287 lines
9.1 KiB
C++
287 lines
9.1 KiB
C++
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/* 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 __MDCT_MIPSR1_H__
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#define __MDCT_MIPSR1_H__
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#ifndef SKIP_CONFIG_H
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#include "opus/opus_config.h"
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#endif
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#include "opus/celt/mdct.h"
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#include "opus/celt/kiss_fft.h"
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#include "opus/celt/_kiss_fft_guts.h"
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#include <math.h>
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#include "opus/celt/os_support.h"
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#include "opus/celt/mathops.h"
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#include "opus/celt/stack_alloc.h"
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/* Forward MDCT trashes the input array */
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#define OVERRIDE_clt_mdct_forward
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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, int arch)
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{
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int i;
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int N, N2, N4;
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VARDECL(kiss_fft_scalar, f);
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VARDECL(kiss_fft_cpx, f2);
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const kiss_fft_state *st = l->kfft[shift];
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const kiss_twiddle_scalar *trig;
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opus_val16 scale;
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#ifdef OPUS_FIXED_POINT
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/* Allows us to scale with MULT16_32_Q16(), which is faster than
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MULT16_32_Q15() on ARM. */
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int scale_shift = st->scale_shift-1;
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#endif
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(void)arch;
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SAVE_STACK;
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scale = st->scale;
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N = l->n;
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trig = l->trig;
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for (i=0;i<shift;i++)
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{
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N >>= 1;
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trig += N;
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}
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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, N4, kiss_fft_cpx);
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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++ = S_MUL_ADD(*wp2, xp1[N2],*wp1,*xp2);
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*yp++ = S_MUL_SUB(*wp1, *xp1,*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++ = S_MUL_SUB(*wp2, *xp2, *wp1, xp1[-N2]);
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*yp++ = S_MUL_ADD(*wp2, *xp1, *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 = &trig[0];
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for(i=0;i<N4;i++)
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{
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kiss_fft_cpx yc;
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kiss_twiddle_scalar t0, t1;
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kiss_fft_scalar re, im, yr, yi;
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t0 = t[i];
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t1 = t[N4+i];
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re = *yp++;
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im = *yp++;
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yr = S_MUL_SUB(re,t0,im,t1);
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yi = S_MUL_ADD(im,t0,re,t1);
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yc.r = yr;
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yc.i = yi;
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yc.r = PSHR32(MULT16_32_Q16(scale, yc.r), scale_shift);
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yc.i = PSHR32(MULT16_32_Q16(scale, yc.i), scale_shift);
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f2[st->bitrev[i]] = yc;
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}
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}
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/* N/4 complex FFT, does not downscale anymore */
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opus_fft_impl(st, 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_cpx * 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 = &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_SUB(fp->i,t[N4+i] , fp->r,t[i]);
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yi = S_MUL_ADD(fp->r,t[N4+i] ,fp->i,t[i]);
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*yp1 = yr;
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*yp2 = yi;
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fp++;
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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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#define OVERRIDE_clt_mdct_backward
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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, int arch)
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{
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int i;
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int N, N2, N4;
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const kiss_twiddle_scalar *trig;
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(void)arch;
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N = l->n;
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trig = l->trig;
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for (i=0;i<shift;i++)
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{
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N >>= 1;
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trig += N;
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}
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N2 = N>>1;
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N4 = N>>2;
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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 = out+(overlap>>1);
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const kiss_twiddle_scalar * OPUS_RESTRICT t = &trig[0];
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const opus_int16 * OPUS_RESTRICT bitrev = l->kfft[shift]->bitrev;
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for(i=0;i<N4;i++)
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{
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int rev;
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kiss_fft_scalar yr, yi;
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rev = *bitrev++;
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yr = S_MUL_ADD(*xp2, t[i] , *xp1, t[N4+i]);
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yi = S_MUL_SUB(*xp1, t[i] , *xp2, t[N4+i]);
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/* We swap real and imag because we use an FFT instead of an IFFT. */
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yp[2*rev+1] = yr;
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yp[2*rev] = yi;
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/* Storing the pre-rotation directly in the bitrev order. */
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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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opus_fft_impl(l->kfft[shift], (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 = &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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/* We swap real and imag because we're using an FFT instead of an IFFT. */
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re = yp0[1];
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im = yp0[0];
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t0 = t[i];
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t1 = t[N4+i];
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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_ADD(re,t0 , im,t1);
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yi = S_MUL_SUB(re,t1 , im,t0);
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/* We swap real and imag because we're using an FFT instead of an IFFT. */
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re = yp1[1];
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im = yp1[0];
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yp0[0] = yr;
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yp1[1] = yi;
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t0 = t[(N4-i-1)];
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t1 = t[(N2-i-1)];
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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_ADD(re,t0,im,t1);
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yi = S_MUL_SUB(re,t1,im,t0);
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yp1[0] = yr;
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yp0[1] = yi;
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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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}
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#endif /* __MDCT_MIPSR1_H__ */
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