Updating Opus to a pre-release of 1.1

celt/mdct.c

Index: celt/mdct.c
diff --git a/celt/mdct.c b/celt/mdct.c
index 16a36c692f9b35b50971516ec249f51d1c71216c..90a214ad0e617a7d258f2aa61a07739d6ef9d7c4 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--;
       }