Move ambidefs.h to core

2 files changed, 150 insertions, 0 deletions

diff --git a/core/ambidefs.cpp b/core/ambidefs.cpp
new file mode 100644
index 00000000..ab36d50b
--- /dev/null
+++ b/core/ambidefs.cpp
@@ -0,0 +1,15 @@
+
+#include "config.h"
+
+#include "ambidefs.h"
+
+
+constexpr std::array<float,MaxAmbiChannels> AmbiScale::FromN3D;
+constexpr std::array<float,MaxAmbiChannels> AmbiScale::FromSN3D;
+constexpr std::array<float,MaxAmbiChannels> AmbiScale::FromFuMa;
+constexpr std::array<uint8_t,MaxAmbiChannels> AmbiIndex::FromFuMa;
+constexpr std::array<uint8_t,MaxAmbi2DChannels> AmbiIndex::FromFuMa2D;
+constexpr std::array<uint8_t,MaxAmbiChannels> AmbiIndex::FromACN;
+constexpr std::array<uint8_t,MaxAmbi2DChannels> AmbiIndex::From2D;
+constexpr std::array<uint8_t,MaxAmbiChannels> AmbiIndex::OrderFromChannel;
+constexpr std::array<uint8_t,MaxAmbi2DChannels> AmbiIndex::OrderFrom2DChannel;
diff --git a/core/ambidefs.h b/core/ambidefs.h
new file mode 100644
index 00000000..05e3f5c8
--- /dev/null
+++ b/core/ambidefs.h
@@ -0,0 +1,135 @@
+#ifndef CORE_AMBIDEFS_H
+#define CORE_AMBIDEFS_H
+
+#include <array>
+#include <stddef.h>
+#include <stdint.h>
+
+using uint = unsigned int;
+
+/* The maximum number of Ambisonics channels. 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, third-order has 16, and fourth-order has 25.
+ */
+constexpr uint8_t MaxAmbiOrder{3};
+constexpr inline size_t AmbiChannelsFromOrder(size_t order) noexcept
+{ return (order+1) * (order+1); }
+constexpr size_t MaxAmbiChannels{AmbiChannelsFromOrder(MaxAmbiOrder)};
+
+/* A bitmask of ambisonic channels for 0 to 4th order. 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).
+ */
+constexpr uint Ambi0OrderMask{0x00000001};
+constexpr uint Ambi1OrderMask{0x0000000f};
+constexpr uint Ambi2OrderMask{0x000001ff};
+constexpr uint Ambi3OrderMask{0x0000ffff};
+constexpr uint Ambi4OrderMask{0x01ffffff};
+
+/* 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 is ACN ordering, with bit 0 being ACN 0, etc.
+ */
+constexpr uint AmbiPeriphonicMask{0xfe7ce4};
+
+/* The maximum number of ambisonic channels for 2D (non-periphonic)
+ * representation. This is 2 per each order above zero-order, plus 1 for zero-
+ * order. Or simply, o*2 + 1.
+ */
+constexpr inline size_t Ambi2DChannelsFromOrder(size_t order) noexcept
+{ return order*2 + 1; }
+constexpr size_t MaxAmbi2DChannels{Ambi2DChannelsFromOrder(MaxAmbiOrder)};
+
+
+/* NOTE: These are scale factors as applied to Ambisonics content. Decoder
+ * coefficients should be divided by these values to get proper scalings.
+ */
+struct AmbiScale {
+    static constexpr std::array<float,MaxAmbiChannels> FromN3D{{
+        1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
+        1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f
+    }};
+    static constexpr std::array<float,MaxAmbiChannels> FromSN3D{{
+        1.000000000f, /* ACN  0, sqrt(1) */
+        1.732050808f, /* ACN  1, sqrt(3) */
+        1.732050808f, /* ACN  2, sqrt(3) */
+        1.732050808f, /* ACN  3, sqrt(3) */
+        2.236067978f, /* ACN  4, sqrt(5) */
+        2.236067978f, /* ACN  5, sqrt(5) */
+        2.236067978f, /* ACN  6, sqrt(5) */
+        2.236067978f, /* ACN  7, sqrt(5) */
+        2.236067978f, /* ACN  8, sqrt(5) */
+        2.645751311f, /* ACN  9, sqrt(7) */
+        2.645751311f, /* ACN 10, sqrt(7) */
+        2.645751311f, /* ACN 11, sqrt(7) */
+        2.645751311f, /* ACN 12, sqrt(7) */
+        2.645751311f, /* ACN 13, sqrt(7) */
+        2.645751311f, /* ACN 14, sqrt(7) */
+        2.645751311f, /* ACN 15, sqrt(7) */
+    }};
+    static constexpr std::array<float,MaxAmbiChannels> FromFuMa{{
+        1.414213562f, /* ACN  0 (W), sqrt(2) */
+        1.732050808f, /* ACN  1 (Y), sqrt(3) */
+        1.732050808f, /* ACN  2 (Z), sqrt(3) */
+        1.732050808f, /* ACN  3 (X), sqrt(3) */
+        1.936491673f, /* ACN  4 (V), sqrt(15)/2 */
+        1.936491673f, /* ACN  5 (T), sqrt(15)/2 */
+        2.236067978f, /* ACN  6 (R), sqrt(5) */
+        1.936491673f, /* ACN  7 (S), sqrt(15)/2 */
+        1.936491673f, /* ACN  8 (U), sqrt(15)/2 */
+        2.091650066f, /* ACN  9 (Q), sqrt(35/8) */
+        1.972026594f, /* ACN 10 (O), sqrt(35)/3 */
+        2.231093404f, /* ACN 11 (M), sqrt(224/45) */
+        2.645751311f, /* ACN 12 (K), sqrt(7) */
+        2.231093404f, /* ACN 13 (L), sqrt(224/45) */
+        1.972026594f, /* ACN 14 (N), sqrt(35)/3 */
+        2.091650066f, /* ACN 15 (P), sqrt(35/8) */
+    }};
+};
+
+struct AmbiIndex {
+    static constexpr std::array<uint8_t,MaxAmbiChannels> FromFuMa{{
+        0,  /* W */
+        3,  /* X */
+        1,  /* Y */
+        2,  /* Z */
+        6,  /* R */
+        7,  /* S */
+        5,  /* T */
+        8,  /* U */
+        4,  /* V */
+        12, /* K */
+        13, /* L */
+        11, /* M */
+        14, /* N */
+        10, /* O */
+        15, /* P */
+        9,  /* Q */
+    }};
+    static constexpr std::array<uint8_t,MaxAmbi2DChannels> FromFuMa2D{{
+        0,  /* W */
+        3,  /* X */
+        1,  /* Y */
+        8,  /* U */
+        4,  /* V */
+        15, /* P */
+        9,  /* Q */
+    }};
+
+    static constexpr std::array<uint8_t,MaxAmbiChannels> FromACN{{
+        0,  1,  2,  3,  4,  5,  6,  7,
+        8,  9, 10, 11, 12, 13, 14, 15
+    }};
+    static constexpr std::array<uint8_t,MaxAmbi2DChannels> From2D{{
+        0, 1,3, 4,8, 9,15
+    }};
+
+    static constexpr std::array<uint8_t,MaxAmbiChannels> OrderFromChannel{{
+        0, 1,1,1, 2,2,2,2,2, 3,3,3,3,3,3,3,
+    }};
+    static constexpr std::array<uint8_t,MaxAmbi2DChannels> OrderFrom2DChannel{{
+        0, 1,1, 2,2, 3,3,
+    }};
+};
+
+#endif /* CORE_AMBIDEFS_H */