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311 lines
10 KiB
C
311 lines
10 KiB
C
/* Copyright (c) 2007-2008 CSIRO
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Copyright (c) 2007-2008 Xiph.Org Foundation
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Written by Jean-Marc Valin */
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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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- 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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- 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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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 COPYRIGHT OWNER
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OR 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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/* This is a simple MDCT implementation that uses a N/4 complex FFT
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to do most of the work. It should be relatively straightforward to
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plug in pretty much and FFT here.
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This replaces the Vorbis FFT (and uses the exact same API), which
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was a bit too messy and that was ending up duplicating code
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(might as well use the same FFT everywhere).
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The algorithm is similar to (and inspired from) Fabrice Bellard's
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MDCT implementation in FFMPEG, but has differences in signs, ordering
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and scaling in many places.
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*/
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#ifndef SKIP_CONFIG_H
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#endif
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#include "mdct.h"
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#include "kiss_fft.h"
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#include "_kiss_fft_guts.h"
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#include <math.h>
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#include "os_support.h"
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#include "mathops.h"
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#include "stack_alloc.h"
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#ifdef CUSTOM_MODES
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int clt_mdct_init(mdct_lookup *l,int N, int maxshift)
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{
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int i;
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int N4;
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kiss_twiddle_scalar *trig;
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#if defined(FIXED_POINT)
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int N2=N>>1;
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#endif
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l->n = N;
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N4 = N>>2;
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l->maxshift = maxshift;
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for (i=0;i<=maxshift;i++)
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{
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if (i==0)
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l->kfft[i] = opus_fft_alloc(N>>2>>i, 0, 0);
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else
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l->kfft[i] = opus_fft_alloc_twiddles(N>>2>>i, 0, 0, l->kfft[0]);
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#ifndef ENABLE_TI_DSPLIB55
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if (l->kfft[i]==NULL)
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return 0;
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#endif
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}
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l->trig = trig = (kiss_twiddle_scalar*)opus_alloc((N4+1)*sizeof(kiss_twiddle_scalar));
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if (l->trig==NULL)
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return 0;
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/* We have enough points that sine isn't necessary */
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#if defined(FIXED_POINT)
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for (i=0;i<=N4;i++)
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trig[i] = TRIG_UPSCALE*celt_cos_norm(DIV32(ADD32(SHL32(EXTEND32(i),17),N2),N));
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#else
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for (i=0;i<=N4;i++)
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trig[i] = (kiss_twiddle_scalar)cos(2*PI*i/N);
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#endif
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return 1;
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}
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void clt_mdct_clear(mdct_lookup *l)
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{
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int i;
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for (i=0;i<=l->maxshift;i++)
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opus_fft_free(l->kfft[i]);
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opus_free((kiss_twiddle_scalar*)l->trig);
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}
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#endif /* CUSTOM_MODES */
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/* Forward MDCT trashes the input array */
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void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * OPUS_RESTRICT out,
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const opus_val16 *window, int overlap, int shift, int stride)
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{
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int i;
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int N, N2, N4;
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kiss_twiddle_scalar sine;
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VARDECL(kiss_fft_scalar, f);
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VARDECL(kiss_fft_scalar, f2);
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SAVE_STACK;
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N = l->n;
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N >>= shift;
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N2 = N>>1;
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N4 = N>>2;
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ALLOC(f, N2, kiss_fft_scalar);
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ALLOC(f2, N2, kiss_fft_scalar);
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/* sin(x) ~= x here */
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#ifdef FIXED_POINT
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sine = TRIG_UPSCALE*(QCONST16(0.7853981f, 15)+N2)/N;
