From c63d468d4cc738ead65ff7ebc9cf6afcad400ee1 Mon Sep 17 00:00:00 2001
From: Chris Robinson <chris.kcat@gmail.com>
Date: Wed, 1 Jun 2016 05:30:06 -0700
Subject: [PATCH] Use a macro to specify the ambisonic periphonic channel mask

---
 Alc/bformatdec.c          |  2 +-
 Alc/panning.c             |  4 ++--
 OpenAL32/Include/alMain.h | 11 ++++++++++-
 3 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/Alc/bformatdec.c b/Alc/bformatdec.c
index a871fb09..7da50692 100644
--- a/Alc/bformatdec.c
+++ b/Alc/bformatdec.c
@@ -310,7 +310,7 @@ void bformatdec_reset(BFormatDec *dec, const AmbDecConf *conf, ALuint chancount,
     ratio = 400.0f / (ALfloat)srate;
     for(i = 0;i < 4;i++)
         bandsplit_init(&dec->UpSampler.XOver[i], ratio);
-    if((conf->ChanMask & ~0x831b))
+    if((conf->ChanMask&AMBI_PERIPHONIC_MASK))
     {
         dec->UpSampler.MatrixHF = CubeMatrixHF;
         dec->UpSampler.MatrixLF = CubeMatrixLF;
diff --git a/Alc/panning.c b/Alc/panning.c
index 2116e739..6949c565 100644
--- a/Alc/panning.c
+++ b/Alc/panning.c
@@ -673,7 +673,7 @@ static void InitHQPanning(ALCdevice *device, const AmbDecConf *conf, const ALuin
     if(GetConfigValueBool(devname, "decoder", "distance-comp", 1))
         decflags |= BFDF_DistanceComp;
 
-    if((conf->ChanMask & ~0x831b))
+    if((conf->ChanMask&AMBI_PERIPHONIC_MASK))
     {
         count = (conf->ChanMask > 0x1ff) ? 16 :
                 (conf->ChanMask > 0xf) ? 9 : 4;
@@ -701,7 +701,7 @@ static void InitHQPanning(ALCdevice *device, const AmbDecConf *conf, const ALuin
     TRACE("Enabling %s-band %s-order%s ambisonic decoder\n",
         (conf->FreqBands == 1) ? "single" : "dual",
         (conf->ChanMask > 0xf) ? (conf->ChanMask > 0x1ff) ? "third" : "second" : "first",
-        (conf->ChanMask & ~0x831b) ? " periphonic" : ""
+        (conf->ChanMask&AMBI_PERIPHONIC_MASK) ? " periphonic" : ""
     );
     bformatdec_reset(device->AmbiDecoder, conf, count, device->Frequency,
                      speakermap, decflags);
diff --git a/OpenAL32/Include/alMain.h b/OpenAL32/Include/alMain.h
index d7b54310..18aa4df3 100644
--- a/OpenAL32/Include/alMain.h
+++ b/OpenAL32/Include/alMain.h
@@ -483,10 +483,19 @@ enum RenderMode {
 
 /* The maximum number of Ambisonics coefficients. For a given order (o), the
  * size needed will be (o+1)**2, thus zero-order has 1, first-order has 4,
- * second-order has 9, and third-order has 16. */
+ * second-order has 9, third-order has 16, and fourth-order has 25. */
 #define MAX_AMBI_ORDER  3
 #define MAX_AMBI_COEFFS ((MAX_AMBI_ORDER+1) * (MAX_AMBI_ORDER+1))
 
+/* A bitmask of ambisonic channels with height information. If none of these
+ * channels are used/needed, there's no height (e.g. with most surround sound
+ * speaker setups). This only specifies up to 4th order, which is the highest
+ * order a 32-bit mask value can specify (a 64-bit mask could handle up to 7th
+ * order). This is ACN ordering, with bit 0 being ACN 0, etc.
+ */
+#define AMBI_PERIPHONIC_MASK (0xfe7ce4)
+
+
 typedef ALfloat ChannelConfig[MAX_AMBI_COEFFS];
 typedef struct BFChannelConfig {
     ALfloat Scale;
-- 
2.11.4.GIT