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-rw-r--r--celt/mdct.c113
1 files changed, 46 insertions, 67 deletions
diff --git a/celt/mdct.c b/celt/mdct.c
index 16a36c6..90a214a 100644
--- a/celt/mdct.c
+++ b/celt/mdct.c
@@ -109,12 +109,14 @@ 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);
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;
@@ -131,7 +133,7 @@ void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar
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++)
+ 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);
@@ -143,7 +145,7 @@ void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar
}
wp1 = window;
wp2 = window+overlap-1;
- for(;i<N4-(overlap>>2);i++)
+ for(;i<N4-((overlap+3)>>2);i++)
{
/* Real part arranged as a-bR, Imag part arranged as -c-dR */
*yp++ = *xp2;
@@ -180,12 +182,12 @@ void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar
}
/* N/4 complex FFT, down-scales by 4/N */
- opus_fft(l->kfft[shift], (kiss_fft_cpx *)f, (kiss_fft_cpx *)in);
+ opus_fft(l->kfft[shift], (kiss_fft_cpx *)f, (kiss_fft_cpx *)f2);
/* Post-rotate */
{
/* Temp pointers to make it really clear to the compiler what we're doing */
- const kiss_fft_scalar * OPUS_RESTRICT fp = in;
+ const kiss_fft_scalar * 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];
@@ -212,14 +214,12 @@ void clt_mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scala
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
@@ -249,81 +249,60 @@ void clt_mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scala
}
/* 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);
+ opus_ifft(l->kfft[shift], (kiss_fft_cpx *)f2, (kiss_fft_cpx *)(out+(overlap>>1)));
- /* Post-rotate */
+ /* Post-rotate and de-shuffle from both ends of the buffer at once to make
+ it in-place. */
{
- kiss_fft_scalar * OPUS_RESTRICT fp = f;
+ kiss_fft_scalar * OPUS_RESTRICT yp0 = out+(overlap>>1);
+ kiss_fft_scalar * OPUS_RESTRICT yp1 = out+(overlap>>1)+N2-2;
const kiss_twiddle_scalar *t = &l->trig[0];
-
- for(i=0;i<N4;i++)
+ /* 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;
- re = fp[0];
- im = fp[1];
+ kiss_twiddle_scalar t0, t1;
+ re = yp0[0];
+ im = yp0[1];
+ t0 = t[i<<shift];
+ t1 = t[(N4-i)<<shift];
/* 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]);
+ yr = S_MUL(re,t0) - S_MUL(im,t1);
+ yi = S_MUL(im,t0) + S_MUL(re,t1);
+ re = yp1[0];
+ im = yp1[1];
/* 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;
+ yp0[0] = -(yr - S_MUL(yi,sine));
+ yp1[1] = yi + S_MUL(yr,sine);
+
+ t0 = t[(N4-i-1)<<shift];
+ t1 = t[(i+1)<<shift];
+ /* We'd scale up by 2 here, but instead it's done when mixing the windows */
+ yr = S_MUL(re,t0) - S_MUL(im,t1);
+ yi = S_MUL(im,t0) + S_MUL(re,t1);
+ /* works because the cos is nearly one */
+ yp1[0] = -(yr - S_MUL(yi,sine));
+ yp0[1] = yi + S_MUL(yr,sine);
+ yp0 += 2;
+ yp1 -= 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);
+ 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< N4-overlap/2; i++)
- {
- *xp2 = *fp2;
- xp2++;
- fp2++;
- }
- for(; i < N4; i++)
+
+ for(i = 0; i < overlap/2; i++)
{
- kiss_fft_scalar x2;
- x2 = *fp2++;
- *yp2-- = MULT16_32_Q15(*wp1, x2);
- *xp2++ = MULT16_32_Q15(*wp2, x2);
+ kiss_fft_scalar x1, x2;
+ x1 = *xp1;
+ x2 = *yp1;
+ *yp1++ = MULT16_32_Q15(*wp2, x2) - MULT16_32_Q15(*wp1, x1);
+ *xp1-- = MULT16_32_Q15(*wp1, x2) + MULT16_32_Q15(*wp2, x1);
wp1++;
wp2--;
}
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