ref: 9fc8fc4cf432640f284113ba502ee027268b0d9f
dir: /celt/mdct.c/
/* 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"
#if defined(MIPSr1_ASM)
#include "mips/mdct_mipsr1.h"
#endif
#ifdef CUSTOM_MODES
int clt_mdct_init(mdct_lookup *l,int N, int maxshift, int arch)
{
int i;
kiss_twiddle_scalar *trig;
int shift;
int N2=N>>1;
l->n = N;
l->maxshift = maxshift;
for (i=0;i<=maxshift;i++)
{
if (i==0)
l->kfft[i] = opus_fft_alloc(N>>2>>i, 0, 0, arch);
else
l->kfft[i] = opus_fft_alloc_twiddles(N>>2>>i, 0, 0, l->kfft[0], arch);
#ifndef ENABLE_TI_DSPLIB55
if (l->kfft[i]==NULL)
return 0;
#endif
}
l->trig = trig = (kiss_twiddle_scalar*)opus_alloc((N-(N2>>maxshift))*sizeof(kiss_twiddle_scalar));
if (l->trig==NULL)
return 0;
for (shift=0;shift<=maxshift;shift++)
{
/* We have enough points that sine isn't necessary */
#if defined(FIXED_POINT)
#if 1
for (i=0;i<N2;i++)
trig[i] = TRIG_UPSCALE*celt_cos_norm(DIV32(ADD32(SHL32(EXTEND32(i),17),N2+16384),N));
#else
for (i=0;i<N2;i++)
trig[i] = (kiss_twiddle_scalar)MAX32(-32767,MIN32(32767,floor(.5+32768*cos(2*M_PI*(i+.125)/N))));
#endif
#else
for (i=0;i<N2;i++)
trig[i] = (kiss_twiddle_scalar)cos(2*PI*(i+.125)/N);
#endif
trig += N2;
N2 >>= 1;
N >>= 1;
}
return 1;
}
void clt_mdct_clear(mdct_lookup *l, int arch)
{
int i;
for (i=0;i<=l->maxshift;i++)
opus_fft_free(l->kfft[i], arch);
opus_free((kiss_twiddle_scalar*)l->trig);
}
#endif /* CUSTOM_MODES */
/* Forward MDCT trashes the input array */
#ifndef OVERRIDE_clt_mdct_forward
void clt_mdct_forward_c(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 arch)
{
int i;
int N, N2, N4;
VARDECL(kiss_fft_scalar, f);
VARDECL(kiss_fft_cpx, f2);
const kiss_fft_state *st = l->kfft[shift];
const kiss_twiddle_scalar *trig;
opus_val16 scale;
#ifdef FIXED_POINT
/* Allows us to scale with MULT16_32_Q16(), which is faster than
MULT16_32_Q15() on ARM. */
int scale_shift = st->scale_shift-1;
#endif
SAVE_STACK;
(void)arch;
scale = st->scale;
N = l->n;
trig = l->trig;
for (i=0;i<shift;i++)
{
N >>= 1;
trig += N;
}
N2 = N>>1;
N4 = N>>2;
ALLOC(f, N2, kiss_fft_scalar);
ALLOC(f2, N4, kiss_fft_cpx);
/* 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+3)>>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+3)>>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 = &trig[0];
for(i=0;i<N4;i++)
{
kiss_fft_cpx yc;
kiss_twiddle_scalar t0, t1;
kiss_fft_scalar re, im, yr, yi;
t0 = t[i];
t1 = t[N4+i];
re = *yp++;
im = *yp++;
yr = S_MUL(re,t0) - S_MUL(im,t1);
yi = S_MUL(im,t0) + S_MUL(re,t1);
yc.r = yr;
yc.i = yi;
yc.r = PSHR32(MULT16_32_Q16(scale, yc.r), scale_shift);
yc.i = PSHR32(MULT16_32_Q16(scale, yc.i), scale_shift);
f2[st->bitrev[i]] = yc;
}
}
/* N/4 complex FFT, does not downscale anymore */
opus_fft_impl(st, f2);
/* Post-rotate */
{
/* Temp pointers to make it really clear to the compiler what we're doing */
const kiss_fft_cpx * OPUS_RESTRICT fp = f2;
kiss_fft_scalar * OPUS_RESTRICT yp1 = out;
