forked from osherbakov/MELPeModem
/
EncodeDecode.cs
534 lines (472 loc) · 16.9 KB
/
EncodeDecode.cs
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using System;
using System.Collections.Generic;
using System.Text;
namespace MELPeModem
{
[Flags]
public enum EncodingType
{
NON_DIFF = 0x00,
DIFF = 0x01,
DIFF_ADD = 0x01,
DIFF_SUB = 0x03,
DIFF_XOR = 0x05,
DIFF_XNOR = 0x07,
DIFF_MASK = 0x07,
SCRAMBLE = 0x010,
SCRAMBLE_ADD = 0x010,
SCRAMBLE_SUB = 0x030,
SCRAMBLE_XOR = 0x050,
SCRAMBLE_XNOR = 0x070,
SCRAMBLE_MASK = 0x070,
SAVE_IN1 = 0x0100,
SAVE_IN2 = 0x0300,
SAVE_OUT1 = 0x0500,
SAVE_OUT2 = 0x0700,
SAVE_MASK = 0x0700,
DIFF_IQ = 0x8000
}
class IQEncoder
{
int BitsPerSymbol;
int MaxSymbols;
int SymbolMask;
int[] BitsToSymbol;
IQ[] SymbolToIQ;
EncodingType EncType;
int PrevSymbol;
IQ PrevIQ;
public IQEncoder(int bitsPerSymb, int[] tableBitsToSymb, IQ[] tableSymbToIQ, EncodingType mType)
{
BitsPerSymbol = bitsPerSymb;
MaxSymbols = 1 << bitsPerSymb;
SymbolMask = MaxSymbols - 1;
BitsToSymbol = new int[tableBitsToSymb.Length];
tableBitsToSymb.CopyTo(BitsToSymbol, 0);
SymbolToIQ = new IQ[tableSymbToIQ.Length];
tableSymbToIQ.CopyTo(SymbolToIQ, 0);
EncType = mType;
Init();
}
public IQEncoder(int bitsPerSymb, int[] tableBitsToSymb,
float[] tableSymbToI, float[] tableSymbToQ, EncodingType mType)
{
BitsPerSymbol = bitsPerSymb;
MaxSymbols = 1 << bitsPerSymb;
SymbolMask = MaxSymbols - 1;
BitsToSymbol = new int[tableBitsToSymb.Length];
tableBitsToSymb.CopyTo(BitsToSymbol, 0);
SymbolToIQ = new IQ[tableSymbToI.Length];
for (int i = 0; i < tableSymbToI.Length; i++)
{
SymbolToIQ[i] = new IQ(tableSymbToI[i], tableSymbToQ[i]);
}
EncType = mType;
Init();
}
public void Init()
{
PrevSymbol = 0;
PrevIQ = IQ.UNITY;
}
int ProcessIn(int inBits)
{
int newSymbol = BitsToSymbol[inBits & SymbolMask];
int OutSymbol = newSymbol;
if ((EncType & EncodingType.DIFF) != 0)
{
switch (EncType & EncodingType.DIFF_MASK)
{
case EncodingType.DIFF_ADD:
OutSymbol += PrevSymbol;
break;
case EncodingType.DIFF_SUB:
OutSymbol -= PrevSymbol;
break;
case EncodingType.DIFF_XOR:
OutSymbol ^= PrevSymbol;
break;
case EncodingType.DIFF_XNOR:
OutSymbol ^= ~PrevSymbol;
break;
}
switch (EncType & EncodingType.SAVE_MASK)
{
case EncodingType.SAVE_IN1:
PrevSymbol = inBits;
break;
case EncodingType.SAVE_IN2:
PrevSymbol = newSymbol;
break;
case EncodingType.SAVE_OUT1:
PrevSymbol = OutSymbol;
break;
case EncodingType.SAVE_OUT2:
PrevSymbol = OutSymbol;
break;
}
OutSymbol &= SymbolMask;
}
return OutSymbol;
}
int ProcessScramble(int inBits, int scrambleSymbol, int scrambleMask)
{
int newSymbol = inBits;
if ((EncType & EncodingType.SCRAMBLE) != 0)
{
switch (EncType & EncodingType.SCRAMBLE_MASK)
{
case EncodingType.SCRAMBLE_ADD:
newSymbol += scrambleSymbol;
break;
case EncodingType.SCRAMBLE_SUB:
newSymbol -= scrambleSymbol;
break;
case EncodingType.SCRAMBLE_XOR:
newSymbol ^= scrambleSymbol;
break;
case EncodingType.SCRAMBLE_XNOR:
newSymbol ^= ~scrambleSymbol;
break;
}
if ((EncType & EncodingType.SAVE_MASK) == EncodingType.SAVE_OUT2) PrevSymbol = newSymbol;
newSymbol &= scrambleMask;
}
return newSymbol;
}
public void Process(int inputBits, out IQ data)
{
int newSymbol = ProcessIn(inputBits);
data = SymbolToIQ[newSymbol];
if ( (EncType & EncodingType.DIFF_IQ) != 0)
{
data = PrevIQ * data;
PrevIQ = data;
}
}
public void Process(int inputBits, int scrambleSymbol, int scrambleMask, out IQ data)
{
int newSymbol = ProcessIn(inputBits);
newSymbol = ProcessScramble(newSymbol, scrambleSymbol, scrambleMask);
