add oversampler

oversampling/WDL/cmath/horner.h

@@ -0,0 +1,71 @@
+/*
+  horner.h
+  Copyright (C) 2011 and later Lubomir I. Ivanov (neolit123 [at] gmail)
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+/*
+  algorithm to evaluate integer order polynomials using horner's scheme.
+*/
+
+#ifndef _HORNER_H_
+#define _HORNER_H_
+
+#include "custom_math.h"
+#include "complex_number.h"
+
+/* settings */
+#ifndef _HORNER_INLINE
+  #define _HORNER_INLINE _CMATH_INLINE
+#else
+  #define _HORNER_INLINE
+#endif
+
+/* real */
+_HORNER_INLINE
+cmath_t horner_eval
+(const cmath_t *coeff, const cmath_t x, cmath_uint16_t order)
+{
+  register cmath_t y = coeff[0];
+  register cmath_uint16_t n = 1;
+  order += 1;
+  while(n < order)
+  {
+    y = y*x + coeff[n];
+    n++;
+  }
+  return y;
+}
+
+/* complex */
+_HORNER_INLINE
+cnum_s horner_eval_c
+(const cnum_s *coeff, const cnum_s x, cmath_uint16_t order)
+{
+  register cmath_uint16_t n = 1;
+  cnum_s y = coeff[0];
+  order += 1;
+  while(n < order)
+  {
+    y = cnum_add(cnum_mul(y, x), coeff[n]);
+    n++;
+  }
+  return y;
+}
+
+#endif /* _HORNER_H_ */