Add fourth-order methods to the NFC filter

Unused, but it finishes out the currently possible implementations.

1 files changed, 9 insertions, 0 deletions

diff --git a/Alc/filters/nfc.h b/Alc/filters/nfc.h
index 40aca36e..ca4f6f58 100644
--- a/Alc/filters/nfc.h
+++ b/Alc/filters/nfc.h
@@ -16,11 +16,17 @@ struct NfcFilter3 {
     float b1, b2, b3, a1, a2, a3;
     float z[3];
 };
+struct NfcFilter4 {
+    float base_gain, gain;
+    float b1, b2, b3, b4, a1, a2, a3, a4;
+    float z[4];
+};
 
 class NfcFilter {
     NfcFilter1 first;
     NfcFilter2 second;
     NfcFilter3 third;
+    NfcFilter4 fourth;
 
 public:
     /* NOTE:
@@ -44,6 +50,9 @@ public:
 
     /* Near-field control filter for third-order ambisonic channels (9-15). */
     void process3(float *RESTRICT dst, const float *RESTRICT src, const int count);
+
+    /* Near-field control filter for fourth-order ambisonic channels (16-24). */
+    void process4(float *RESTRICT dst, const float *RESTRICT src, const int count);
 };
 
 #endif /* FILTER_NFC_H */