aboutsummaryrefslogtreecommitdiffstats
path: root/CommonLibs/BitVector.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'CommonLibs/BitVector.cpp')
-rw-r--r--CommonLibs/BitVector.cpp241
1 files changed, 0 insertions, 241 deletions
diff --git a/CommonLibs/BitVector.cpp b/CommonLibs/BitVector.cpp
index 8389237..b77a4c4 100644
--- a/CommonLibs/BitVector.cpp
+++ b/CommonLibs/BitVector.cpp
@@ -217,30 +217,6 @@ uint64_t BitVector::parity(Generator& gen) const
}
-void BitVector::encode(const ViterbiR2O4& coder, BitVector& target)
-{
- size_t sz = size();
- assert(sz*coder.iRate() == target.size());
-
- // Build a "history" array where each element contains the full history.
- uint32_t history[sz];
- uint32_t accum = 0;
- for (size_t i=0; i<sz; i++) {
- accum = (accum<<1) | bit(i);
- history[i] = accum;
- }
-
- // Look up histories in the pre-generated state table.
- char *op = target.begin();
- for (size_t i=0; i<sz; i++) {
- unsigned index = coder.cMask() & history[i];
- for (unsigned g=0; g<coder.iRate(); g++) {
- *op++ = coder.stateTable(g,index);
- }
- }
-}
-
-
unsigned BitVector::sum() const
{
@@ -287,142 +263,6 @@ ostream& operator<<(ostream& os, const BitVector& hv)
-ViterbiR2O4::ViterbiR2O4()
-{
- assert(mDeferral < 32);
- mCoeffs[0] = 0x019;
- mCoeffs[1] = 0x01b;
- computeStateTables(0);
- computeStateTables(1);
- computeGeneratorTable();
-}
-
-
-
-
-void ViterbiR2O4::initializeStates()
-{
- for (unsigned i=0; i<mIStates; i++) clear(mSurvivors[i]);
- for (unsigned i=0; i<mNumCands; i++) clear(mCandidates[i]);
-}
-
-
-
-void ViterbiR2O4::computeStateTables(unsigned g)
-{
- assert(g<mIRate);
- for (unsigned state=0; state<mIStates; state++) {
- // 0 input
- uint32_t inputVal = state<<1;
- mStateTable[g][inputVal] = applyPoly(inputVal, mCoeffs[g], mOrder+1);
- // 1 input
- inputVal |= 1;
- mStateTable[g][inputVal] = applyPoly(inputVal, mCoeffs[g], mOrder+1);
- }
-}
-
-void ViterbiR2O4::computeGeneratorTable()
-{
- for (unsigned index=0; index<mIStates*2; index++) {
- mGeneratorTable[index] = (mStateTable[0][index]<<1) | mStateTable[1][index];
- }
-}
-
-
-
-
-
-
-void ViterbiR2O4::branchCandidates()
-{
- // Branch to generate new input states.
- const vCand *sp = mSurvivors;
- for (unsigned i=0; i<mNumCands; i+=2) {
- // extend and suffix
- const uint32_t iState0 = (sp->iState) << 1; // input state for 0
- const uint32_t iState1 = iState0 | 0x01; // input state for 1
- const uint32_t oStateShifted = (sp->oState) << mIRate; // shifted output
- const float cost = sp->cost;
- sp++;
- // 0 input extension
- mCandidates[i].cost = cost;
- mCandidates[i].oState = oStateShifted | mGeneratorTable[iState0 & mCMask];
- mCandidates[i].iState = iState0;
- // 1 input extension
- mCandidates[i+1].cost = cost;
- mCandidates[i+1].oState = oStateShifted | mGeneratorTable[iState1 & mCMask];
- mCandidates[i+1].iState = iState1;
- }
-}
-
-
-void ViterbiR2O4::getSoftCostMetrics(const uint32_t inSample, const float *matchCost, const float *mismatchCost)
-{
- const float *cTab[2] = {matchCost,mismatchCost};
- for (unsigned i=0; i<mNumCands; i++) {
- vCand& thisCand = mCandidates[i];
- // We examine input bits 2 at a time for a rate 1/2 coder.
