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sigProcLib: Use explicit NaN check in sinc table generation 

Using "x < 0.01" is a crude check for detecting NaN condition, which
occurs in a sinc call when x = 0 due to divide-by-zero. Use stdlib
isnan() call for this purpose. Also, as the table is created only
once during initialization, use double floats for table value
generation.

Change-Id: I3a838fe3139fa977dfe906246020a14451185714
This commit is contained in:
Tom Tsou 2017-06-16 17:14:31 -07:00 committed by Tom Tsou
parent bb0c68ae61
commit a3dce85ffc
1 changed files with 3 additions and 9 deletions
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12
Transceiver52M/sigProcLib.cpp
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@ -979,16 +979,10 @@ signalVector *modulateBurst(const BitVector &wBurst, int guardPeriodLength,
static void generateSincTable()
{
float x;
for (int i = 0; i < TABLESIZE; i++) {
x = (float) i / TABLESIZE * 8 * M_PI;
if (fabs(x) < 0.01) {
sincTable[i] = 1.0f;
continue;
}
sincTable[i] = sinf(x) / x;
auto x = (double) i / TABLESIZE * 8 * M_PI;
auto y = sin(x) / x;
sincTable[i] = isnan(y) ? 1.0 : y;
}
}