From d9fb8a6651ea66f18f034fc70a51cfed17d3e12f Mon Sep 17 00:00:00 2001
From: Jean-Marc Valin <jmvalin@jmvalin.ca>
Date: Thu, 30 Jan 2014 11:16:24 -0500
Subject: [PATCH] Optimizing divisions with a signed numerator

---
 celt/bands.c   |  5 +++--
 celt/entcode.h | 12 ++++++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/celt/bands.c b/celt/bands.c
index 75f40787..0acb25c4 100644
--- a/celt/bands.c
+++ b/celt/bands.c
@@ -630,7 +630,8 @@ static int compute_qn(int N, int b, int offset, int pulse_cap, int stereo)
    /* 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 @@ void quant_all_bands(int encode, const CELTMode *m, int start, int end,
       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;
diff --git a/celt/entcode.h b/celt/entcode.h
index 66f281de..13d6c84e 100644
--- a/celt/entcode.h
+++ b/celt/entcode.h
@@ -137,4 +137,16 @@ static OPUS_INLINE opus_uint32 celt_udiv(opus_uint32 n, opus_uint32 d) {
 #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