Move the ALcomplex and FFT functions to a separate file

1 files changed, 62 insertions, 0 deletions

diff --git a/common/alcomplex.h b/common/alcomplex.h
new file mode 100644
index 00000000..cf4683fa
--- /dev/null
+++ b/common/alcomplex.h
@@ -0,0 +1,62 @@
+#ifndef ALCOMPLEX_H
+#define ALCOMPLEX_H
+
+#include "AL/al.h"
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct ALcomplex {
+    ALdouble Real;
+    ALdouble Imag;
+} ALcomplex;
+
+/** Addition of two complex numbers. */
+inline ALcomplex complex_add(ALcomplex a, ALcomplex b)
+{
+    ALcomplex result;
+
+    result.Real = a.Real + b.Real;
+    result.Imag = a.Imag + b.Imag;
+
+    return result;
+}
+
+/** Subtraction of two complex numbers. */
+inline ALcomplex complex_sub(ALcomplex a, ALcomplex b)
+{
+    ALcomplex result;
+
+    result.Real = a.Real - b.Real;
+    result.Imag = a.Imag - b.Imag;
+
+    return result;
+}
+
+/** Multiplication of two complex numbers. */
+inline ALcomplex complex_mult(ALcomplex a, ALcomplex b)
+{
+    ALcomplex result;
+
+    result.Real = a.Real*b.Real - a.Imag*b.Imag;
+    result.Imag = a.Imag*b.Real + a.Real*b.Imag;
+
+    return result;
+}
+
+/**
+ * Iterative implementation of 2-radix FFT (In-place algorithm). Sign = -1 is
+ * FFT and 1 is iFFT (inverse). Fills FFTBuffer[0...FFTSize-1] with the
+ * Discrete Fourier Transform (DFT) of the time domain data stored in
+ * FFTBuffer[0...FFTSize-1]. FFTBuffer is an array of complex numbers, FFTSize
+ * MUST BE power of two.
+ */
+void complex_fft(ALcomplex *FFTBuffer, ALsizei FFTSize, ALdouble Sign);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif /* ALCOMPLEX_H */