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Implemented cosine similarity correction for EFM symbols in ld-proces… #536

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merged 1 commit into from
Aug 13, 2020
Merged

Implemented cosine similarity correction for EFM symbols in ld-proces… #536

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34 changes: 32 additions & 2 deletions tools/ld-process-efm/Datatypes/f3frame.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@ F3Frame::F3Frame()
{
validEfmSymbols = 0;
invalidEfmSymbols = 0;
correctedEfmSymbols = 0;

isSync0 = false;
isSync1 = false;
Expand All @@ -50,6 +51,7 @@ F3Frame::F3Frame(uchar *tValuesIn, qint32 tLength)
{
validEfmSymbols = 0;
invalidEfmSymbols = 0;
correctedEfmSymbols = 0;

isSync0 = false;
isSync1 = false;
Expand Down Expand Up @@ -175,6 +177,12 @@ qint64 F3Frame::getNumberOfInvalidEfmSymbols()
return invalidEfmSymbols;
}

// Return the number of corrected EFM symbols in the frame
qint64 F3Frame::getNumberOfCorrectedEfmSymbols()
{
return correctedEfmSymbols;
}

// This method returns the 32 data symbols for the F3 Frame
uchar *F3Frame::getDataSymbols()
{
Expand Down Expand Up @@ -208,7 +216,7 @@ bool F3Frame::isSubcodeSync1()
// Private methods ----------------------------------------------------------------------------------------------------

// Method to translate 14-bit EFM value into 8-bit byte
// Returns -1 if the EFM value is invalid
// Returns -1 if the EFM value is could not be converted
qint16 F3Frame::translateEfm(qint16 efmValue)
{
qint16 result = -1;
Expand All @@ -218,7 +226,29 @@ qint16 F3Frame::translateEfm(qint16 efmValue)
lutPos++;
}

if (result == -1) invalidEfmSymbols++; else validEfmSymbols++;
// Was 14-bit EFM symbol invalid?
if (result == -1) {
// Symbol was invalid
invalidEfmSymbols++;

// Attempt to recover symbol using cosine similarity lookup
result = -1;
lutPos = 0;
while (result == -1 && lutPos < 16384) {
if (efmerr2positionLUT[lutPos] == efmValue) result = lutPos;
lutPos++;
}

// Was lookup successful?
if (result != -1) {
// Get the translated value from the second LUT
result = efmerr2valueLUT[result];
correctedEfmSymbols++;
}
} else {
// Symbol was valid
validEfmSymbols++;
}

return result;
}
Expand Down
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