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Fix log2_frac() to return an upper bound, not a lower bound.

--- a/libcelt/bands.c

+++ b/libcelt/bands.c

@@ -389,7 +389,7 @@

       tell = ec_enc_tell(enc, 4);

       if (i != 0)

          balance -= tell;

-      remaining_bits = (total_bits<<BITRES)-tell-2;

+      remaining_bits = (total_bits<<BITRES)-tell-1;

       curr_balance = (m->nbEBands-i);

       if (curr_balance > 3)

          curr_balance = 3;

@@ -472,7 +472,7 @@

       tell = ec_dec_tell(dec, 4);

       if (i != 0)

          balance -= tell;

-      remaining_bits = (total_bits<<BITRES)-tell-2;

+      remaining_bits = (total_bits<<BITRES)-tell-1;

       curr_balance = (m->nbEBands-i);

       if (curr_balance > 3)

          curr_balance = 3;

--- a/libcelt/cwrs.c

+++ b/libcelt/cwrs.c

@@ -54,6 +54,8 @@

    int i;

    /* EC_ILOG() actually returns log2()+1, go figure */

    int L = EC_ILOG(val)-1;

+   int pow2;

+   pow2=!(val&val-1);

    /*printf ("in: %d %d ", val, L);*/

    if (L>14)

       val >>= L-14;

@@ -67,9 +69,12 @@

       /*printf ("%d\n", val);*/

       if (val > 16384)

          L |= (1<<(frac-i-1));

-      else   

+      else

          val <<= 1;

 }

+   /*The previous loop returns a conservatively low estimate.

+     If val wasn't a power of two, we should round up.*/

+   L += !pow2;

    return L;

 }