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added data_len argument for shortened codes

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This commit is contained in:
Ahmet Inan 2018-09-27 18:29:13 +02:00
commit 62819a5376
4 changed files with 60 additions and 39 deletions
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48
bose_chaudhuri_hocquenghem_decoder.hh
View file

@ -34,35 +34,41 @@ private:
} }
} }
public: public:
int compute_syndromes(uint8_t *data, uint8_t *parity, ValueType *syndromes) int compute_syndromes(uint8_t *data, uint8_t *parity, ValueType *syndromes, int data_len = K)
{ {
assert(0 < data_len && data_len <= K);
// $syndromes_i = code(pe^{FCR+i})$ // $syndromes_i = code(pe^{FCR+i})$
ValueType coeff(get_be_bit(data, 0)); ValueType coeff(get_be_bit(data, 0));
for (int i = 0; i < NR; ++i) for (int i = 0; i < NR; ++i)
syndromes[i] = coeff; syndromes[i] = coeff;
update_syndromes(data, syndromes, 1, K); update_syndromes(data, syndromes, 1, data_len);
update_syndromes(parity, syndromes, 0, NP); update_syndromes(parity, syndromes, 0, NP);
int nonzero = 0; int nonzero = 0;
for (int i = 0; i < NR; ++i) for (int i = 0; i < NR; ++i)
nonzero += !!syndromes[i]; nonzero += !!syndromes[i];
return nonzero; return nonzero;
} }
int compute_syndromes(uint8_t *data, uint8_t *parity, value_type *syndromes) int compute_syndromes(uint8_t *data, uint8_t *parity, value_type *syndromes, int data_len = K)
{ {
return compute_syndromes(data, parity, reinterpret_cast<ValueType *>(syndromes)); return compute_syndromes(data, parity, reinterpret_cast<ValueType *>(syndromes), data_len);
} }
int operator()(uint8_t *data, uint8_t *parity, value_type *erasures = 0, int erasures_count = 0) int operator()(uint8_t *data, uint8_t *parity, value_type *erasures = 0, int erasures_count = 0, int data_len = K)
{ {
assert(0 <= erasures_count && erasures_count <= NR); assert(0 <= erasures_count && erasures_count <= NR);
assert(0 < data_len && data_len <= K);
if (0) { if (0) {
for (int i = 0; i < erasures_count; ++i) { for (int i = 0; i < erasures_count; ++i) {
int idx = (int)erasures[i]; int idx = (int)erasures[i];
if (idx < K) if (idx < data_len)
set_be_bit(data, idx, 0); set_be_bit(data, idx, 0);
else else
set_be_bit(parity, idx-K, 0); set_be_bit(parity, idx-data_len, 0);
} }
} }
if (erasures_count && data_len < K) {
for (int i = 0; i < erasures_count; ++i)
erasures[i] += K - data_len;
}
ValueType syndromes[NR]; ValueType syndromes[NR];
if (!compute_syndromes(data, parity, syndromes)) if (!compute_syndromes(data, parity, syndromes))
return 0; return 0;
@ -75,12 +81,12 @@ public:
if (1 < (int)magnitudes[i]) if (1 < (int)magnitudes[i])
return -1; return -1;
for (int i = 0; i < count; ++i) { for (int i = 0; i < count; ++i) {
