mirror of
https://github.com/ZLMediaKit/ZLMediaKit.git
synced 2024-11-26 20:47:08 +08:00
302 lines
8.4 KiB
C++
302 lines
8.4 KiB
C++
/*
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** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding
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** Copyright (C) 2003-2005 M. Bakker, Nero AG, http://www.nero.com
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**
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** This program is free software; you can redistribute it and/or modify
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** it under the terms of the GNU General Public License as published by
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** the Free Software Foundation; either version 2 of the License, or
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** (at your option) any later version.
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**
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** This program is distributed in the hope that it will be useful,
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** but WITHOUT ANY WARRANTY; without even the implied warranty of
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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** GNU General Public License for more details.
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**
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** You should have received a copy of the GNU General Public License
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** along with this program; if not, write to the Free Software
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** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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**
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** Any non-GPL usage of this software or parts of this software is strictly
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** forbidden.
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**
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** The "appropriate copyright message" mentioned in section 2c of the GPLv2
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** must read: "Code from FAAD2 is copyright (c) Nero AG, www.nero.com"
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**
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** Commercial non-GPL licensing of this software is possible.
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** For more info contact Nero AG through Mpeg4AAClicense@nero.com.
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**
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** $Id: mdct.c,v 1.47 2007/11/01 12:33:31 menno Exp $
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**/
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/*
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* Fast (I)MDCT Implementation using (I)FFT ((Inverse) Fast Fourier Transform)
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* and consists of three steps: pre-(I)FFT complex multiplication, complex
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* (I)FFT, post-(I)FFT complex multiplication,
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*
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* As described in:
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* P. Duhamel, Y. Mahieux, and J.P. Petit, "A Fast Algorithm for the
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* Implementation of Filter Banks Based on 'Time Domain Aliasing
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* Cancellation’," IEEE Proc. on ICASSP‘91, 1991, pp. 2209-2212.
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*
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*
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* As of April 6th 2002 completely rewritten.
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* This (I)MDCT can now be used for any data size n, where n is divisible by 8.
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*
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*/
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#include "common.h"
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#include "structs.h"
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#include <stdlib.h>
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#ifdef _WIN32_WCE
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#define assert(x)
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#else
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#include <assert.h>
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#endif
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#include "cfft.h"
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#include "mdct.h"
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#include "mdct_tab.h"
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mdct_info *faad_mdct_init(uint16_t N)
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{
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mdct_info *mdct = (mdct_info*)faad_malloc(sizeof(mdct_info));
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assert(N % 8 == 0);
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mdct->N = N;
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/* NOTE: For "small framelengths" in FIXED_POINT the coefficients need to be
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* scaled by sqrt("(nearest power of 2) > N" / N) */
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/* RE(mdct->sincos[k]) = scale*(real_t)(cos(2.0*M_PI*(k+1./8.) / (real_t)N));
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* IM(mdct->sincos[k]) = scale*(real_t)(sin(2.0*M_PI*(k+1./8.) / (real_t)N)); */
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/* scale is 1 for fixed point, sqrt(N) for floating point */
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switch (N)
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{
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case 2048: mdct->sincos = (complex_t*)mdct_tab_2048; break;
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case 256: mdct->sincos = (complex_t*)mdct_tab_256; break;
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#ifdef LD_DEC
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case 1024: mdct->sincos = (complex_t*)mdct_tab_1024; break;
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#endif
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#ifdef ALLOW_SMALL_FRAMELENGTH
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case 1920: mdct->sincos = (complex_t*)mdct_tab_1920; break;
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case 240: mdct->sincos = (complex_t*)mdct_tab_240; break;
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#ifdef LD_DEC
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case 960: mdct->sincos = (complex_t*)mdct_tab_960; break;
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#endif
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#endif
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#ifdef SSR_DEC
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case 512: mdct->sincos = (complex_t*)mdct_tab_512; break;
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case 64: mdct->sincos = (complex_t*)mdct_tab_64; break;
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#endif
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}
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/* initialise fft */
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mdct->cfft = cffti(N/4);
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#ifdef PROFILE
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mdct->cycles = 0;
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mdct->fft_cycles = 0;
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#endif
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return mdct;
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}
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void faad_mdct_end(mdct_info *mdct)
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{
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if (mdct != NULL)
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{
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#ifdef PROFILE
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printf("MDCT[%.4d]: %I64d cycles\n", mdct->N, mdct->cycles);
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printf("CFFT[%.4d]: %I64d cycles\n", mdct->N/4, mdct->fft_cycles);
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#endif
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cfftu(mdct->cfft);
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faad_free(mdct);
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}
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}
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void faad_imdct(mdct_info *mdct, real_t *X_in, real_t *X_out)
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{
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uint16_t k;
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complex_t x;
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#ifdef ALLOW_SMALL_FRAMELENGTH
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#ifdef FIXED_POINT
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real_t scale, b_scale = 0;
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#endif
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#endif
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ALIGN complex_t Z1[512];
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complex_t *sincos = mdct->sincos;
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uint16_t N = mdct->N;
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uint16_t N2 = N >> 1;
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uint16_t N4 = N >> 2;
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uint16_t N8 = N >> 3;
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#ifdef PROFILE
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int64_t count1, count2 = faad_get_ts();
