1 files changed, 47 insertions, 0 deletions
diff --git a/lib/sinc.c b/lib/sinc.c
new file mode 100644
index 0000000..779c8da
--- /dev/null
+++ b/lib/sinc.c
@@ -0,0 +1,47 @@
+// Sinc
+//
+// sinc - Normalized Sinc function
+//
+// y[t] = x[t] == 0 ? 1 : sin( pi * x[t] ) / ( pi * x[t] )
+//
+// X_n - 1
+// Y_n - 1
+// C_n - 0
+
+
+#include <math.h>
+#include "ts.h"
+
+
+
+ts_parameter_t const ts_sinc_p = { .n_inputs = 1, .n_outputs = 1, .n_constants = 0, .params_size = 0 };
+
+
+uint_t ts_sinc_offset( ts_constant_t const *c )
+{
+	( void )c;
+	return ( 0 );
+}
+
+int ts_sinc(
+	fp_t * const *y, uint_t y_n,
+	fp_t const * const *x, uint_t x_n,
+	uint_t n, ts_constant_t const *c
+)
+{
+	TS_PROLOGUE( ts_sinc_p );
+	(void)c;
+	for( uint_t i = 0; i < n; ++i )
+	{
+		fp_t xi = x[0][i];
+		if ( xi == 0 )
+			y[0][i] = 1;
+		else
+		{
+			fp_t pix = PI * xi;
+			y[0][i] = sin( pix ) / pix;
+		}
+	}
+	return 0;
+}
+