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fixes overflows in celt_iir() by doing proper saturation

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This commit is contained in:
Jean-Marc Valin 2016-07-22 09:13:00 -04:00
parent 184a4767aa
commit a0bd7d3b84
4 changed files with 12 additions and 6 deletions
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1
celt/arch.h
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@ -206,6 +206,7 @@ static OPUS_INLINE int celt_isnan(float x)
#define SATURATE16(x) (x)
#define ROUND16(a,shift) (a)
#define SROUND16(a,shift) (a)
#define HALF16(x) (.5f*(x))
#define HALF32(x) (.5f*(x))

12
celt/celt_lpc.c
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@ -166,7 +166,7 @@ void celt_iir(const opus_val32 *_x,
{
mem[j]=mem[j-1];
}
mem[0] = ROUND16(sum,SIG_SHIFT);
mem[0] = SROUND16(sum, SIG_SHIFT);
_y[i] = sum;
}
#else
@ -195,20 +195,20 @@ void celt_iir(const opus_val32 *_x,
xcorr_kernel(rden, y+i, sum, ord, arch);
/* Patch up the result to compensate for the fact that this is an IIR */
y[i+ord ] = -ROUND16(sum[0],SIG_SHIFT);
y[i+ord ] = -SROUND16(sum[0],SIG_SHIFT);
_y[i ] = sum[0];
sum[1] = MAC16_16(sum[1], y[i+ord ], den[0]);
y[i+ord+1] = -ROUND16(sum[1],SIG_SHIFT);
y[i+ord+1] = -SROUND16(sum[1],SIG_SHIFT);
_y[i+1] = sum[1];
sum[2] = MAC16_16(sum[2], y[i+ord+1], den[0]);
sum[2] = MAC16_16(sum[2], y[i+ord ], den[1]);
y[i+ord+2] = -ROUND16(sum[2],SIG_SHIFT);
y[i+ord+2] = -SROUND16(sum[2],SIG_SHIFT);
_y[i+2] = sum[2];
sum[3] = MAC16_16(sum[3], y[i+ord+2], den[0]);
sum[3] = MAC16_16(sum[3], y[i+ord+1], den[1]);
sum[3] = MAC16_16(sum[3], y[i+ord ], den[2]);
y[i+ord+3] = -ROUND16(sum[3],SIG_SHIFT);
y[i+ord+3] = -SROUND16(sum[3],SIG_SHIFT);
_y[i+3] = sum[3];
}
for (;i<N;i++)
@ -216,7 +216,7 @@ void celt_iir(const opus_val32 *_x,
opus_val32 sum = _x[i];
for (j=0;j<ord;j++)
sum -= MULT16_16(rden[j],y[i+j]);
y[i+ord] = ROUND16(sum,SIG_SHIFT);
y[i+ord] = SROUND16(sum,SIG_SHIFT);
_y[i] = sum;
}
for(i=0;i<ord;i++)

2
celt/fixed_debug.h
View file

@ -233,6 +233,8 @@ static OPUS_INLINE int SHL32_(opus_int64 a, int shift, char *file, int line)
#define VSHR32(a, shift) (((shift)>0) ? SHR32(a, shift) : SHL32(a, -(shift)))
#define ROUND16(x,a) (celt_mips--,EXTRACT16(PSHR32((x),(a))))
#define SROUND16(x,a) (celt_mips--,EXTRACT16(SATURATE(PSHR32(x,a), 32767)));
#define HALF16(x) (SHR16(x,1))
#define HALF32(x) (SHR32(x,1))

3
celt/fixed_generic.h
View file

@ -104,6 +104,9 @@
/** Shift by a and round-to-neareast 32-bit value. Result is a 16-bit value */
#define ROUND16(x,a) (EXTRACT16(PSHR32((x),(a))))
/** Shift by a and round-to-neareast 32-bit value. Result is a saturated 16-bit value */
#define SROUND16(x,a) EXTRACT16(SATURATE(PSHR32(x,a), 32767));
/** Divide by two */
#define HALF16(x) (SHR16(x,1))
#define HALF32(x) (SHR32(x,1))