283 lines
8.4 KiB
C
Executable File
283 lines
8.4 KiB
C
Executable File
/* libFLAC - Free Lossless Audio Codec library
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* Copyright (C) 2006-2009 Josh Coalson
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* Copyright (C) 2011-2016 Xiph.Org Foundation
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* - Neither the name of the Xiph.org Foundation nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <math.h>
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#include "share/compat.h"
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#include "FLAC/assert.h"
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#include "FLAC/format.h"
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#include "private/window.h"
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#ifndef FLAC__INTEGER_ONLY_LIBRARY
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void FLAC__window_bartlett(FLAC__real *window, const FLAC__int32 L)
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{
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const FLAC__int32 N = L - 1;
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FLAC__int32 n;
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if (L & 1) {
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for (n = 0; n <= N/2; n++)
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window[n] = 2.0f * n / (float)N;
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for (; n <= N; n++)
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window[n] = 2.0f - 2.0f * n / (float)N;
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}
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else {
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for (n = 0; n <= L/2-1; n++)
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window[n] = 2.0f * n / (float)N;
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for (; n <= N; n++)
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window[n] = 2.0f - 2.0f * n / (float)N;
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}
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}
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void FLAC__window_bartlett_hann(FLAC__real *window, const FLAC__int32 L)
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{
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const FLAC__int32 N = L - 1;
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FLAC__int32 n;
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for (n = 0; n < L; n++)
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window[n] = (FLAC__real)(0.62f - 0.48f * fabs((float)n/(float)N-0.5f) - 0.38f * cos(2.0f * M_PI * ((float)n/(float)N)));
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}
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void FLAC__window_blackman(FLAC__real *window, const FLAC__int32 L)
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{
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const FLAC__int32 N = L - 1;
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FLAC__int32 n;
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for (n = 0; n < L; n++)
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window[n] = (FLAC__real)(0.42f - 0.5f * cos(2.0f * M_PI * n / N) + 0.08f * cos(4.0f * M_PI * n / N));
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}
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/* 4-term -92dB side-lobe */
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void FLAC__window_blackman_harris_4term_92db_sidelobe(FLAC__real *window, const FLAC__int32 L)
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{
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const FLAC__int32 N = L - 1;
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FLAC__int32 n;
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for (n = 0; n <= N; n++)
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window[n] = (FLAC__real)(0.35875f - 0.48829f * cos(2.0f * M_PI * n / N) + 0.14128f * cos(4.0f * M_PI * n / N) - 0.01168f * cos(6.0f * M_PI * n / N));
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}
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void FLAC__window_connes(FLAC__real *window, const FLAC__int32 L)
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{
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const FLAC__int32 N = L - 1;
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const double N2 = (double)N / 2.;
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FLAC__int32 n;
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for (n = 0; n <= N; n++) {
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double k = ((double)n - N2) / N2;
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k = 1.0f - k * k;
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window[n] = (FLAC__real)(k * k);
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}
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}
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void FLAC__window_flattop(FLAC__real *window, const FLAC__int32 L)
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{
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const FLAC__int32 N = L - 1;
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FLAC__int32 n;
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for (n = 0; n < L; n++)
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window[n] = (FLAC__real)(0.21557895f - 0.41663158f * cos(2.0f * M_PI * n / N) + 0.277263158f * cos(4.0f * M_PI * n / N) - 0.083578947f * cos(6.0f * M_PI * n / N) + 0.006947368f * cos(8.0f * M_PI * n / N));
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}
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void FLAC__window_gauss(FLAC__real *window, const FLAC__int32 L, const FLAC__real stddev)
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{
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const FLAC__int32 N = L - 1;
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const double N2 = (double)N / 2.;
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FLAC__int32 n;
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for (n = 0; n <= N; n++) {
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const double k = ((double)n - N2) / (stddev * N2);
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window[n] = (FLAC__real)exp(-0.5f * k * k);
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}
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}
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void FLAC__window_hamming(FLAC__real *window, const FLAC__int32 L)
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{
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const FLAC__int32 N = L - 1;
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FLAC__int32 n;
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for (n = 0; n < L; n++)
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window[n] = (FLAC__real)(0.54f - 0.46f * cos(2.0f * M_PI * n / N));
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}
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void FLAC__window_hann(FLAC__real *window, const FLAC__int32 L)
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{
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const FLAC__int32 N = L - 1;
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FLAC__int32 n;
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for (n = 0; n < L; n++)
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window[n] = (FLAC__real)(0.5f - 0.5f * cos(2.0f * M_PI * n / N));
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}
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void FLAC__window_kaiser_bessel(FLAC__real *window, const FLAC__int32 L)
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{
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const FLAC__int32 N = L - 1;
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FLAC__int32 n;
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for (n = 0; n < L; n++)
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window[n] = (FLAC__real)(0.402f - 0.498f * cos(2.0f * M_PI * n / N) + 0.098f * cos(4.0f * M_PI * n / N) - 0.001f * cos(6.0f * M_PI * n / N));
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}
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void FLAC__window_nuttall(FLAC__real *window, const FLAC__int32 L)
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{
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const FLAC__int32 N = L - 1;
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FLAC__int32 n;
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for (n = 0; n < L; n++)
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window[n] = (FLAC__real)(0.3635819f - 0.4891775f*cos(2.0f*M_PI*n/N) + 0.1365995f*cos(4.0f*M_PI*n/N) - 0.0106411f*cos(6.0f*M_PI*n/N));
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}
