1/* -----------------------------------------------------------------------------
2Software License for The Fraunhofer FDK AAC Codec Library for Android
3
4© Copyright  1995 - 2018 Fraunhofer-Gesellschaft zur Förderung der angewandten
5Forschung e.V. All rights reserved.
6
7 1.    INTRODUCTION
8The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software
9that implements the MPEG Advanced Audio Coding ("AAC") encoding and decoding
10scheme for digital audio. This FDK AAC Codec software is intended to be used on
11a wide variety of Android devices.
12
13AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient
14general perceptual audio codecs. AAC-ELD is considered the best-performing
15full-bandwidth communications codec by independent studies and is widely
16deployed. AAC has been standardized by ISO and IEC as part of the MPEG
17specifications.
18
19Patent licenses for necessary patent claims for the FDK AAC Codec (including
20those of Fraunhofer) may be obtained through Via Licensing
21(www.vialicensing.com) or through the respective patent owners individually for
22the purpose of encoding or decoding bit streams in products that are compliant
23with the ISO/IEC MPEG audio standards. Please note that most manufacturers of
24Android devices already license these patent claims through Via Licensing or
25directly from the patent owners, and therefore FDK AAC Codec software may
26already be covered under those patent licenses when it is used for those
27licensed purposes only.
28
29Commercially-licensed AAC software libraries, including floating-point versions
30with enhanced sound quality, are also available from Fraunhofer. Users are
31encouraged to check the Fraunhofer website for additional applications
32information and documentation.
33
342.    COPYRIGHT LICENSE
35
36Redistribution and use in source and binary forms, with or without modification,
37are permitted without payment of copyright license fees provided that you
38satisfy the following conditions:
39
40You must retain the complete text of this software license in redistributions of
41the FDK AAC Codec or your modifications thereto in source code form.
42
43You must retain the complete text of this software license in the documentation
44and/or other materials provided with redistributions of the FDK AAC Codec or
45your modifications thereto in binary form. You must make available free of
46charge copies of the complete source code of the FDK AAC Codec and your
47modifications thereto to recipients of copies in binary form.
48
49The name of Fraunhofer may not be used to endorse or promote products derived
50from this library without prior written permission.
51
52You may not charge copyright license fees for anyone to use, copy or distribute
53the FDK AAC Codec software or your modifications thereto.
54
55Your modified versions of the FDK AAC Codec must carry prominent notices stating
56that you changed the software and the date of any change. For modified versions
57of the FDK AAC Codec, the term "Fraunhofer FDK AAC Codec Library for Android"
58must be replaced by the term "Third-Party Modified Version of the Fraunhofer FDK
59AAC Codec Library for Android."
60
613.    NO PATENT LICENSE
62
63NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without
64limitation the patents of Fraunhofer, ARE GRANTED BY THIS SOFTWARE LICENSE.
65Fraunhofer provides no warranty of patent non-infringement with respect to this
66software.
67
68You may use this FDK AAC Codec software or modifications thereto only for
69purposes that are authorized by appropriate patent licenses.
70
714.    DISCLAIMER
72
73This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright
74holders and contributors "AS IS" and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES,
75including but not limited to the implied warranties of merchantability and
76fitness for a particular purpose. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
77CONTRIBUTORS BE LIABLE for any direct, indirect, incidental, special, exemplary,
78or consequential damages, including but not limited to procurement of substitute
79goods or services; loss of use, data, or profits, or business interruption,
80however caused and on any theory of liability, whether in contract, strict
81liability, or tort (including negligence), arising in any way out of the use of
82this software, even if advised of the possibility of such damage.
83
845.    CONTACT INFORMATION
85
86Fraunhofer Institute for Integrated Circuits IIS
87Attention: Audio and Multimedia Departments - FDK AAC LL
88Am Wolfsmantel 33
8991058 Erlangen, Germany
90
91www.iis.fraunhofer.de/amm
92amm-info@iis.fraunhofer.de
93----------------------------------------------------------------------------- */
94
95/******************* Library for basic calculation routines ********************
96
97   Author(s):   Josef Hoepfl, DSP Solutions
98
99   Description: Fix point FFT
100
101*******************************************************************************/
102
103#ifndef FFT_H
104#define FFT_H
105
106#include "common_fix.h"
107
108/**
109 * \brief Perform an inplace complex valued FFT of length 2^n
110 *
111 * \param length Length of the FFT to be calculated.
112 * \param pInput Input/Output data buffer. The input data must have at least 1
113 * bit scale headroom. The values are interleaved, real/imag pairs.
114 * \param scalefactor Pointer to an INT, which contains the current scale of the
115 * input data, which is updated according to the FFT scale.
116 */
117void fft(int length, FIXP_DBL *pInput, INT *scalefactor);
118
119/**
120 * \brief Perform an inplace complex valued IFFT of length 2^n
121 *
122 * \param length Length of the FFT to be calculated.
123 * \param pInput Input/Output data buffer. The input data must have at least 1
124 * bit scale headroom. The values are interleaved, real/imag pairs.
125 * \param scalefactor Pointer to an INT, which contains the current scale of the
126 * input data, which is updated according to the IFFT scale.
127 */
128void ifft(int length, FIXP_DBL *pInput, INT *scalefactor);
129
130/*
131 * Frequently used and fixed short length FFTs.
