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synced 2025-11-05 13:30:02 -05:00
a57f2f25b6
Use a wrap around delay ringbuffer. We can then avoid some modulo arithmetic and read more efficiently. Also handle the delay convolver case better by reversing the taps and reading the taps and delay buffer without extra overhead.
57 lines
1 KiB
C
57 lines
1 KiB
C
/* Hilbert function */
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/* SPDX-FileCopyrightText: Copyright © 2021 Wim Taymans */
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/* SPDX-License-Identifier: MIT */
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#ifndef HILBERT_H
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#define HILBERT_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <errno.h>
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#include <stddef.h>
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#include <math.h>
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static inline void blackman_window(float *taps, int n_taps)
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{
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int n;
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for (n = 0; n < n_taps; n++) {
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float w = 2.0f * (float)M_PI * n / (n_taps-1);
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taps[n] = 0.3635819f - 0.4891775f * cosf(w)
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+ 0.1365995f * cosf(2 * w) - 0.0106411f * cosf(3 * w);
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}
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}
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static inline int hilbert_generate(float *taps, int n_taps)
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{
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int i;
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if ((n_taps & 1) == 0)
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return -EINVAL;
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for (i = 0; i < n_taps; i++) {
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int k = -(n_taps / 2) + i;
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if (k & 1) {
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float pk = (float)M_PI * k;
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taps[i] *= (1.0f - cosf(pk)) / pk;
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} else {
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taps[i] = 0.0f;
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}
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}
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return 0;
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}
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static inline void reverse_taps(float *taps, int n_taps)
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{
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int i;
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for (i = 0; i < n_taps/2; i++)
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SPA_SWAP(taps[i], taps[n_taps-1-i]);
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}
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#ifdef __cplusplus
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} /* extern "C" */
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#endif
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#endif /* HILBERT_H */
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