Use an interpolated FIR filter for cubic resampling

Similar to how the bsinc filters work, but optimized for 4-point filtering. At
least the SSE version is notably faster than calculating the coefficients in
real time.

1 files changed, 13 insertions, 0 deletions

diff --git a/core/cubic_defs.h b/core/cubic_defs.h
new file mode 100644
index 00000000..33751c97
--- /dev/null
+++ b/core/cubic_defs.h
@@ -0,0 +1,13 @@
+#ifndef CORE_CUBIC_DEFS_H
+#define CORE_CUBIC_DEFS_H
+
+/* The number of distinct phase intervals within the cubic filter tables. */
+constexpr unsigned int CubicPhaseBits{5};
+constexpr unsigned int CubicPhaseCount{1 << CubicPhaseBits};
+
+struct CubicCoefficients {
+    float mCoeffs[4];
+    float mDeltas[4];
+};
+
+#endif /* CORE_CUBIC_DEFS_H */