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#else
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sine = (kiss_twiddle_scalar)2*PI*(.125f)/N;
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#endif
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/* Consider the input to be composed of four blocks: [a, b, c, d] */
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/* Window, shuffle, fold */
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{
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/* Temp pointers to make it really clear to the compiler what we're doing */
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const kiss_fft_scalar * OPUS_RESTRICT xp1 = in+(overlap>>1);
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const kiss_fft_scalar * OPUS_RESTRICT xp2 = in+N2-1+(overlap>>1);
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kiss_fft_scalar * OPUS_RESTRICT yp = f;
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const opus_val16 * OPUS_RESTRICT wp1 = window+(overlap>>1);
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const opus_val16 * OPUS_RESTRICT wp2 = window+(overlap>>1)-1;
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for(i=0;i<((overlap+3)>>2);i++)
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{
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/* Real part arranged as -d-cR, Imag part arranged as -b+aR*/
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*yp++ = MULT16_32_Q15(*wp2, xp1[N2]) + MULT16_32_Q15(*wp1,*xp2);
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*yp++ = MULT16_32_Q15(*wp1, *xp1) - MULT16_32_Q15(*wp2, xp2[-N2]);
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xp1+=2;
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xp2-=2;
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wp1+=2;
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wp2-=2;
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}
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wp1 = window;
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wp2 = window+overlap-1;
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for(;i<N4-((overlap+3)>>2);i++)
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{
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/* Real part arranged as a-bR, Imag part arranged as -c-dR */
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*yp++ = *xp2;
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*yp++ = *xp1;
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xp1+=2;
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xp2-=2;
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}
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for(;i<N4;i++)
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{
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/* Real part arranged as a-bR, Imag part arranged as -c-dR */
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*yp++ = -MULT16_32_Q15(*wp1, xp1[-N2]) + MULT16_32_Q15(*wp2, *xp2);
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*yp++ = MULT16_32_Q15(*wp2, *xp1) + MULT16_32_Q15(*wp1, xp2[N2]);
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xp1+=2;
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xp2-=2;
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wp1+=2;
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wp2-=2;
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}
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}
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/* Pre-rotation */
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{
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kiss_fft_scalar * OPUS_RESTRICT yp = f;
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const kiss_twiddle_scalar *t = &l->trig[0];
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for(i=0;i<N4;i++)
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{
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kiss_fft_scalar re, im, yr, yi;
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re = yp[0];
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im = yp[1];
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yr = -S_MUL(re,t[i<<shift]) - S_MUL(im,t[(N4-i)<<shift]);
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yi = -S_MUL(im,t[i<<shift]) + S_MUL(re,t[(N4-i)<<shift]);
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/* works because the cos is nearly one */
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*yp++ = yr + S_MUL(yi,sine);
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*yp++ = yi - S_MUL(yr,sine);
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}
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}
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/* N/4 complex FFT, down-scales by 4/N */
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opus_fft(l->kfft[shift], (kiss_fft_cpx *)f, (kiss_fft_cpx *)f2);
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/* Post-rotate */
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{
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/* Temp pointers to make it really clear to the compiler what we're doing */
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const kiss_fft_scalar * OPUS_RESTRICT fp = f2;
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kiss_fft_scalar * OPUS_RESTRICT yp1 = out;
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kiss_fft_scalar * OPUS_RESTRICT yp2 = out+stride*(N2-1);
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const kiss_twiddle_scalar *t = &l->trig[0];
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/* Temp pointers to make it really clear to the compiler what we're doing */
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for(i=0;i<N4;i++)
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{
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kiss_fft_scalar yr, yi;
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yr = S_MUL(fp[1],t[(N4-i)<<shift]) + S_MUL(fp[0],t[i<<shift]);
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yi = S_MUL(fp[0],t[(N4-i)<<shift]) - S_MUL(fp[1],t[i<<shift]);
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/* works because the cos is nearly one */
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*yp1 = yr - S_MUL(yi,sine);
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*yp2 = yi + S_MUL(yr,sine);;
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fp += 2;
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yp1 += 2*stride;
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yp2 -= 2*stride;
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}
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}
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RESTORE_STACK;
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}
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void clt_mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * OPUS_RESTRICT out,
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const opus_val16 * OPUS_RESTRICT window, int overlap, int shift, int stride)
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{
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int i;
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int N, N2, N4;
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kiss_twiddle_scalar sine;