kiss_fft_scalar * OPUS_RESTRICT yp2 = out+stride*(N2-1);
const kiss_twiddle_scalar *t = &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->i,t[N4+i]) - S_MUL(fp->r,t[i]);
yi = S_MUL(fp->r,t[N4+i]) + S_MUL(fp->i,t[i]);
*yp1 = yr;
*yp2 = yi;
fp++;
yp1 += 2*stride;
yp2 -= 2*stride;
}
}
RESTORE_STACK;
}
#endif /* OVERRIDE_clt_mdct_forward */
#ifndef OVERRIDE_clt_mdct_backward
void clt_mdct_backward_c(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 arch)
{
int i;
int N, N2, N4;
const kiss_twiddle_scalar *trig;
(void) arch;
N = l->n;
trig = l->trig;
for (i=0;i<shift;i++)
{
N >>= 1;
trig += N;
}
N2 = N>>1;
N4 = N>>2;
/* 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 = out+(overlap>>1);
const kiss_twiddle_scalar * OPUS_RESTRICT t = &trig[0];
const opus_int16 * OPUS_RESTRICT bitrev = l->kfft[shift]->bitrev;
for(i=0;i<N4;i++)
{
int rev;
kiss_fft_scalar yr, yi;
rev = *bitrev++;
yr = ADD32_ovflw(S_MUL(*xp2, t[i]), S_MUL(*xp1, t[N4+i]));
yi = SUB32_ovflw(S_MUL(*xp1, t[i]), S_MUL(*xp2, t[N4+i]));
/* We swap real and imag because we use an FFT instead of an IFFT. */
yp[2*rev+1] = yr;
yp[2*rev] = yi;
/* Storing the pre-rotation directly in the bitrev order. */
xp1+=2*stride;
xp2-=2*stride;
}
}
opus_fft_impl(l->kfft[shift], (kiss_fft_cpx*)(out+(overlap>>1)));
/* Post-rotate and de-shuffle from both ends of the buffer at once to make
it in-place. */
{
kiss_fft_scalar * yp0 = out+(overlap>>1);
kiss_fft_scalar * yp1 = out+(overlap>>1)+N2-2;
const kiss_twiddle_scalar *t = &trig[0];
/* Loop to (N4+1)>>1 to handle odd N4. When N4 is odd, the
middle pair will be computed twice. */
for(i=0;i<(N4+1)>>1;i++)
{
kiss_fft_scalar re, im, yr, yi;
kiss_twiddle_scalar t0, t1;
/* We swap real and imag because we're using an FFT instead of an IFFT. */
re = yp0[1];
im = yp0[0];
t0 = t[i];
t1 = t[N4+i];
/* We'd scale up by 2 here, but instead it's done when mixing the windows */
yr = ADD32_ovflw(S_MUL(re,t0), S_MUL(im,t1));
yi = SUB32_ovflw(S_MUL(re,t1), S_MUL(im,t0));
/* We swap real and imag because we're using an FFT instead of an IFFT. */
re = yp1[1];
im = yp1[0];
yp0[0] = yr;
yp1[1] = yi;
t0 = t[(N4-i-1)];
t1 = t[(N2-i-1)];
/* We'd scale up by 2 here, but instead it's done when mixing the windows */
yr = ADD32_ovflw(S_MUL(re,t0), S_MUL(im,t1));
yi = SUB32_ovflw(S_MUL(re,t1), S_MUL(im,t0));
yp1[0] = yr;
yp0[1] = yi;
yp0 += 2;
yp1 -= 2;
}
}
/* Mirror on both sides for TDAC */
{
kiss_fft_scalar * OPUS_RESTRICT xp1 = out+overlap-1;
kiss_fft_scalar * OPUS_RESTRICT yp1 = out;
const opus_val16 * OPUS_RESTRICT wp1 = window;
const opus_val16 * OPUS_RESTRICT wp2 = window+overlap-1;
for(i = 0; i < overlap/2; i++)
{
kiss_fft_scalar x1, x2;
x1 = *xp1;
x2 = *yp1;
*yp1++ = SUB32_ovflw(MULT16_32_Q15(*wp2, x2), MULT16_32_Q15(*wp1, x1));
*xp1-- = ADD32_ovflw(MULT16_32_Q15(*wp1, x2), MULT16_32_Q15(*wp2, x1));
wp1++;
wp2--;
}
}
}
#endif /* OVERRIDE_clt_mdct_backward */