132 */
133
134#ifndef FUNCTION_fft_4
135/**
136 * \brief Perform an inplace complex valued FFT of length 4
137 *
138 * \param pInput Input/Output data buffer. The input data must have at least 1
139 * bit scale headroom. The values are interleaved, real/imag pairs.
140 */
141LNK_SECTION_CODE_L1
142static void FDK_FORCEINLINE fft_4(FIXP_DBL *x) {
143  FIXP_DBL a00, a10, a20, a30, tmp0, tmp1;
144
145  a00 = (x[0] + x[4]) >> 1; /* Re A + Re B */
146  a10 = (x[2] + x[6]) >> 1; /* Re C + Re D */
147  a20 = (x[1] + x[5]) >> 1; /* Im A + Im B */
148  a30 = (x[3] + x[7]) >> 1; /* Im C + Im D */
149
150  x[0] = a00 + a10; /* Re A' = Re A + Re B + Re C + Re D */
151  x[1] = a20 + a30; /* Im A' = Im A + Im B + Im C + Im D */
152
153  tmp0 = a00 - x[4]; /* Re A - Re B */
154  tmp1 = a20 - x[5]; /* Im A - Im B */
155
156  x[4] = a00 - a10; /* Re C' = Re A + Re B - Re C - Re D */
157  x[5] = a20 - a30; /* Im C' = Im A + Im B - Im C - Im D */
158
159  a10 = a10 - x[6]; /* Re C - Re D */
160  a30 = a30 - x[7]; /* Im C - Im D */
161
162  x[2] = tmp0 + a30; /* Re B' = Re A - Re B + Im C - Im D */
163  x[6] = tmp0 - a30; /* Re D' = Re A - Re B - Im C + Im D */
164  x[3] = tmp1 - a10; /* Im B' = Im A - Im B - Re C + Re D */
165  x[7] = tmp1 + a10; /* Im D' = Im A - Im B + Re C - Re D */
166}
167#endif /* FUNCTION_fft_4 */
168
169#ifndef FUNCTION_fft_8
170LNK_SECTION_CODE_L1
171static void FDK_FORCEINLINE fft_8(FIXP_DBL *x) {
172  FIXP_SPK w_PiFOURTH = {{FIXP_SGL(0x5A82), FIXP_SGL(0x5A82)}};
173
174  FIXP_DBL a00, a10, a20, a30;
175  FIXP_DBL y[16];
176
177  a00 = (x[0] + x[8]) >> 1;
178  a10 = x[4] + x[12];
179  a20 = (x[1] + x[9]) >> 1;
180  a30 = x[5] + x[13];
181
182  y[0] = a00 + (a10 >> 1);
183  y[4] = a00 - (a10 >> 1);
184  y[1] = a20 + (a30 >> 1);
185  y[5] = a20 - (a30 >> 1);
186
187  a00 = a00 - x[8];
188  a10 = (a10 >> 1) - x[12];
189  a20 = a20 - x[9];
190  a30 = (a30 >> 1) - x[13];
191
192  y[2] = a00 + a30;
193  y[6] = a00 - a30;
194  y[3] = a20 - a10;
195  y[7] = a20 + a10;
196
197  a00 = (x[2] + x[10]) >> 1;
198  a10 = x[6] + x[14];
199  a20 = (x[3] + x[11]) >> 1;
200  a30 = x[7] + x[15];
201
202  y[8] = a00 + (a10 >> 1);
203  y[12] = a00 - (a10 >> 1);
204  y[9] = a20 + (a30 >> 1);
205  y[13] = a20 - (a30 >> 1);
206
207  a00 = a00 - x[10];
208  a10 = (a10 >> 1) - x[14];
209  a20 = a20 - x[11];
210  a30 = (a30 >> 1) - x[15];
211
212  y[10] = a00 + a30;
213  y[14] = a00 - a30;
214  y[11] = a20 - a10;
215  y[15] = a20 + a10;
216
217  FIXP_DBL vr, vi, ur, ui;
218
219  ur = y[0] >> 1;
220  ui = y[1] >> 1;
221  vr = y[8];
222  vi = y[9];
223  x[0] = ur + (vr >> 1);
224  x[1] = ui + (vi >> 1);
225  x[8] = ur - (vr >> 1);
226  x[9] = ui - (vi >> 1);
227
228  ur = y[4] >> 1;
229  ui = y[5] >> 1;
230  vi = y[12];
231  vr = y[13];
232  x[4] = ur + (vr >> 1);
233  x[5] = ui - (vi >> 1);
234  x[12] = ur - (vr >> 1);
235  x[13] = ui + (vi >> 1);
236
237  ur = y[10];
238  ui = y[11];
239
240  cplxMultDiv2(&vi, &vr, ui, ur, w_PiFOURTH);
241
242  ur = y[2];
243  ui = y[3];
244  x[2] = (ur >> 1) + vr;
245  x[3] = (ui >> 1) + vi;
246  x[10] = (ur >> 1) - vr;
247  x[11] = (ui >> 1) - vi;
248
249  ur = y[14];
250  ui = y[15];
251
252  cplxMultDiv2(&vr, &vi, ui, ur, w_PiFOURTH);
253
254  ur = y[6];
255  ui = y[7];
256  x[6] = (ur >> 1) + vr;
257  x[7] = (ui >> 1) - vi;
258  x[14] = (ur >> 1) - vr;
259  x[15] = (ui >> 1) + vi;
260}
261#endif /* FUNCTION_fft_8 */
262
263#endif
264