data = SymbolToIQ[newSymbol];
if ((EncType & EncodingType.DIFF_IQ) != 0)
{
data = PrevIQ * data;
PrevIQ = data;
}
}
public int PreviousSymbol
{
get { return PrevSymbol; }
set { PrevSymbol = value; }
}
public IQ PreviousIQ
{
get { return PrevIQ; }
set { PrevIQ = value; }
}
}
class IQDecoder
{
int BitsPerSymbol;
int[] BitsToSymbol;
IQ[] SymbolToIQ;
int MaxSymbols;
int SymbolMask;
EncodingType EncType;
int PrevSymbol;
IQ PrevIQ;
IQ TargetSymbol;
IQ Rotate = IQ.UNITY;
IQ FreqCorr = IQ.UNITY;
IQ PrevRotate = IQ.UNITY;
float Energy = 0;
int SymbolsToProcess;
int CurrentSymbolCnt;
float Coeff1; // (1 - 1/N);
float Coeff2; // 1/N;
public IQDecoder(int bitsPerSymb, int[] tableBitsToSymb, IQ[] tableSymbToIQ, EncodingType mType)
{
BitsPerSymbol = bitsPerSymb;
MaxSymbols = 1 << bitsPerSymb;
SymbolMask = MaxSymbols - 1;
BitsToSymbol = new int[tableBitsToSymb.Length];
tableBitsToSymb.CopyTo(BitsToSymbol, 0);
SymbolToIQ = new IQ[tableSymbToIQ.Length];
tableSymbToIQ.CopyTo(SymbolToIQ, 0);
EncType = mType;
Init();
}
public IQDecoder(int bitsPerSymb, int[] tableBitsToSymb, float[] tableSymbToI, float[] tableSymbToQ, EncodingType mType)
{
BitsPerSymbol = bitsPerSymb;
MaxSymbols = 1 << bitsPerSymb;
SymbolMask = MaxSymbols - 1;
BitsToSymbol = new int[tableBitsToSymb.Length];
tableBitsToSymb.CopyTo(BitsToSymbol, 0);
SymbolToIQ = new IQ[tableSymbToI.Length];
for (int i = 0; i < tableSymbToI.Length; i++)
{
SymbolToIQ[i] = new IQ(tableSymbToI[i], tableSymbToQ[i]);
}
EncType = mType;
Init();
}
public void Init()
{
PrevSymbol = 0;
PrevIQ = IQ.UNITY;
SymbolsToProcess = CurrentSymbolCnt = 0;
Rotate = IQ.UNITY;
FreqCorr = IQ.UNITY;
PrevRotate = IQ.UNITY;
Energy = 0;
}
public void StartCorrectionProcess(int numberOfSymbols)
{
SymbolsToProcess = numberOfSymbols;
CurrentSymbolCnt = 0;
Rotate = IQ.UNITY;
FreqCorr = IQ.UNITY;
PrevRotate = IQ.UNITY;
Energy = 0;
if (SymbolsToProcess < 0) // This is a continious mode
{
Coeff2 = -1.0f / (float)SymbolsToProcess;
Coeff1 = 1 - Coeff2;
}
}
public bool IsCorrectionReady
{
get { return (CurrentSymbolCnt >= SymbolsToProcess); }
}
int ProcessIn(int inBits)
{
int newSymbol = BitsToSymbol[inBits];
int OutSymbol = newSymbol;
if ((EncType & EncodingType.DIFF) != 0)
{
switch (EncType & EncodingType.DIFF_MASK)
{
case EncodingType.DIFF_ADD:
OutSymbol += PrevSymbol;
break;
case EncodingType.DIFF_SUB:
OutSymbol -= PrevSymbol;
break;
case EncodingType.DIFF_XOR:
OutSymbol ^= PrevSymbol;
break;
case EncodingType.DIFF_XNOR:
OutSymbol ^= ~PrevSymbol;
break;
}
OutSymbol &= SymbolMask;
}
return OutSymbol;
}
int ProcessScramble(int inBits, int scrambleSymbol, int scrambleMask)
{
int newSymbol = inBits;
if ((EncType & EncodingType.SCRAMBLE) != 0)
{
switch (EncType & EncodingType.SCRAMBLE_MASK)
{
case EncodingType.SCRAMBLE_ADD:
newSymbol += scrambleSymbol;
break;
case EncodingType.SCRAMBLE_SUB:
newSymbol -= scrambleSymbol;
break;
case EncodingType.SCRAMBLE_XOR:
newSymbol ^= scrambleSymbol;
break;
case EncodingType.SCRAMBLE_XNOR:
newSymbol ^= ~scrambleSymbol;
break;
}
newSymbol &= scrambleMask;
}
return newSymbol;
}
int ProcessDiff( int inBits)
{
int newSymbol = BitsToSymbol[inBits];
int OutSymbol = newSymbol;
if ((EncType & EncodingType.DIFF) != 0)
{
switch (EncType & EncodingType.DIFF_MASK)
{
case EncodingType.DIFF_ADD:
OutSymbol += PrevSymbol;
break;
case EncodingType.DIFF_SUB:
OutSymbol -= PrevSymbol;
break;
case EncodingType.DIFF_XOR:
OutSymbol ^= PrevSymbol;
break;
case EncodingType.DIFF_XNOR:
OutSymbol ^= ~PrevSymbol;
break;
}