int idx = (int)locations[i]; int idx = (int)locations[i] + data_len - K;
bool err = (bool)magnitudes[i]; bool err = (bool)magnitudes[i];
if (idx < K) if (idx < data_len)
xor_be_bit(data, idx, err); xor_be_bit(data, idx, err);
else else
xor_be_bit(parity, idx-K, err); xor_be_bit(parity, idx-data_len, err);
} }
int corrections_count = 0; int corrections_count = 0;
for (int i = 0; i < count; ++i) for (int i = 0; i < count; ++i)
@ -111,31 +117,37 @@ private:
} }
} }
public: public:
int compute_syndromes(ValueType *data, ValueType *parity, ValueType *syndromes) int compute_syndromes(ValueType *data, ValueType *parity, ValueType *syndromes, int data_len = K)
{ {
assert(0 < data_len && data_len <= K);
// $syndromes_i = code(pe^{FCR+i})$ // $syndromes_i = code(pe^{FCR+i})$
ValueType coeff(data[0]); ValueType coeff(data[0]);
for (int i = 0; i < NR; ++i) for (int i = 0; i < NR; ++i)
syndromes[i] = coeff; syndromes[i] = coeff;
update_syndromes(data, syndromes, 1, K); update_syndromes(data, syndromes, 1, data_len);
update_syndromes(parity, syndromes, 0, NP); update_syndromes(parity, syndromes, 0, NP);
int nonzero = 0; int nonzero = 0;
for (int i = 0; i < NR; ++i) for (int i = 0; i < NR; ++i)
nonzero += !!syndromes[i]; nonzero += !!syndromes[i];
return nonzero; return nonzero;
} }
int operator()(ValueType *data, ValueType *parity, IndexType *erasures = 0, int erasures_count = 0) int operator()(ValueType *data, ValueType *parity, IndexType *erasures = 0, int erasures_count = 0, int data_len = K)
{ {
assert(0 <= erasures_count && erasures_count <= NR); assert(0 <= erasures_count && erasures_count <= NR);
assert(0 < data_len && data_len <= K);
if (0) { if (0) {
for (int i = 0; i < erasures_count; ++i) { for (int i = 0; i < erasures_count; ++i) {
int idx = (int)erasures[i]; int idx = (int)erasures[i];
if (idx < K) if (idx < data_len)
data[idx] = ValueType(0); data[idx] = ValueType(0);
else else
parity[idx-K] = ValueType(0); parity[idx-data_len] = ValueType(0);
} }
} }
if (erasures_count && data_len < K) {
for (int i = 0; i < erasures_count; ++i)
erasures[i] = IndexType((int)erasures[i] + K - data_len);
}
ValueType syndromes[NR]; ValueType syndromes[NR];
if (!compute_syndromes(data, parity, syndromes)) if (!compute_syndromes(data, parity, syndromes))
return 0; return 0;
@ -148,11 +160,11 @@ public:
if (1 < (int)magnitudes[i]) if (1 < (int)magnitudes[i])
return -1; return -1;
for (int i = 0; i < count; ++i) { for (int i = 0; i < count; ++i) {
int idx = (int)locations[i]; int idx = (int)locations[i] + data_len - K;
if (idx < K) if (idx < data_len)
data[idx] += magnitudes[i]; data[idx] += magnitudes[i];
else else
parity[idx-K] += magnitudes[i]; parity[idx-data_len] += magnitudes[i];
} }
int corrections_count = 0; int corrections_count = 0;
for (int i = 0; i < count; ++i) for (int i = 0; i < count; ++i)

