window.hpp

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#pragma once
#include <math.hpp>
#include <simd/Vector.hpp>
#include <simd/functions.hpp>
 
 
namespace rack {
namespace dsp {
 

template <typename T>
inline T hann(T p) {
    return T(0.5) * (1 - simd::cos(2 * T(M_PI) * p));
}

inline void hannWindow(float* x, int len) {
    for (int i = 0; i < len; i++) {
        x[i] *= hann(float(i) / (len - 1));
    }
}

template <typename T>
inline T blackman(T alpha, T p) {
    return
      + (1 - alpha) / 2
      - T(1) / 2 * simd::cos(2 * T(M_PI) * p)
      + alpha / 2 * simd::cos(4 * T(M_PI) * p);
}
 
inline void blackmanWindow(float alpha, float* x, int len) {
    for (int i = 0; i < len; i++) {
        x[i] *= blackman(alpha, float(i) / (len - 1));
    }
}
 

template <typename T>
inline T blackmanNuttall(T p) {
    return
      + T(0.3635819)
      - T(0.4891775) * simd::cos(2 * T(M_PI) * p)
      + T(0.1365995) * simd::cos(4 * T(M_PI) * p)
      - T(0.0106411) * simd::cos(6 * T(M_PI) * p);
}
 
inline void blackmanNuttallWindow(float* x, int len) {
    for (int i = 0; i < len; i++) {
        x[i] *= blackmanNuttall(float(i) / (len - 1));
    }
}

template <typename T>
inline T blackmanHarris(T p) {
    return
      + T(0.35875)
      - T(0.48829) * simd::cos(2 * T(M_PI) * p)
      + T(0.14128) * simd::cos(4 * T(M_PI) * p)
      - T(0.01168) * simd::cos(6 * T(M_PI) * p);
}
 
inline void blackmanHarrisWindow(float* x, int len) {
    for (int i = 0; i < len; i++) {
        x[i] *= blackmanHarris(float(i) / (len - 1));
    }
}
 
 
} // namespace dsp
} // namespace rack