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+/* Copyright (c) 2007-2008 CSIRO
+ Copyright (c) 2007-2008 Xiph.Org Foundation
+ Written by Jean-Marc Valin */
+/*
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions
+ are met:
+
+ - Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+
+ - Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions and the following disclaimer in the
+ documentation and/or other materials provided with the distribution.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+ OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+/* This is a simple MDCT implementation that uses a N/4 complex FFT
+ to do most of the work. It should be relatively straightforward to
+ plug in pretty much and FFT here.
+
+ This replaces the Vorbis FFT (and uses the exact same API), which
+ was a bit too messy and that was ending up duplicating code
+ (might as well use the same FFT everywhere).
+
+ The algorithm is similar to (and inspired from) Fabrice Bellard's
+ MDCT implementation in FFMPEG, but has differences in signs, ordering
+ and scaling in many places.
+*/
+
+#ifndef SKIP_CONFIG_H
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+#endif
+
+#include "mdct.h"
+#include "kiss_fft.h"
+#include "_kiss_fft_guts.h"
+#include <math.h>
+#include "os_support.h"
+#include "mathops.h"
+#include "stack_alloc.h"
+
+#ifdef CUSTOM_MODES
+
+int clt_mdct_init(mdct_lookup *l,int N, int maxshift)
+{
+ int i;
+ int N4;
+ kiss_twiddle_scalar *trig;
+#if defined(FIXED_POINT)
+ int N2=N>>1;
+#endif
+ l->n = N;
+ N4 = N>>2;
+ l->maxshift = maxshift;
+ for (i=0;i<=maxshift;i++)
+ {
+ if (i==0)
+ l->kfft[i] = opus_fft_alloc(N>>2>>i, 0, 0);
+ else
+ l->kfft[i] = opus_fft_alloc_twiddles(N>>2>>i, 0, 0, l->kfft[0]);
+#ifndef ENABLE_TI_DSPLIB55
+ if (l->kfft[i]==NULL)
+ return 0;
+#endif
+ }
+ l->trig = trig = (kiss_twiddle_scalar*)opus_alloc((N4+1)*sizeof(kiss_twiddle_scalar));
+ if (l->trig==NULL)
+ return 0;
+ /* We have enough points that sine isn't necessary */
+#if defined(FIXED_POINT)
+ for (i=0;i<=N4;i++)
+ trig[i] = TRIG_UPSCALE*celt_cos_norm(DIV32(ADD32(SHL32(EXTEND32(i),17),N2),N));
+#else
+ for (i=0;i<=N4;i++)
+ trig[i] = (kiss_twiddle_scalar)cos(2*PI*i/N);
+#endif
+ return 1;
+}
+
+void clt_mdct_clear(mdct_lookup *l)
+{
+ int i;
+ for (i=0;i<=l->maxshift;i++)
+ opus_fft_free(l->kfft[i]);
+ opus_free((kiss_twiddle_scalar*)l->trig);
+}
+
+#endif /* CUSTOM_MODES */
+
+/* Forward MDCT trashes the input array */
+void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * OPUS_RESTRICT out,
+ const opus_val16 *window, int overlap, int shift, int stride)
+{
+ int i;
+ int N, N2, N4;
+ kiss_twiddle_scalar sine;
+ VARDECL(kiss_fft_scalar, f);
+ SAVE_STACK;
+ N = l->n;
+ N >>= shift;
+ N2 = N>>1;
+ N4 = N>>2;
+ ALLOC(f, N2, kiss_fft_scalar);
+ /* sin(x) ~= x here */
+#ifdef FIXED_POINT
+ sine = TRIG_UPSCALE*(QCONST16(0.7853981f, 15)+N2)/N;
+#else
+ sine = (kiss_twiddle_scalar)2*PI*(.125f)/N;
