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Fix a signed integer overflow #2

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Fix a signed integer overflow #2

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8 changes: 4 additions & 4 deletions sid.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -889,12 +889,12 @@ int SID::clock_resample_interpolate(cycle_count& delta_t, short* buf, int n,
sample_offset = next_sample_offset & FIXP_MASK;

int fir_offset = sample_offset*fir_RES >> FIXP_SHIFT;
int fir_offset_rmd = sample_offset*fir_RES & FIXP_MASK;
int64_t fir_offset_rmd = sample_offset*fir_RES & FIXP_MASK;
short* fir_start = fir + fir_offset*fir_N;
short* sample_start = sample + sample_index - fir_N + RINGSIZE;

// Convolution with filter impulse response.
int v1 = 0;
int64_t v1 = 0;
for (int j = 0; j < fir_N; j++) {
v1 += sample_start[j]*fir_start[j];
}
Expand All @@ -908,15 +908,15 @@ int SID::clock_resample_interpolate(cycle_count& delta_t, short* buf, int n,
fir_start = fir + fir_offset*fir_N;

// Convolution with filter impulse response.
int v2 = 0;
int64_t v2 = 0;
for (int j = 0; j < fir_N; j++) {
v2 += sample_start[j]*fir_start[j];
}

// Linear interpolation.
// fir_offset_rmd is equal for all samples, it can thus be factorized out:
// sum(v1 + rmd*(v2 - v1)) = sum(v1) + rmd*(sum(v2) - sum(v1))
int v = v1 + (fir_offset_rmd*(v2 - v1) >> FIXP_SHIFT);
int64_t v = v1 + (fir_offset_rmd*(v2 - v1) >> FIXP_SHIFT);

v >>= FIR_SHIFT;

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