Save more integer divisions on ARM when we know the operands are positive

5 files changed, 18 insertions, 13 deletions

diff --git a/celt/bands.c b/celt/bands.c
index 7e1d97eb..75f40787 100644
--- a/celt/bands.c
+++ b/celt/bands.c
@@ -281,7 +281,8 @@ void anti_collapse(const CELTMode *m, celt_norm *X_, unsigned char *collapse_mas
 
       N0 = m->eBands[i+1]-m->eBands[i];
       /* depth in 1/8 bits */
-      depth = (1+pulses[i])/((m->eBands[i+1]-m->eBands[i])<<LM);
+      celt_assert(pulses[i]>=0);
+      depth = celt_udiv(1+pulses[i], (m->eBands[i+1]-m->eBands[i])<<LM);
 
 #ifdef FIXED_POINT
       thresh32 = SHR32(celt_exp2(-SHL16(depth, 10-BITRES)),1);
@@ -491,7 +492,7 @@ int spreading_decision(const CELTMode *m, const celt_norm *X, int *average,
 
          /* Only include four last bands (8 kHz and up) */
          if (i>m->nbEBands-4)
-            hf_sum += 32*(tcount[1]+tcount[0])/N;
+            hf_sum += celt_udiv(32*(tcount[1]+tcount[0]), N);
          tmp = (2*tcount[2] >= N) + (2*tcount[1] >= N) + (2*tcount[0] >= N);
          sum += tmp*256;
          nbBands++;
@@ -501,7 +502,7 @@ int spreading_decision(const CELTMode *m, const celt_norm *X, int *average,
    if (update_hf)
    {
       if (hf_sum)
-         hf_sum /= C*(4-m->nbEBands+end);
+         hf_sum = celt_udiv(hf_sum, C*(4-m->nbEBands+end));
       *hf_average = (*hf_average+hf_sum)>>1;
       hf_sum = *hf_average;
       if (*tapset_decision==2)
@@ -517,7 +518,8 @@ int spreading_decision(const CELTMode *m, const celt_norm *X, int *average,
    }
    /*printf("%d %d %d\n", hf_sum, *hf_average, *tapset_decision);*/
    celt_assert(nbBands>0); /* end has to be non-zero */
-   sum /= nbBands;
+   celt_assert(sum>=0);
+   sum = celt_udiv(sum, nbBands);
    /* Recursive averaging */
    sum = (sum+*average)>>1;
    *average = sum;
@@ -775,7 +777,8 @@ static void compute_theta(struct band_ctx *ctx, struct split_ctx *sctx,
             ec_dec_update(ec, fl, fl+fs, ft);
          }
       }
-      itheta = (opus_int32)itheta*16384/qn;
+      celt_assert(itheta>=0);
+      itheta = celt_udiv((opus_int32)itheta*16384, qn);
       if (encode && stereo)
       {
          if (itheta==0)
@@ -1089,7 +1092,7 @@ static unsigned quant_band(struct band_ctx *ctx, celt_norm *X,
 
    longBlocks = B0==1;
 
-   N_B /= B;
+   N_B = celt_udiv(N_B, B);
 
    /* Special case for one sample */
    if (N==1)
diff --git a/celt/entcode.h b/celt/entcode.h
index c10fe8d7..66f281de 100644
--- a/celt/entcode.h
+++ b/celt/entcode.h
@@ -122,6 +122,7 @@ opus_uint32 ec_tell_frac(ec_ctx *_this);
 
