From ddea3a6fbfa5727e8d7c4d1a8943bb72862a90ee Mon Sep 17 00:00:00 2001
From: Jean-Marc Valin <jmvalin@jmvalin.ca>
Date: Sat, 18 Jun 2016 11:15:25 -0400
Subject: [PATCH] Fixes a fixed-point precision issue in remove_doubling()
This could lead to an integer overflow. Also, refactored the code a bit
---
celt/pitch.c | 65 +++++++++++++++++++++++++++++++---------------------
1 file changed, 39 insertions(+), 26 deletions(-)
diff --git a/celt/pitch.c b/celt/pitch.c
index 1d89cb034..873a09b8c 100644
--- a/celt/pitch.c
+++ b/celt/pitch.c
@@ -412,6 +412,41 @@ void pitch_search(const opus_val16 * OPUS_RESTRICT x_lp, opus_val16 * OPUS_RESTR
RESTORE_STACK;
}
+#ifdef FIXED_POINT
+static opus_val16 compute_pitch_gain(opus_val32 xy, opus_val32 xx, opus_val32 yy)
+{
+ opus_val32 x2y2;
+ int sx, sy, shift;
+ opus_val32 g;
+ opus_val16 den;
+ if (xy == 0 || xx == 0 || yy == 0)
+ return 0;
+ sx = celt_ilog2(xx)-14;
+ sy = celt_ilog2(yy)-14;
+ shift = sx + sy;
+ x2y2 = MULT16_16_Q14(VSHR32(xx, sx), VSHR32(yy, sy));
+ if (shift & 1) {
+ if (x2y2 < 32768)
+ {
+ x2y2 <<= 1;
+ shift--;
+ } else {
+ x2y2 >>= 1;
+ shift++;
+ }
+ }
+ den = celt_rsqrt_norm(x2y2);
+ g = MULT16_32_Q15(den, xy);
+ g = VSHR32(g, (shift>>1)-1);
+ return EXTRACT16(MIN32(g, Q15ONE));
+}
+#else
+static opus_val16 compute_pitch_gain(opus_val32 xy, opus_val32 xx, opus_val32 yy)
+{
+ return xy/celt_sqrt(1+xx*yy);
+}
+#endif
+
static const int second_check[16] = {0, 0, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2};
opus_val16 remove_doubling(opus_val16 *x, int maxperiod, int minperiod,
int N, int *T0_, int prev_period, opus_val16 prev_gain, int arch)
@@ -450,18 +485,7 @@ opus_val16 remove_doubling(opus_val16 *x, int maxperiod, int minperiod,
yy = yy_lookup[T0];
best_xy = xy;
best_yy = yy;
-#ifdef FIXED_POINT
- {
- opus_val32 x2y2;
- int sh, t;
- x2y2 = 1+HALF32(MULT32_32_Q31(xx,yy));
- sh = celt_ilog2(x2y2)>>1;
- t = VSHR32(x2y2, 2*(sh-7));
- g = g0 = VSHR32(MULT16_32_Q15(celt_rsqrt_norm(t), xy),sh+1);
- }
-#else
- g = g0 = xy/celt_sqrt(1+xx*yy);
-#endif
+ g = g0 = compute_pitch_gain(xy, xx, yy);
/* Look for any pitch at T/k */
for (k=2;k<=15;k++)
{
@@ -484,20 +508,9 @@ opus_val16 remove_doubling(opus_val16 *x, int maxperiod, int minperiod,
T1b = celt_udiv(2*second_check[k]*T0+k, 2*k);
}
dual_inner_prod(x, &x[-T1], &x[-T1b], N, &xy, &xy2, arch);
- xy += xy2;
- yy = yy_lookup[T1] + yy_lookup[T1b];
-#ifdef FIXED_POINT
- {
- opus_val32 x2y2;
- int sh, t;
- x2y2 = 1+MULT32_32_Q31(xx,yy);
- sh = celt_ilog2(x2y2)>>1;
- t = VSHR32(x2y2, 2*(sh-7));
- g1 = VSHR32(MULT16_32_Q15(celt_rsqrt_norm(t), xy),sh+1);
- }
-#else
- g1 = xy/celt_sqrt(1+2.f*xx*1.f*yy);
-#endif
+ xy = HALF32(xy + xy2);
+ yy = HALF32(yy_lookup[T1] + yy_lookup[T1b]);
+ g1 = compute_pitch_gain(xy, xx, yy);
if (abs(T1-prev_period)<=1)
cont = prev_gain;
else if (abs(T1-prev_period)<=2 && 5*k*k < T0)
--
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