OutSymbol &= SymbolMask;
switch (EncType & EncodingType.SAVE_MASK)
{
case EncodingType.SAVE_IN1:
PrevSymbol = inBits;
break;
case EncodingType.SAVE_IN2:
PrevSymbol = newSymbol;
break;
case EncodingType.SAVE_OUT1:
PrevSymbol = OutSymbol;
break;
case EncodingType.SAVE_OUT2:
PrevSymbol = OutSymbol;
break;
}
}
return OutSymbol;
}
int ProcessDiff(int inBits, int scrambleSymbol, int scrambleMask)
{
int newSymbol = ProcessDiff(inBits);
if ((EncType & EncodingType.SCRAMBLE) != 0)
{
switch (EncType & EncodingType.SCRAMBLE_MASK)
{
case EncodingType.SCRAMBLE_ADD:
newSymbol += scrambleSymbol;
break;
case EncodingType.SCRAMBLE_SUB:
newSymbol -= scrambleSymbol;
break;
case EncodingType.SCRAMBLE_XOR:
newSymbol ^= scrambleSymbol;
break;
case EncodingType.SCRAMBLE_XNOR:
newSymbol ^= ~scrambleSymbol;
break;
}
if ((EncType & EncodingType.SAVE_MASK) == EncodingType.SAVE_OUT2) PrevSymbol = newSymbol;
newSymbol &= scrambleMask;
}
return newSymbol;
}
void CalculateCorrections(IQ inputData)
{
IQ AngleError = (TargetSymbol / inputData);
if (SymbolsToProcess < 0) // Continious mode
{
Energy = Energy * Coeff1 + inputData.R2 * Coeff2;
Rotate = Rotate * Coeff1 + AngleError * Coeff2;
FreqCorr = FreqCorr * Coeff1 + (AngleError / PrevRotate) * Coeff2;
}else if (CurrentSymbolCnt < SymbolsToProcess)
{
Energy += inputData.R2;
Rotate += AngleError;
FreqCorr += AngleError / PrevRotate;
CurrentSymbolCnt++;
}
PrevRotate = AngleError;
}
public void Process(IQ inputData, out int outputSymbol)
{
float MinDistance = float.MaxValue;
int resultSymbol = 0;
IQ Data;
if ((EncType & EncodingType.DIFF_IQ) != 0)
{
Data = inputData / PrevIQ;
PrevIQ = inputData;
}
else
{
Data = inputData;
}
// Simply go thru every point in constellation and find the best match
for (int currSymbol = 0; currSymbol < MaxSymbols; currSymbol++)
{
int newSymbol = ProcessIn(currSymbol);
IQ targetData = SymbolToIQ[newSymbol];
float Distance = (targetData - Data).R2;
if (Distance < MinDistance)
{
MinDistance = Distance;
resultSymbol = currSymbol;
TargetSymbol = targetData;
}
}
ProcessDiff(resultSymbol);
CalculateCorrections(Data);
outputSymbol = resultSymbol;
}
public void Process(IQ inputData, int scrambleSymbol, int scrambleMask, out int outputSymbol)
{
float MinDistance = float.MaxValue;
int resultSymbol = 0;
IQ Data;
if ((EncType & EncodingType.DIFF_IQ) != 0)
{
Data = inputData / PrevIQ;
PrevIQ = inputData;
}
else
{
Data = inputData;
}
// Simply go thru every point in constellation and find the best match
for (int currSymbol = 0; currSymbol < MaxSymbols; currSymbol++)
{
int newSymbol = ProcessIn(currSymbol);
newSymbol = ProcessScramble(newSymbol, scrambleSymbol, scrambleMask);
IQ TargetData = SymbolToIQ[newSymbol];
float Distance = (TargetData - Data).R2;
if (Distance < MinDistance)
{
MinDistance = Distance;
resultSymbol = currSymbol;
TargetSymbol = TargetData;
}
}
ProcessDiff(resultSymbol, scrambleSymbol, scrambleMask);
CalculateCorrections(Data);
outputSymbol = resultSymbol;
}
/// <summary>
/// Correction (Rotation) factor for the IQ data.
/// </summary>
public IQ RotateCorrection
{
get
{
return Energy == 0 ? IQ.UNITY : this.Rotate / Energy;
}
}
/// <summary>
/// Correction (Frequency) factor for the IQ data.
/// </summary>
public IQ FrequencyCorrection
{
get
{
return this.FreqCorr;
}
}
public IQ Target
{
get { return TargetSymbol; }
}
public int PreviousSymbol
{
get { return PrevSymbol; }
set { PrevSymbol = value; }
}
public IQ PreviousIQ
{
get { return PrevIQ; }
set { PrevIQ = value; }
}
}
}