void ComputeFirstOrderGainsBF(const BFChannelConfig *chanmap, ALuint numchans, const ALfloat mtx[4], ALfloat ingain, ALfloat gains[MAX_OUTPUT_CHANNELS]);