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Stop generating DVD ecc and replace with null bytes #402

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Merged
superg merged 1 commit into from
Jul 5, 2026
+0 −36
Merged

Stop generating DVD ecc and replace with null bytes #402

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36 changes: 0 additions & 36 deletions dvd/dvd.ixx
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Original file line number Diff line number Diff line change
Expand Up @@ -121,37 +121,6 @@ export struct RecordingFrame
};


void compute_parity_inner(std::span<uint8_t> parity_inner, std::span<const uint8_t> main_data)
{
// PI: RS(n,k,d) where n=data_size+parity_size, k=data_size, d=parity_size
// generator polynomial roots: alpha^0, alpha^1, ..., alpha^(parity_size-1)
uint8_t parity[ECC_FRAMES] = {};
for(uint32_t col = 0; col < main_data.size(); ++col)
{
uint8_t feedback = gf.add(main_data[col], parity[0]);
for(uint32_t j = 0; j < parity_inner.size() - 1; ++j)
parity[j] = gf.add(parity[j + 1], gf.mul(feedback, gf.exp[parity_inner.size() - 1 - j]));
parity[parity_inner.size() - 1] = gf.mul(feedback, gf.exp[0]);
}
for(uint32_t j = 0; j < parity_inner.size(); ++j)
parity_inner[j] = parity[parity_inner.size() - 1 - j];
}


void compute_parity_outer(std::span<uint8_t> parity_outer, std::span<const uint8_t> main_data, uint32_t stride)
{
// PO: simplified single-frame encoding
// treat each column as data_size bytes and compute 1 parity byte
for(uint32_t col = 0; col < parity_outer.size(); ++col)
{
uint8_t parity = 0;
for(uint32_t row = 0; row < main_data.size() / stride; ++row)
parity = gf.add(parity, main_data[row * stride + col]);
parity_outer[col] = parity;
}
}


export RecordingFrame DataFrame_to_RecordingFrame(const DataFrame &data_frame)
{
RecordingFrame recording_frame = {};
Expand All @@ -161,11 +130,6 @@ export RecordingFrame DataFrame_to_RecordingFrame(const DataFrame &data_frame)
for(uint32_t i = 0; i < std::size(recording_frame.row); ++i)
std::copy_n(src + i * std::size(recording_frame.row[i].main_data), std::size(recording_frame.row[i].main_data), recording_frame.row[i].main_data);

for(uint32_t i = 0; i < std::size(recording_frame.row); ++i)
compute_parity_inner(recording_frame.row[i].parity_inner, recording_frame.row[i].main_data);

compute_parity_outer(recording_frame.parity_outer, std::span((uint8_t *)recording_frame.row, sizeof(recording_frame.row)), sizeof(recording_frame.row[0]));

return recording_frame;
}

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