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void FLAC__window_rectangle(FLAC__real *window, const FLAC__int32 L)
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{
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FLAC__int32 n;
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for (n = 0; n < L; n++)
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window[n] = 1.0f;
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}
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void FLAC__window_triangle(FLAC__real *window, const FLAC__int32 L)
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{
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FLAC__int32 n;
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if (L & 1) {
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for (n = 1; n <= (L+1)/2; n++)
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window[n-1] = 2.0f * n / ((float)L + 1.0f);
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for (; n <= L; n++)
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window[n-1] = (float)(2 * (L - n + 1)) / ((float)L + 1.0f);
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}
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else {
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for (n = 1; n <= L/2; n++)
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window[n-1] = 2.0f * n / ((float)L + 1.0f);
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for (; n <= L; n++)
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window[n-1] = (float)(2 * (L - n + 1)) / ((float)L + 1.0f);
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}
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}
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void FLAC__window_tukey(FLAC__real *window, const FLAC__int32 L, const FLAC__real p)
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{
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if (p <= 0.0)
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FLAC__window_rectangle(window, L);
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else if (p >= 1.0)
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FLAC__window_hann(window, L);
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else {
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const FLAC__int32 Np = (FLAC__int32)(p / 2.0f * L) - 1;
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FLAC__int32 n;
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/* start with rectangle... */
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FLAC__window_rectangle(window, L);
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/* ...replace ends with hann */
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if (Np > 0) {
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for (n = 0; n <= Np; n++) {
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window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * n / Np));
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window[L-Np-1+n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * (n+Np) / Np));
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}
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}
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}
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}
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void FLAC__window_partial_tukey(FLAC__real *window, const FLAC__int32 L, const FLAC__real p, const FLAC__real start, const FLAC__real end)
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{
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const FLAC__int32 start_n = (FLAC__int32)(start * L);
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const FLAC__int32 end_n = (FLAC__int32)(end * L);
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const FLAC__int32 N = end_n - start_n;
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FLAC__int32 Np, n, i;
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if (p <= 0.0f)
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FLAC__window_partial_tukey(window, L, 0.05f, start, end);
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else if (p >= 1.0f)
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FLAC__window_partial_tukey(window, L, 0.95f, start, end);
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else {
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Np = (FLAC__int32)(p / 2.0f * N);
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for (n = 0; n < start_n && n < L; n++)
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window[n] = 0.0f;
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for (i = 1; n < (start_n+Np) && n < L; n++, i++)
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window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Np));
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for (; n < (end_n-Np) && n < L; n++)
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window[n] = 1.0f;
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for (i = Np; n < end_n && n < L; n++, i--)
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window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Np));
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for (; n < L; n++)
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window[n] = 0.0f;
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}
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}
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void FLAC__window_punchout_tukey(FLAC__real *window, const FLAC__int32 L, const FLAC__real p, const FLAC__real start, const FLAC__real end)
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{
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const FLAC__int32 start_n = (FLAC__int32)(start * L);
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const FLAC__int32 end_n = (FLAC__int32)(end * L);
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FLAC__int32 Ns, Ne, n, i;
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if (p <= 0.0f)
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FLAC__window_punchout_tukey(window, L, 0.05f, start, end);
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else if (p >= 1.0f)
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FLAC__window_punchout_tukey(window, L, 0.95f, start, end);
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else {
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Ns = (FLAC__int32)(p / 2.0f * start_n);
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Ne = (FLAC__int32)(p / 2.0f * (L - end_n));
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for (n = 0, i = 1; n < Ns && n < L; n++, i++)
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window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Ns));
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for (; n < start_n-Ns && n < L; n++)
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window[n] = 1.0f;
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for (i = Ns; n < start_n && n < L; n++, i--)
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window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Ns));
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for (; n < end_n && n < L; n++)
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window[n] = 0.0f;
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for (i = 1; n < end_n+Ne && n < L; n++, i++)
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window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Ne));
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for (; n < L - (Ne) && n < L; n++)
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window[n] = 1.0f;
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for (i = Ne; n < L; n++, i--)
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window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Ne));
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}
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}
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void FLAC__window_welch(FLAC__real *window, const FLAC__int32 L)
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{
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const FLAC__int32 N = L - 1;
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const double N2 = (double)N / 2.;
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FLAC__int32 n;
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for (n = 0; n <= N; n++) {
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const double k = ((double)n - N2) / N2;
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window[n] = (FLAC__real)(1.0f - k * k);
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}
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}
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#endif /* !defined FLAC__INTEGER_ONLY_LIBRARY */
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