+#endif
+
+ /* Consider the input to be composed of four blocks: [a, b, c, d] */
+ /* Window, shuffle, fold */
+ {
+ /* Temp pointers to make it really clear to the compiler what we're doing */
+ const kiss_fft_scalar * OPUS_RESTRICT xp1 = in+(overlap>>1);
+ const kiss_fft_scalar * OPUS_RESTRICT xp2 = in+N2-1+(overlap>>1);
+ kiss_fft_scalar * OPUS_RESTRICT yp = f;
+ const opus_val16 * OPUS_RESTRICT wp1 = window+(overlap>>1);
+ const opus_val16 * OPUS_RESTRICT wp2 = window+(overlap>>1)-1;
+ for(i=0;i<(overlap>>2);i++)
+ {
+ /* Real part arranged as -d-cR, Imag part arranged as -b+aR*/
+ *yp++ = MULT16_32_Q15(*wp2, xp1[N2]) + MULT16_32_Q15(*wp1,*xp2);
+ *yp++ = MULT16_32_Q15(*wp1, *xp1) - MULT16_32_Q15(*wp2, xp2[-N2]);
+ xp1+=2;
+ xp2-=2;
+ wp1+=2;
+ wp2-=2;
+ }
+ wp1 = window;
+ wp2 = window+overlap-1;
+ for(;i<N4-(overlap>>2);i++)
+ {
+ /* Real part arranged as a-bR, Imag part arranged as -c-dR */
+ *yp++ = *xp2;
+ *yp++ = *xp1;
+ xp1+=2;
+ xp2-=2;
+ }
+ for(;i<N4;i++)
+ {
+ /* Real part arranged as a-bR, Imag part arranged as -c-dR */
+ *yp++ = -MULT16_32_Q15(*wp1, xp1[-N2]) + MULT16_32_Q15(*wp2, *xp2);
+ *yp++ = MULT16_32_Q15(*wp2, *xp1) + MULT16_32_Q15(*wp1, xp2[N2]);
+ xp1+=2;
+ xp2-=2;
+ wp1+=2;
+ wp2-=2;
+ }
+ }
+ /* Pre-rotation */
+ {
+ kiss_fft_scalar * OPUS_RESTRICT yp = f;
+ const kiss_twiddle_scalar *t = &l->trig[0];
+ for(i=0;i<N4;i++)
+ {
+ kiss_fft_scalar re, im, yr, yi;
+ re = yp[0];
+ im = yp[1];
+ yr = -S_MUL(re,t[i<<shift]) - S_MUL(im,t[(N4-i)<<shift]);
+ yi = -S_MUL(im,t[i<<shift]) + S_MUL(re,t[(N4-i)<<shift]);
+ /* works because the cos is nearly one */
+ *yp++ = yr + S_MUL(yi,sine);
+ *yp++ = yi - S_MUL(yr,sine);
+ }
+ }
+
+ /* N/4 complex FFT, down-scales by 4/N */
+ opus_fft(l->kfft[shift], (kiss_fft_cpx *)f, (kiss_fft_cpx *)in);
+
+ /* Post-rotate */
+ {
+ /* Temp pointers to make it really clear to the compiler what we're doing */
+ const kiss_fft_scalar * OPUS_RESTRICT fp = in;
+ kiss_fft_scalar * OPUS_RESTRICT yp1 = out;
+ kiss_fft_scalar * OPUS_RESTRICT yp2 = out+stride*(N2-1);
+ const kiss_twiddle_scalar *t = &l->trig[0];
+ /* Temp pointers to make it really clear to the compiler what we're doing */
+ for(i=0;i<N4;i++)
+ {
+ kiss_fft_scalar yr, yi;
+ yr = S_MUL(fp[1],t[(N4-i)<<shift]) + S_MUL(fp[0],t[i<<shift]);
+ yi = S_MUL(fp[0],t[(N4-i)<<shift]) - S_MUL(fp[1],t[i<<shift]);
+ /* works because the cos is nearly one */
+ *yp1 = yr - S_MUL(yi,sine);
+ *yp2 = yi + S_MUL(yr,sine);;
+ fp += 2;
+ yp1 += 2*stride;
+ yp2 -= 2*stride;
+ }
+ }
+ RESTORE_STACK;
+}
+
+void clt_mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * OPUS_RESTRICT out,
+ const opus_val16 * OPUS_RESTRICT window, int overlap, int shift, int stride)
+{
+ int i;
+ int N, N2, N4;
+ kiss_twiddle_scalar sine;
+ VARDECL(kiss_fft_scalar, f);
+ VARDECL(kiss_fft_scalar, f2);
+ SAVE_STACK;
+ N = l->n;
+ N >>= shift;
+ N2 = N>>1;
+ N4 = N>>2;
+ ALLOC(f, N2, kiss_fft_scalar);
+ ALLOC(f2, N2, kiss_fft_scalar);
