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