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VARDECL(kiss_fft_scalar, f2);
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SAVE_STACK;
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N = l->n;
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N >>= shift;
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N2 = N>>1;
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N4 = N>>2;
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ALLOC(f2, N2, kiss_fft_scalar);
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/* sin(x) ~= x here */
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#ifdef FIXED_POINT
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sine = TRIG_UPSCALE*(QCONST16(0.7853981f, 15)+N2)/N;
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#else
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sine = (kiss_twiddle_scalar)2*PI*(.125f)/N;
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#endif
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/* Pre-rotate */
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{
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/* Temp pointers to make it really clear to the compiler what we're doing */
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const kiss_fft_scalar * OPUS_RESTRICT xp1 = in;
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const kiss_fft_scalar * OPUS_RESTRICT xp2 = in+stride*(N2-1);
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kiss_fft_scalar * OPUS_RESTRICT yp = f2;
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const kiss_twiddle_scalar *t = &l->trig[0];
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for(i=0;i<N4;i++)
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{
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kiss_fft_scalar yr, yi;
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yr = -S_MUL(*xp2, t[i<<shift]) + S_MUL(*xp1,t[(N4-i)<<shift]);
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yi = -S_MUL(*xp2, t[(N4-i)<<shift]) - S_MUL(*xp1,t[i<<shift]);
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/* works because the cos is nearly one */
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*yp++ = yr - S_MUL(yi,sine);
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*yp++ = yi + S_MUL(yr,sine);
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xp1+=2*stride;
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xp2-=2*stride;
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}
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}
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/* Inverse N/4 complex FFT. This one should *not* downscale even in fixed-point */
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opus_ifft(l->kfft[shift], (kiss_fft_cpx *)f2, (kiss_fft_cpx *)(out+(overlap>>1)));
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/* Post-rotate and de-shuffle from both ends of the buffer at once to make
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it in-place. */
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{
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kiss_fft_scalar * OPUS_RESTRICT yp0 = out+(overlap>>1);
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kiss_fft_scalar * OPUS_RESTRICT yp1 = out+(overlap>>1)+N2-2;
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const kiss_twiddle_scalar *t = &l->trig[0];
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/* Loop to (N4+1)>>1 to handle odd N4. When N4 is odd, the
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middle pair will be computed twice. */
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for(i=0;i<(N4+1)>>1;i++)
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{
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kiss_fft_scalar re, im, yr, yi;
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kiss_twiddle_scalar t0, t1;
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re = yp0[0];
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im = yp0[1];
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t0 = t[i<<shift];
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t1 = t[(N4-i)<<shift];
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/* We'd scale up by 2 here, but instead it's done when mixing the windows */
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yr = S_MUL(re,t0) - S_MUL(im,t1);
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yi = S_MUL(im,t0) + S_MUL(re,t1);
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re = yp1[0];
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im = yp1[1];
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/* works because the cos is nearly one */
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yp0[0] = -(yr - S_MUL(yi,sine));
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yp1[1] = yi + S_MUL(yr,sine);
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t0 = t[(N4-i-1)<<shift];
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t1 = t[(i+1)<<shift];
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/* We'd scale up by 2 here, but instead it's done when mixing the windows */
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yr = S_MUL(re,t0) - S_MUL(im,t1);
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yi = S_MUL(im,t0) + S_MUL(re,t1);
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/* works because the cos is nearly one */
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yp1[0] = -(yr - S_MUL(yi,sine));
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yp0[1] = yi + S_MUL(yr,sine);
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yp0 += 2;
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yp1 -= 2;
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}
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}
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/* Mirror on both sides for TDAC */
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{
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kiss_fft_scalar * OPUS_RESTRICT xp1 = out+overlap-1;
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kiss_fft_scalar * OPUS_RESTRICT yp1 = out;
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const opus_val16 * OPUS_RESTRICT wp1 = window;
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const opus_val16 * OPUS_RESTRICT wp2 = window+overlap-1;
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for(i = 0; i < overlap/2; i++)
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{
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kiss_fft_scalar x1, x2;
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x1 = *xp1;
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x2 = *yp1;
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*yp1++ = MULT16_32_Q15(*wp2, x2) - MULT16_32_Q15(*wp1, x1);
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*xp1-- = MULT16_32_Q15(*wp1, x2) + MULT16_32_Q15(*wp2, x1);
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wp1++;
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wp2--;
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}
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}
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RESTORE_STACK;
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}
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