void RaptorQ__v1::Impl::Operation_Reorder::build_mtx (
RaptorQ__v1::Impl::DenseMtx &mtx) const
{
uint16_t overhead = static_cast<uint16_t> (
static_cast<uint16_t> (mtx.rows()) - _order.size());
DenseMtx ret = DenseMtx (mtx.rows() - overhead , mtx.cols());
// reorder some of the lines as requested by the _order vector
uint16_t row = 0;
for (const uint16_t pos : _order)
ret.row (pos) = mtx.row (row++);
mtx = ret;
// other lines will not influence the computation, ignore them
}
void Precode_Matrix::gen (const uint32_t repair_overhead)
{
_repair_overhead = repair_overhead;
A = DenseMtx (_params.L + repair_overhead, _params.L);
init_LDPC1 (_params.S, _params.B);
add_identity (_params.S, 0, _params.B);
init_LDPC2 (_params.W, _params.S, _params.P);
init_HDPC ();
add_identity (_params.H, _params.S, _params.L - _params.H);
add_G_ENC ();
// G_ENC only fills up to L rows, but we might have overhead.
// initialize it.
for (uint16_t row = _params.L; row < A.rows(); ++row) {
for (uint16_t col = 0; col < A.cols(); ++col)
A(row, col) = 0;
}
}
DenseMtx Precode_Matrix::make_GAMMA() const
{
// rfc 6330, pg 24
DenseMtx GAMMA = DenseMtx (_params.K_padded + _params.S,
_params.K_padded + _params.S);
for (uint16_t row = 0; row < GAMMA.rows(); ++row) {
uint16_t col;
for (col = 0; col <= row; ++col)
// alpha ^^ (i-j), as in rfc6330, pg24
// rfc only says "i-j", but we could go well over oct_exp size.
// we hope they just missed a modulus :/
GAMMA (row, col) = RaptorQ::Impl::oct_exp[(row - col) %
RaptorQ::Impl::oct_exp.size()];
for (; col < GAMMA.cols(); ++col) {
GAMMA (row, col) = 0;
}
}
return GAMMA;
}
DenseMtx Precode_Matrix::make_MT() const
{
// rfc 6330, pg 24
Rand rnd;
DenseMtx MT = DenseMtx (_params.H, _params.K_padded + _params.S);
for (uint16_t row = 0; row < MT.rows(); ++row) {
uint16_t col;
for (col = 0; col < MT.cols() - 1; ++col) {
auto tmp = rnd.get (col + 1, 6, _params.H);
if ((row == tmp) || (row ==
(tmp + rnd.get (col + 1, 7, _params.H - 1) + 1)
% _params.H)) {
MT (row, col) = 1;
} else {
MT (row, col) = 0;
}
}
// last column: alpha ^^ i, as in rfc6330
MT (row, col) = RaptorQ::Impl::oct_exp[row];
}
return MT;
}
