1/* libFLAC - Free Lossless Audio Codec library
2 * Copyright (C) 2006,2007  Josh Coalson
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * - Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *
11 * - Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * - Neither the name of the Xiph.org Foundation nor the names of its
16 * contributors may be used to endorse or promote products derived from
17 * this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
23 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
24 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
26 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
27 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
28 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
29 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#if HAVE_CONFIG_H
33#  include <config.h>
34#endif
35
36#include <math.h>
37#include "FLAC/assert.h"
38#include "FLAC/format.h"
39#include "private/window.h"
40
41#ifndef FLAC__INTEGER_ONLY_LIBRARY
42
43#ifndef M_PI
44/* math.h in VC++ doesn't seem to have this (how Microsoft is that?) */
45#define M_PI 3.14159265358979323846
46#endif
47
48
49void FLAC__window_bartlett(FLAC__real *window, const FLAC__int32 L)
50{
51	const FLAC__int32 N = L - 1;
52	FLAC__int32 n;
53
54	if (L & 1) {
55		for (n = 0; n <= N/2; n++)
56			window[n] = 2.0f * n / (float)N;
57		for (; n <= N; n++)
58			window[n] = 2.0f - 2.0f * n / (float)N;
59	}
60	else {
61		for (n = 0; n <= L/2-1; n++)
62			window[n] = 2.0f * n / (float)N;
63		for (; n <= N; n++)
64			window[n] = 2.0f - 2.0f * (N-n) / (float)N;
65	}
66}
67
68void FLAC__window_bartlett_hann(FLAC__real *window, const FLAC__int32 L)
69{
70	const FLAC__int32 N = L - 1;
71	FLAC__int32 n;
72
73	for (n = 0; n < L; n++)
74		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+0.5f)));
75}
76
77void FLAC__window_blackman(FLAC__real *window, const FLAC__int32 L)
78{
79	const FLAC__int32 N = L - 1;
80	FLAC__int32 n;
81
82	for (n = 0; n < L; n++)
83		window[n] = (FLAC__real)(0.42f - 0.5f * cos(2.0f * M_PI * n / N) + 0.08f * cos(4.0f * M_PI * n / N));
84}
85
86/* 4-term -92dB side-lobe */
87void FLAC__window_blackman_harris_4term_92db_sidelobe(FLAC__real *window, const FLAC__int32 L)
88{
89	const FLAC__int32 N = L - 1;
90	FLAC__int32 n;
91
92	for (n = 0; n <= N; n++)
93		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));
94}
95
96void FLAC__window_connes(FLAC__real *window, const FLAC__int32 L)
97{
98	const FLAC__int32 N = L - 1;
99	const double N2 = (double)N / 2.;
100	FLAC__int32 n;
101
102	for (n = 0; n <= N; n++) {
103		double k = ((double)n - N2) / N2;
104		k = 1.0f - k * k;
105		window[n] = (FLAC__real)(k * k);
106	}
107}
108
109void FLAC__window_flattop(FLAC__real *window, const FLAC__int32 L)
110{
111	const FLAC__int32 N = L - 1;
112	FLAC__int32 n;
113
114	for (n = 0; n < L; n++)
115		window[n] = (FLAC__real)(1.0f - 1.93f * cos(2.0f * M_PI * n / N) + 1.29f * cos(4.0f * M_PI * n / N) - 0.388f * cos(6.0f * M_PI * n / N) + 0.0322f * cos(8.0f * M_PI * n / N));
116}
117
118void FLAC__window_gauss(FLAC__real *window, const FLAC__int32 L, const FLAC__real stddev)
119{
120	const FLAC__int32 N = L - 1;
121	const double N2 = (double)N / 2.;
122	FLAC__int32 n;
123
124	for (n = 0; n <= N; n++) {
125		const double k = ((double)n - N2) / (stddev * N2);
126		window[n] = (FLAC__real)exp(-0.5f * k * k);
127	}
128}
129
130void FLAC__window_hamming(FLAC__real *window, const FLAC__int32 L)
131{
132	const FLAC__int32 N = L - 1;
133	FLAC__int32 n;
134
135	for (n = 0; n < L; n++)
136		window[n] = (FLAC__real)(0.54f - 0.46f * cos(2.0f * M_PI * n / N));
137}
138
139void FLAC__window_hann(FLAC__real *window, const FLAC__int32 L)
140{
141	const FLAC__int32 N = L - 1;
142	FLAC__int32 n;
143
144	for (n = 0; n < L; n++)
145		window[n] = (FLAC__real)(0.5f - 0.5f * cos(2.0f * M_PI * n / N));
146}
147
148void FLAC__window_kaiser_bessel(FLAC__real *window, const FLAC__int32 L)
149{
150	const FLAC__int32 N = L - 1;
151	FLAC__int32 n;
152
153	for (n = 0; n < L; n++)
154		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));
155}
156
157void FLAC__window_nuttall(FLAC__real *window, const FLAC__int32 L)
158{
159	const FLAC__int32 N = L - 1;
160	FLAC__int32 n;
161
162	for (n = 0; n < L; n++)
163		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));
164}
165
166void FLAC__window_rectangle(FLAC__real *window, const FLAC__int32 L)
167{
168	FLAC__int32 n;
169
170	for (n = 0; n < L; n++)
171		window[n] = 1.0f;
172}
173
174void FLAC__window_triangle(FLAC__real *window, const FLAC__int32 L)
175{
176	FLAC__int32 n;
177
178	if (L & 1) {
179		for (n = 1; n <= L+1/2; n++)
180			window[n-1] = 2.0f * n / ((float)L + 1.0f);
181		for (; n <= L; n++)
182			window[n-1] = - (float)(2 * (L - n + 1)) / ((float)L + 1.0f);
183	}
184	else {
185		for (n = 1; n <= L/2; n++)
186			window[n-1] = 2.0f * n / (float)L;
187		for (; n <= L; n++)
188			window[n-1] = ((float)(2 * (L - n)) + 1.0f) / (float)L;
189	}
190}
191
192void FLAC__window_tukey(FLAC__real *window, const FLAC__int32 L, const FLAC__real p)
193{
194	if (p <= 0.0)
195		FLAC__window_rectangle(window, L);
196	else if (p >= 1.0)
197		FLAC__window_hann(window, L);
198	else {
199		const FLAC__int32 Np = (FLAC__int32)(p / 2.0f * L) - 1;
200		FLAC__int32 n;
201		/* start with rectangle... */
202		FLAC__window_rectangle(window, L);
203		/* ...replace ends with hann */
204		if (Np > 0) {
205			for (n = 0; n <= Np; n++) {
206				window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * n / Np));
207				window[L-Np-1+n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * (n+Np) / Np));
208			}
209		}
210	}
211}
212
213void FLAC__window_welch(FLAC__real *window, const FLAC__int32 L)
214{
215	const FLAC__int32 N = L - 1;
216	const double N2 = (double)N / 2.;
217	FLAC__int32 n;
218
219	for (n = 0; n <= N; n++) {
220		const double k = ((double)n - N2) / N2;
221		window[n] = (FLAC__real)(1.0f - k * k);
222	}
223}
224
225#endif /* !defined FLAC__INTEGER_ONLY_LIBRARY */
226