1 files changed, 124 insertions, 0 deletions
diff --git a/alc/hrtf.h b/alc/hrtf.h
new file mode 100644
index 00000000..6c41cb82
--- /dev/null
+++ b/alc/hrtf.h
@@ -0,0 +1,124 @@
+#ifndef ALC_HRTF_H
+#define ALC_HRTF_H
+
+#include <array>
+#include <cstddef>
+#include <memory>
+#include <string>
+
+#include "AL/al.h"
+
+#include "almalloc.h"
+#include "ambidefs.h"
+#include "atomic.h"
+#include "vector.h"
+
+
+struct HrtfHandle;
+
+#define HRTF_HISTORY_BITS   (6)
+#define HRTF_HISTORY_LENGTH (1<<HRTF_HISTORY_BITS)
+#define HRTF_HISTORY_MASK   (HRTF_HISTORY_LENGTH-1)
+
+#define HRIR_BITS        (7)
+#define HRIR_LENGTH      (1<<HRIR_BITS)
+#define HRIR_MASK        (HRIR_LENGTH-1)
+
+
+struct HrtfEntry {
+    RefCount ref;
+
+    ALuint sampleRate;
+    ALsizei irSize;
+
+    struct Field {
+        ALfloat distance;
+        ALubyte evCount;
+    };
+    /* NOTE: Fields are stored *backwards*. field[0] is the farthest field, and
+     * field[fdCount-1] is the nearest.
+     */
+    ALsizei fdCount;
+    const Field *field;
+
+    struct Elevation {
+        ALushort azCount;
+        ALushort irOffset;
+    };
+    Elevation *elev;
+    const ALfloat (*coeffs)[2];
+    const ALubyte (*delays)[2];
+
+    void IncRef();
+    void DecRef();
+
+    DEF_PLACE_NEWDEL()
+};
+
+struct EnumeratedHrtf {
+    std::string name;
+
+    HrtfHandle *hrtf;
+};
+
+
+using float2 = std::array<float,2>;
+
+template<typename T>
+using HrirArray = std::array<std::array<T,2>,HRIR_LENGTH>;
+
+struct HrtfState {
+    alignas(16) std::array<ALfloat,HRTF_HISTORY_LENGTH> History;
+    alignas(16) HrirArray<ALfloat> Values;
+};
+
+struct HrtfFilter {
+    alignas(16) HrirArray<ALfloat> Coeffs;
+    ALsizei Delay[2];
+    ALfloat Gain;
+};
+
+struct DirectHrtfState {
+    /* HRTF filter state for dry buffer content */
+    ALsizei IrSize{0};
+    struct ChanData {
+        alignas(16) HrirArray<ALfloat> Values;
+        alignas(16) HrirArray<ALfloat> Coeffs;
+    };
+    al::FlexArray<ChanData> Chan;
+
+    DirectHrtfState(size_t numchans) : Chan{numchans} { }
+    DirectHrtfState(const DirectHrtfState&) = delete;
+    DirectHrtfState& operator=(const DirectHrtfState&) = delete;
+
+    static std::unique_ptr<DirectHrtfState> Create(size_t num_chans);
+    static constexpr size_t Sizeof(size_t numchans) noexcept
+    { return al::FlexArray<ChanData>::Sizeof(numchans, offsetof(DirectHrtfState, Chan)); }
+
+    DEF_PLACE_NEWDEL()
+};
+
+struct AngularPoint {
+    ALfloat Elev;
+    ALfloat Azim;
+};
+
+
+al::vector<EnumeratedHrtf> EnumerateHrtf(const char *devname);
+HrtfEntry *GetLoadedHrtf(HrtfHandle *handle);
+
+void GetHrtfCoeffs(const HrtfEntry *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat distance,
+    ALfloat spread, HrirArray<ALfloat> &coeffs, ALsizei (&delays)[2]);
+
+/**
+ * Produces HRTF filter coefficients for decoding B-Format, given a set of
+ * virtual speaker positions, a matching decoding matrix, and per-order high-
+ * frequency gains for the decoder. The calculated impulse responses are
+ * ordered and scaled according to the matrix input. Note the specified virtual
+ * positions should be in degrees, not radians!
+ */
+void BuildBFormatHrtf(const HrtfEntry *Hrtf, DirectHrtfState *state, const ALuint NumChannels,
+    const AngularPoint *AmbiPoints, const ALfloat (*RESTRICT AmbiMatrix)[MAX_AMBI_CHANNELS],
+    const size_t AmbiCount, const ALfloat *RESTRICT AmbiOrderHFGain);
+
+#endif /* ALC_HRTF_H */