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Simplified indexing in intra_prediction()

--- a/libcelt/vq.c

+++ b/libcelt/vq.c

@@ -279,25 +279,26 @@

    if (max_pos > MAX_INTRA)

       max_pos = MAX_INTRA;

+   /* Reverse the samples of x without reversing the channels */

    for (c=0;c<B;c++)

-   {

       for (j=0;j<N;j++)

-      {

          Xr[B*N-B*j-B+c] = x[B*j+c];

-      }

-   }

-   for (i=0;i<max_pos*B;i+=B)

+   for (i=0;i<max_pos;i++)

    {

       celt_word32_t xy=0, yy=0;

       celt_word32_t num;

       celt_word16_t den;

+      const celt_word16_t * restrict xp = Xr;

+      const celt_word16_t * restrict yp = Y+B*i;

       /* OPT: If this doesn't generate a double-MAC (on supported architectures),

          complain to your compilor vendor */

       j=0;

       do {

-         xy = MAC16_16(xy, Xr[B*N-j-1], Y[i+B*N-j-1]);

-         yy = MAC16_16(yy, Y[i+B*N-j-1], Y[i+B*N-j-1]);

+         xy = MAC16_16(xy, *xp, *yp);

+         yy = MAC16_16(yy, *yp, *yp);

+         xp++;

+         yp++;

       } while (++j<B*N); /* Promises we loop at least once */

       /* Using xy^2/yy as the score but without having to do the division */

       num = MULT16_16(ROUND16(xy,14),ROUND16(xy,14));

@@ -324,9 +325,9 @@

    /*printf ("%d %d ", sign, best);*/

    ec_enc_bits(enc,sign,1);

    if (max_pos == MAX_INTRA)

-      ec_enc_bits(enc,best/B,LOG_MAX_INTRA);

+      ec_enc_bits(enc,best,LOG_MAX_INTRA);

    else

-      ec_enc_uint(enc,best/B,max_pos);

+      ec_enc_uint(enc,best,max_pos);

    /*printf ("%d %f\n", best, best_score);*/

@@ -339,7 +340,7 @@

    {

       for (j=0;j<N;j++)

       {

-         P[B*j+c] = s*Y[best+B*(N-j-1)+c];

+         P[B*j+c] = s*Y[B*best+B*(N-j-1)+c];

          E = MAC16_16(E, P[j],P[j]);

       }

    }