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Optimizing divisions with a signed numerator

--- a/celt/bands.c

+++ b/celt/bands.c

@@ -630,7 +630,8 @@

    /* The upper limit ensures that in a stereo split with itheta==16384, we'll

        always have enough bits left over to code at least one pulse in the

        side; otherwise it would collapse, since it doesn't get folded. */

-   qb = IMIN(b-pulse_cap-(4<<BITRES), (b+N2*offset)/N2);

+   qb = celt_sudiv(b+N2*offset, N2);

+   qb = IMIN(b-pulse_cap-(4<<BITRES), qb);

    qb = IMIN(8<<BITRES, qb);

@@ -1434,7 +1435,7 @@

       ctx.remaining_bits = remaining_bits;

       if (i <= codedBands-1)

       {

-         curr_balance = balance / IMIN(3, codedBands-i);

+         curr_balance = celt_sudiv(balance, IMIN(3, codedBands-i));

          b = IMAX(0, IMIN(16383, IMIN(remaining_bits+1,pulses[i]+curr_balance)));

       } else {

          b = 0;

--- a/celt/entcode.h

+++ b/celt/entcode.h

@@ -137,4 +137,16 @@

 #endif

 }

+static OPUS_INLINE opus_int32 celt_sudiv(opus_int32 n, opus_int32 d) {

+   celt_assert(d>0);

+#ifdef USE_SMALL_DIV_TABLE

+   if (n<0)

+      return -(opus_int32)celt_udiv(-n, d);

+   else

+      return celt_udiv(n, d);

+#else

+   return n/d;

+#endif

+}

+

 #endif