+ /* sin(x) ~= x here */
+#ifdef FIXED_POINT
+ sine = TRIG_UPSCALE*(QCONST16(0.7853981f, 15)+N2)/N;
+#else
+ sine = (kiss_twiddle_scalar)2*PI*(.125f)/N;
+#endif
+
+ /* Pre-rotate */
+ {
+ /* Temp pointers to make it really clear to the compiler what we're doing */
+ const kiss_fft_scalar * OPUS_RESTRICT xp1 = in;
+ const kiss_fft_scalar * OPUS_RESTRICT xp2 = in+stride*(N2-1);
+ kiss_fft_scalar * OPUS_RESTRICT yp = f2;
+ const kiss_twiddle_scalar *t = &l->trig[0];
+ for(i=0;i<N4;i++)
+ {
+ kiss_fft_scalar yr, yi;
+ yr = -S_MUL(*xp2, t[i<<shift]) + S_MUL(*xp1,t[(N4-i)<<shift]);
+ yi = -S_MUL(*xp2, t[(N4-i)<<shift]) - S_MUL(*xp1,t[i<<shift]);
+ /* works because the cos is nearly one */
+ *yp++ = yr - S_MUL(yi,sine);
+ *yp++ = yi + S_MUL(yr,sine);
+ xp1+=2*stride;
+ xp2-=2*stride;
+ }
+ }
+
+ /* Inverse N/4 complex FFT. This one should *not* downscale even in fixed-point */
+ opus_ifft(l->kfft[shift], (kiss_fft_cpx *)f2, (kiss_fft_cpx *)f);
+
+ /* Post-rotate */
+ {
+ kiss_fft_scalar * OPUS_RESTRICT fp = f;
+ const kiss_twiddle_scalar *t = &l->trig[0];
+
+ for(i=0;i<N4;i++)
+ {
+ kiss_fft_scalar re, im, yr, yi;
+ re = fp[0];
+ im = fp[1];
+ /* We'd scale up by 2 here, but instead it's done when mixing the windows */
+ yr = S_MUL(re,t[i<<shift]) - S_MUL(im,t[(N4-i)<<shift]);
+ yi = S_MUL(im,t[i<<shift]) + S_MUL(re,t[(N4-i)<<shift]);
+ /* works because the cos is nearly one */
+ *fp++ = yr - S_MUL(yi,sine);
+ *fp++ = yi + S_MUL(yr,sine);
+ }
+ }
+ /* De-shuffle the components for the middle of the window only */
+ {
+ const kiss_fft_scalar * OPUS_RESTRICT fp1 = f;
+ const kiss_fft_scalar * OPUS_RESTRICT fp2 = f+N2-1;
+ kiss_fft_scalar * OPUS_RESTRICT yp = f2;
+ for(i = 0; i < N4; i++)
+ {
+ *yp++ =-*fp1;
+ *yp++ = *fp2;
+ fp1 += 2;
+ fp2 -= 2;
+ }
+ }
+ out -= (N2-overlap)>>1;
+ /* Mirror on both sides for TDAC */
+ {
+ kiss_fft_scalar * OPUS_RESTRICT fp1 = f2+N4-1;
+ kiss_fft_scalar * OPUS_RESTRICT xp1 = out+N2-1;
+ kiss_fft_scalar * OPUS_RESTRICT yp1 = out+N4-overlap/2;
+ const opus_val16 * OPUS_RESTRICT wp1 = window;
+ const opus_val16 * OPUS_RESTRICT wp2 = window+overlap-1;
+ for(i = 0; i< N4-overlap/2; i++)
+ {
+ *xp1 = *fp1;
+ xp1--;
+ fp1--;
+ }
+ for(; i < N4; i++)
+ {
+ kiss_fft_scalar x1;
+ x1 = *fp1--;
+ *yp1++ +=-MULT16_32_Q15(*wp1, x1);
+ *xp1-- += MULT16_32_Q15(*wp2, x1);
+ wp1++;
+ wp2--;
+ }
+ }
+ {
+ kiss_fft_scalar * OPUS_RESTRICT fp2 = f2+N4;
+ kiss_fft_scalar * OPUS_RESTRICT xp2 = out+N2;
+ kiss_fft_scalar * OPUS_RESTRICT yp2 = out+N-1-(N4-overlap/2);
+ const opus_val16 * OPUS_RESTRICT wp1 = window;
+ const opus_val16 * OPUS_RESTRICT wp2 = window+overlap-1;
+ for(i = 0; i< N4-overlap/2; i++)
+ {
+ *xp2 = *fp2;
+ xp2++;
+ fp2++;
+ }
+ for(; i < N4; i++)
+ {
+ kiss_fft_scalar x2;
+ x2 = *fp2++;
+ *yp2-- = MULT16_32_Q15(*wp1, x2);
+ *xp2++ = MULT16_32_Q15(*wp2, x2);
+ wp1++;
+ wp2--;
+ }
+ }
+ RESTORE_STACK;
+}
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