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#endif
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#ifdef ALLOW_SMALL_FRAMELENGTH
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#ifdef FIXED_POINT
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/* detect non-power of 2 */
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if (N & (N-1))
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{
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/* adjust scale for non-power of 2 MDCT */
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/* 2048/1920 */
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b_scale = 1;
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scale = COEF_CONST(1.0666666666666667);
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}
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#endif
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#endif
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/* pre-IFFT complex multiplication */
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for (k = 0; k < N4; k++)
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{
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ComplexMult(&IM(Z1[k]), &RE(Z1[k]),
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X_in[2*k], X_in[N2 - 1 - 2*k], RE(sincos[k]), IM(sincos[k]));
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}
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#ifdef PROFILE
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count1 = faad_get_ts();
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#endif
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/* complex IFFT, any non-scaling FFT can be used here */
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cfftb(mdct->cfft, Z1);
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#ifdef PROFILE
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count1 = faad_get_ts() - count1;
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#endif
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/* post-IFFT complex multiplication */
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for (k = 0; k < N4; k++)
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{
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RE(x) = RE(Z1[k]);
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IM(x) = IM(Z1[k]);
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ComplexMult(&IM(Z1[k]), &RE(Z1[k]),
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IM(x), RE(x), RE(sincos[k]), IM(sincos[k]));
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#ifdef ALLOW_SMALL_FRAMELENGTH
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#ifdef FIXED_POINT
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/* non-power of 2 MDCT scaling */
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if (b_scale)
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{
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RE(Z1[k]) = MUL_C(RE(Z1[k]), scale);
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IM(Z1[k]) = MUL_C(IM(Z1[k]), scale);
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}
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#endif
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#endif
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}
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/* reordering */
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for (k = 0; k < N8; k+=2)
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{
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X_out[ 2*k] = IM(Z1[N8 + k]);
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X_out[ 2 + 2*k] = IM(Z1[N8 + 1 + k]);
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X_out[ 1 + 2*k] = -RE(Z1[N8 - 1 - k]);
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X_out[ 3 + 2*k] = -RE(Z1[N8 - 2 - k]);
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X_out[N4 + 2*k] = RE(Z1[ k]);
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X_out[N4 + + 2 + 2*k] = RE(Z1[ 1 + k]);
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X_out[N4 + 1 + 2*k] = -IM(Z1[N4 - 1 - k]);
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X_out[N4 + 3 + 2*k] = -IM(Z1[N4 - 2 - k]);
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X_out[N2 + 2*k] = RE(Z1[N8 + k]);
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X_out[N2 + + 2 + 2*k] = RE(Z1[N8 + 1 + k]);
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X_out[N2 + 1 + 2*k] = -IM(Z1[N8 - 1 - k]);
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X_out[N2 + 3 + 2*k] = -IM(Z1[N8 - 2 - k]);
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X_out[N2 + N4 + 2*k] = -IM(Z1[ k]);
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X_out[N2 + N4 + 2 + 2*k] = -IM(Z1[ 1 + k]);
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X_out[N2 + N4 + 1 + 2*k] = RE(Z1[N4 - 1 - k]);
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X_out[N2 + N4 + 3 + 2*k] = RE(Z1[N4 - 2 - k]);
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}
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#ifdef PROFILE
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count2 = faad_get_ts() - count2;
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mdct->fft_cycles += count1;
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mdct->cycles += (count2 - count1);
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#endif
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}
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#ifdef LTP_DEC
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void faad_mdct(mdct_info *mdct, real_t *X_in, real_t *X_out)
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{
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uint16_t k;
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complex_t x;
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ALIGN complex_t Z1[512];
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complex_t *sincos = mdct->sincos;
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uint16_t N = mdct->N;
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uint16_t N2 = N >> 1;
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uint16_t N4 = N >> 2;
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uint16_t N8 = N >> 3;
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#ifndef FIXED_POINT
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real_t scale = REAL_CONST(N);
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#else
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real_t scale = REAL_CONST(4.0/N);
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#endif
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#ifdef ALLOW_SMALL_FRAMELENGTH
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#ifdef FIXED_POINT
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/* detect non-power of 2 */
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if (N & (N-1))
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{
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/* adjust scale for non-power of 2 MDCT */
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/* *= sqrt(2048/1920) */
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scale = MUL_C(scale, COEF_CONST(1.0327955589886444));
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}
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#endif
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#endif
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/* pre-FFT complex multiplication */
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for (k = 0; k < N8; k++)
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{
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uint16_t n = k << 1;
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RE(x) = X_in[N - N4 - 1 - n] + X_in[N - N4 + n];
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IM(x) = X_in[ N4 + n] - X_in[ N4 - 1 - n];
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ComplexMult(&RE(Z1[k]), &IM(Z1[k]),
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RE(x), IM(x), RE(sincos[k]), IM(sincos[k]));
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RE(Z1[k]) = MUL_R(RE(Z1[k]), scale);
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IM(Z1[k]) = MUL_R(IM(Z1[k]), scale);
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RE(x) = X_in[N2 - 1 - n] - X_in[ n];
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IM(x) = X_in[N2 + n] + X_in[N - 1 - n];
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ComplexMult(&RE(Z1[k + N8]), &IM(Z1[k + N8]),
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RE(x), IM(x), RE(sincos[k + N8]), IM(sincos[k + N8]));
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RE(Z1[k + N8]) = MUL_R(RE(Z1[k + N8]), scale);
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IM(Z1[k + N8]) = MUL_R(IM(Z1[k + N8]), scale);
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}
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/* complex FFT, any non-scaling FFT can be used here */
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cfftf(mdct->cfft, Z1);
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/* post-FFT complex multiplication */
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for (k = 0; k < N4; k++)
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{
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uint16_t n = k << 1;
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ComplexMult(&RE(x), &IM(x),
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RE(Z1[k]), IM(Z1[k]), RE(sincos[k]), IM(sincos[k]));
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X_out[ n] = -RE(x);
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X_out[N2 - 1 - n] = IM(x);
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X_out[N2 + n] = -IM(x);
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X_out[N - 1 - n] = RE(x);
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}
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}
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#endif
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