fp.writeData(f.getPosition() - prevPos);
prevPos = f.getPosition();
switch (f.getOperator()) {
case ReadBase.operator:
ReadBase rb = (ReadBase) f;
bc.writeData(rb.getBase());
qc.writeData(rb.getQualityScore());
break;
case Substitution.operator:
Substitution sv = (Substitution) f;
if (sv.getCode() < 0)
bsc.writeData(substitutionMatrix.code(