- const unsigned mismatched = inSample ^ (thisCand.oState);
- thisCand.cost += cTab[mismatched&0x01][1] + cTab[(mismatched>>1)&0x01][0];
- }
-}
-
-
-void ViterbiR2O4::pruneCandidates()
-{
- const vCand* c1 = mCandidates; // 0-prefix
- const vCand* c2 = mCandidates + mIStates; // 1-prefix
- for (unsigned i=0; i<mIStates; i++) {
- if (c1[i].cost < c2[i].cost) mSurvivors[i] = c1[i];
- else mSurvivors[i] = c2[i];
- }
-}
-
-
-const ViterbiR2O4::vCand& ViterbiR2O4::minCost() const
-{
- int minIndex = 0;
- float minCost = mSurvivors[0].cost;
- for (unsigned i=1; i<mIStates; i++) {
- const float thisCost = mSurvivors[i].cost;
- if (thisCost>=minCost) continue;
- minCost = thisCost;
- minIndex=i;
- }
- return mSurvivors[minIndex];
-}
-
-
-const ViterbiR2O4::vCand& ViterbiR2O4::step(uint32_t inSample, const float *probs, const float *iprobs)
-{
- branchCandidates();
- getSoftCostMetrics(inSample,probs,iprobs);
- pruneCandidates();
- return minCost();
-}
-
-
-uint64_t Parity::syndrome(const BitVector& receivedCodeword)
-{
- return receivedCodeword.syndrome(*this);
-}
-
-
-void Parity::writeParityWord(const BitVector& data, BitVector& parityTarget, bool invert)
-{
- uint64_t pWord = data.parity(*this);
- if (invert) pWord = ~pWord;
- parityTarget.fillField(0,pWord,size());
-}
-
-
-
-
-
-
-
-
-
SoftVector::SoftVector(const BitVector& source)
{
resize(source.size());
@@ -445,87 +285,6 @@ BitVector SoftVector::sliced() const
}
-
-void SoftVector::decode(ViterbiR2O4 &decoder, BitVector& target) const
-{
- const size_t sz = size();
- const unsigned deferral = decoder.deferral();
- const size_t ctsz = sz + deferral*decoder.iRate();
- assert(sz <= decoder.iRate()*target.size());
-
- // Build a "history" array where each element contains the full history.
- uint32_t history[ctsz];
- {
- BitVector bits = sliced();
- uint32_t accum = 0;
- for (size_t i=0; i<sz; i++) {
- accum = (accum<<1) | bits.bit(i);
- history[i] = accum;
- }
- // Repeat last bit at the end.
- for (size_t i=sz; i<ctsz; i++) {
- accum = (accum<<1) | (accum & 0x01);
- history[i] = accum;
- }
- }
-
- // Precompute metric tables.
- float matchCostTable[ctsz];
- float mismatchCostTable[ctsz];
- {
- const float *dp = mStart;
- for (size_t i=0; i<sz; i++) {
- // pVal is the probability that a bit is correct.
- // ipVal is the probability that a bit is incorrect.
- float pVal = dp[i];
- if (pVal>0.5F) pVal = 1.0F-pVal;
- float ipVal = 1.0F-pVal;
- // This is a cheap approximation to an ideal cost function.
- if (pVal<0.01F) pVal = 0.01;
- if (ipVal<0.01F) ipVal = 0.01;
- matchCostTable[i] = 0.25F/ipVal;
- mismatchCostTable[i] = 0.25F/pVal;
- }
-
- // pad end of table with unknowns
- for (size_t i=sz; i<ctsz; i++) {
- matchCostTable[i] = 0.5F;
- mismatchCostTable[i] = 0.5F;
- }
- }
-
- {
- decoder.initializeStates();
- // Each sample of history[] carries its history.
- // So we only have to process every iRate-th sample.
- const unsigned step = decoder.iRate();
- // input pointer
- const uint32_t *ip = history + step - 1;
- // output pointers
- char *op = target.begin();
- const char *const opt = target.end();
- // table pointers
- const float* match = matchCostTable;
- const float* mismatch = mismatchCostTable;
- size_t oCount = 0;
- while (op<opt) {
- // Viterbi algorithm
- assert(match-matchCostTable<sizeof(matchCostTable)/sizeof(matchCostTable[0])-1);
- assert(mismatch-mismatchCostTable<sizeof(mismatchCostTable)/sizeof(mismatchCostTable[0])-1);
- const ViterbiR2O4::vCand &minCost = decoder.step(*ip, match, mismatch);
- ip += step;
- match += step;
- mismatch += step;
- // output
- if (oCount>=deferral) *op++ = (minCost.iState >> deferral)&0x01;
- oCount++;
- }
- }
-}
-
-
-
-// (pat) Added 6-22-2012
float SoftVector::getEnergy(float *plow) const
{
const SoftVector &vec = *this;
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-08 20:36:25 +0000