 /* Tested exhaustively for all n and for 1<=d<=256 */
 static OPUS_INLINE opus_uint32 celt_udiv(opus_uint32 n, opus_uint32 d) {
+   celt_assert(d>0);
 #ifdef USE_SMALL_DIV_TABLE
    if (d>256)
       return n/d;
diff --git a/celt/pitch.c b/celt/pitch.c
index d4037892..2f0b14b7 100644
--- a/celt/pitch.c
+++ b/celt/pitch.c
@@ -460,7 +460,7 @@ opus_val16 remove_doubling(opus_val16 *x, int maxperiod, int minperiod,
       opus_val16 g1;
       opus_val16 cont=0;
       opus_val16 thresh;
-      T1 = (2*T0+k)/(2*k);
+      T1 = celt_udiv(2*T0+k, 2*k);
       if (T1 < minperiod)
          break;
       /* Look for another strong correlation at T1b */
@@ -472,7 +472,7 @@ opus_val16 remove_doubling(opus_val16 *x, int maxperiod, int minperiod,
             T1b = T0+T1;
       } else
       {
-         T1b = (2*second_check[k]*T0+k)/(2*k);
+         T1b = celt_udiv(2*second_check[k]*T0+k, 2*k);
       }
       dual_inner_prod(x, &x[-T1], &x[-T1b], N, &xy, &xy2);
       xy += xy2;
diff --git a/celt/rate.c b/celt/rate.c
index e13d839d..f2e49a53 100644
--- a/celt/rate.c
+++ b/celt/rate.c
@@ -333,7 +333,7 @@ static OPUS_INLINE int interp_bits2pulses(const CELTMode *m, int start, int end,
       /*Figure out how many left-over bits we would be adding to this band.
         This can include bits we've stolen back from higher, skipped bands.*/
       left = total-psum;
-      percoeff = left/(m->eBands[codedBands]-m->eBands[start]);
+      percoeff = celt_udiv(left, m->eBands[codedBands]-m->eBands[start]);
       left -= (m->eBands[codedBands]-m->eBands[start])*percoeff;
       rem = IMAX(left-(m->eBands[j]-m->eBands[start]),0);
       band_width = m->eBands[codedBands]-m->eBands[j];
@@ -414,7 +414,7 @@ static OPUS_INLINE int interp_bits2pulses(const CELTMode *m, int start, int end,
 
    /* Allocate the remaining bits */
    left = total-psum;
-   percoeff = left/(m->eBands[codedBands]-m->eBands[start]);
+   percoeff = celt_udiv(left, m->eBands[codedBands]-m->eBands[start]);
    left -= (m->eBands[codedBands]-m->eBands[start])*percoeff;
    for (j=start;j<codedBands;j++)
       bits[j] += ((int)percoeff*(m->eBands[j+1]-m->eBands[j]));
@@ -465,7 +465,8 @@ static OPUS_INLINE int interp_bits2pulses(const CELTMode *m, int start, int end,
             offset += NClogN>>3;
 
          /* Divide with rounding */
-         ebits[j] = IMAX(0, (bits[j] + offset + (den<<(BITRES-1))) / (den<<BITRES));
+         ebits[j] = IMAX(0, (bits[j] + offset + (den<<(BITRES-1))));
+         ebits[j] = celt_udiv(ebits[j], den<<BITRES);
 
          /* Make sure not to bust */
          if (C*ebits[j] > (bits[j]>>BITRES))
diff --git a/celt/vq.c b/celt/vq.c
index 7d922467..914ec861 100644
--- a/celt/vq.c
+++ b/celt/vq.c
@@ -94,7 +94,7 @@ static void exp_rotation(celt_norm *X, int len, int dir, int stride, int K, int
    }
    /*NOTE: As a minor optimization, we could be passing around log2(B), not B, for both this and for
       extract_collapse_mask().*/
-   len /= stride;
+   len = celt_udiv(len, stride);
    for (i=0;i<stride;i++)
    {
       if (dir < 0)
@@ -143,7 +143,7 @@ static unsigned extract_collapse_mask(int *iy, int N, int B)
       return 1;
    /*NOTE: As a minor optimization, we could be passing around log2(B), not B, for both this and for
       exp_rotation().*/
-   N0 = N/B;
+   N0 = celt_udiv(N, B);
    collapse_mask = 0;
    i=0; do {
       int j;