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Moving bitrev step to forward MDCT too

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This commit is contained in:
Jean-Marc Valin 2013-12-21 14:29:41 -05:00
parent bc13bbaad7
commit 99968abba8
3 changed files with 63 additions and 36 deletions
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56
celt/kiss_fft.c
View file

@ -600,7 +600,7 @@ void opus_fft_free(const kiss_fft_state *cfg)
#endif /* CUSTOM_MODES */
void opus_fft(const kiss_fft_state *st,const kiss_fft_cpx *fin,kiss_fft_cpx *fout)
void opus_fft_impl(const kiss_fft_state *st,kiss_fft_cpx *fout)
{
int m2, m;
int p;
@ -608,34 +608,10 @@ void opus_fft(const kiss_fft_state *st,const kiss_fft_cpx *fin,kiss_fft_cpx *fou
int fstride[MAXFACTORS];
int i;
int shift;
#ifdef FIXED_POINT
/* FIXME: This should eventually just go in the state. */
opus_val16 scale;
int scale_shift;
scale_shift = celt_ilog2(st->nfft);
if (st->nfft == 1<<scale_shift)
scale = Q15ONE;
else
scale = (1073741824+st->nfft/2)/st->nfft>>(15-scale_shift);
#endif
/* st->shift can be -1 */
shift = st->shift>0 ? st->shift : 0;
celt_assert2 (fin != fout, "In-place FFT not supported");
/* Bit-reverse the input */
for (i=0;i<st->nfft;i++)
{
kiss_fft_cpx x = fin[i];
#ifdef FIXED_POINT
fout[st->bitrev[i]].r = SHR32(MULT16_32_Q15(scale, x.r), scale_shift);
fout[st->bitrev[i]].i = SHR32(MULT16_32_Q15(scale, x.i), scale_shift);
#else
fout[st->bitrev[i]].r = st->scale*x.r;
fout[st->bitrev[i]].i = st->scale*x.i;
#endif
}
fstride[0] = 1;
L=0;
do {
@ -672,6 +648,36 @@ void opus_fft(const kiss_fft_state *st,const kiss_fft_cpx *fin,kiss_fft_cpx *fou
}
}
void opus_fft(const kiss_fft_state *st,const kiss_fft_cpx *fin,kiss_fft_cpx *fout)
{
int i;
#ifdef FIXED_POINT
/* FIXME: This should eventually just go in the state. */
opus_val16 scale;
int scale_shift;
scale_shift = celt_ilog2(st->nfft);
if (st->nfft == 1<<scale_shift)
scale = Q15ONE;
else
scale = (1073741824+st->nfft/2)/st->nfft>>(15-scale_shift);
#endif
celt_assert2 (fin != fout, "In-place FFT not supported");
/* Bit-reverse the input */
for (i=0;i<st->nfft;i++)
{
kiss_fft_cpx x = fin[i];
#ifdef FIXED_POINT
fout[st->bitrev[i]].r = SHR32(MULT16_32_Q15(scale, x.r), scale_shift);
fout[st->bitrev[i]].i = SHR32(MULT16_32_Q15(scale, x.i), scale_shift);
#else
fout[st->bitrev[i]].r = st->scale*x.r;
fout[st->bitrev[i]].i = st->scale*x.i;
#endif
}
opus_fft_impl(st, fout);
}
void opus_ifft_impl(const kiss_fft_state *st,kiss_fft_cpx *fout)
{
int m2, m;

1
celt/kiss_fft.h
View file

@ -130,6 +130,7 @@ kiss_fft_state *opus_fft_alloc(int nfft,void * mem,size_t * lenmem);
void opus_fft(const kiss_fft_state *cfg,const kiss_fft_cpx *fin,kiss_fft_cpx *fout);
void opus_ifft(const kiss_fft_state *cfg,const kiss_fft_cpx *fin,kiss_fft_cpx *fout);
void opus_fft_impl(const kiss_fft_state *st,kiss_fft_cpx *fout);
void opus_ifft_impl(const kiss_fft_state *st,kiss_fft_cpx *fout);
void opus_fft_free(const kiss_fft_state *cfg);

42
celt/mdct.c
View file

@ -109,14 +109,25 @@ void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar
int N, N2, N4;
kiss_twiddle_scalar sine;
VARDECL(kiss_fft_scalar, f);
VARDECL(kiss_fft_scalar, f2);
VARDECL(kiss_fft_cpx, f2);
const kiss_fft_state *st = l->kfft[shift];
#ifdef FIXED_POINT
/* FIXME: This should eventually just go in the state. */
opus_val16 scale;
int scale_shift;
scale_shift = celt_ilog2(st->nfft);
if (st->nfft == 1<<scale_shift)
scale = Q15ONE;
else
scale = (1073741824+st->nfft/2)/st->nfft>>(15-scale_shift);
#endif
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);
ALLOC(f2, N2, kiss_fft_cpx);
/* sin(x) ~= x here */
#ifdef FIXED_POINT
sine = TRIG_UPSCALE*(QCONST16(0.7853981f, 15)+N2)/N;
@ -170,24 +181,33 @@ void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar
const kiss_twiddle_scalar *t = &l->trig[0];
for(i=0;i<N4;i++)
{
kiss_fft_cpx yc;
kiss_fft_scalar re, im, yr, yi;
re = yp[0];
im = yp[1];
re = *yp++;
im = *yp++;
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);
yc.r = yr + S_MUL(yi,sine);
yc.i = yi - S_MUL(yr,sine);
#ifdef FIXED_POINT
yc.r = SHR32(MULT16_32_Q15(scale, yc.r), scale_shift);
yc.i = SHR32(MULT16_32_Q15(scale, yc.i), scale_shift);
#else
yc.r *= st->scale;
yc.i *= st->scale;
#endif
f2[st->bitrev[i]] = yc;
}
}
/* N/4 complex FFT, down-scales by 4/N */
opus_fft(l->kfft[shift], (kiss_fft_cpx *)f, (kiss_fft_cpx *)f2);
opus_fft_impl(st, f2);
/* Post-rotate */
{
/* Temp pointers to make it really clear to the compiler what we're doing */
const kiss_fft_scalar * OPUS_RESTRICT fp = f2;
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 = &l->trig[0];
@ -195,12 +215,12 @@ void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar
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]);
yr = S_MUL(fp->i,t[(N4-i)<<shift]) + S_MUL(fp->r,t[i<<shift]);
yi = S_MUL(fp->r,t[(N4-i)<<shift]) - S_MUL(fp->i,t[i<<shift]);
/* works because the cos is nearly one */
*yp1 = yr - S_MUL(yi,sine);
*yp2 = yi + S_MUL(yr,sine);;
fp += 2;
fp++;
yp1 += 2*stride;
yp2 -= 2*stride;
}