10
bose_chaudhuri_hocquenghem_encoder.hh
View file

@ -59,12 +59,13 @@ public:
set_be_bit(generator, i, get_be_bit(generator, i+1)); set_be_bit(generator, i, get_be_bit(generator, i+1));
set_be_bit(generator, NP, 0); set_be_bit(generator, NP, 0);
} }
void operator()(uint8_t *data, uint8_t *parity) void operator()(uint8_t *data, uint8_t *parity, int data_len = K)
{ {
assert(0 < data_len && data_len <= K);
// $code = data * x^{NP} + (data * x^{NP}) \mod{generator}$ // $code = data * x^{NP} + (data * x^{NP}) \mod{generator}$
for (int l = 0; l < NP/8; ++l) for (int l = 0; l < NP/8; ++l)
parity[l] = 0; parity[l] = 0;
for (int i = 0; i < K; ++i) { for (int i = 0; i < data_len; ++i) {
if (get_be_bit(data, i) != get_be_bit(parity, 0)) { if (get_be_bit(data, i) != get_be_bit(parity, 0)) {
for (int l = 0; l < (NP-1)/8; ++l) for (int l = 0; l < (NP-1)/8; ++l)
parity[l] = generator[l] ^ slb1(parity, l); parity[l] = generator[l] ^ slb1(parity, l);
@ -125,12 +126,13 @@ public:
std::cerr << std::endl; std::cerr << std::endl;
} }
} }
void operator()(ValueType *data, ValueType *parity) void operator()(ValueType *data, ValueType *parity, int data_len = K)
{ {
assert(0 < data_len && data_len <= K);
// $code = data * x^{NP} + (data * x^{NP}) \mod{generator}$ // $code = data * x^{NP} + (data * x^{NP}) \mod{generator}$
for (int i = 0; i < NP; ++i) for (int i = 0; i < NP; ++i)
parity[i] = ValueType(0); parity[i] = ValueType(0);
for (int i = 0; i < K; ++i) { for (int i = 0; i < data_len; ++i) {
if (data[i] != parity[0]) { if (data[i] != parity[0]) {
for (int j = 1; j < NP; ++j) for (int j = 1; j < NP; ++j)
parity[j-1] = generator[NP-j] + parity[j]; parity[j-1] = generator[NP-j] + parity[j];

32
reed_solomon_decoder.hh
View file

@ -33,33 +33,39 @@ private:
} }
} }
public: public:
int compute_syndromes(ValueType *data, ValueType *parity, ValueType *syndromes) int compute_syndromes(ValueType *data, ValueType *parity, ValueType *syndromes, int data_len = K)
{ {
assert(0 < data_len && data_len <= K);
// $syndromes_i = code(pe^{FCR+i})$ // $syndromes_i = code(pe^{FCR+i})$
ValueType coeff(data[0]); ValueType coeff(data[0]);
for (int i = 0; i < NR; ++i) for (int i = 0; i < NR; ++i)
syndromes[i] = coeff; syndromes[i] = coeff;
update_syndromes(data, syndromes, 1, K); update_syndromes(data, syndromes, 1, data_len);
update_syndromes(parity, syndromes, 0, NP); update_syndromes(parity, syndromes, 0, NP);
int nonzero = 0; int nonzero = 0;
for (int i = 0; i < NR; ++i) for (int i = 0; i < NR; ++i)
nonzero += !!syndromes[i]; nonzero += !!syndromes[i];
return nonzero; return nonzero;
} }
int operator()(ValueType *data, ValueType *parity, IndexType *erasures = 0, int erasures_count = 0) int operator()(ValueType *data, ValueType *parity, IndexType *erasures = 0, int erasures_count = 0, int data_len = K)
{ {
assert(0 <= erasures_count && erasures_count <= NR); assert(0 <= erasures_count && erasures_count <= NR);
assert(0 < data_len && data_len <= K);
if (0) { if (0) {
for (int i = 0; i < erasures_count; ++i) { for (int i = 0; i < erasures_count; ++i) {
int idx = (int)erasures[i]; int idx = (int)erasures[i];
if (idx < K) if (idx < data_len)
data[idx] = ValueType(0); data[idx] = ValueType(0);
else else
parity[idx-K] = ValueType(0); parity[idx-data_len] = ValueType(0);
} }
} }
if (erasures_count && data_len < K) {
for (int i = 0; i < erasures_count; ++i)
erasures[i] = IndexType((int)erasures[i] + K - data_len);
}
ValueType syndromes[NR]; ValueType syndromes[NR];
if (!compute_syndromes(data, parity, syndromes)) if (!compute_syndromes(data, parity, syndromes, data_len))
return 0; return 0;
IndexType locations[NR]; IndexType locations[NR];
ValueType magnitudes[NR]; ValueType magnitudes[NR];
@ -67,24 +73,24 @@ public:
if (count <= 0) if (count <= 0)
return count; return count;
for (int i = 0; i < count; ++i) { for (int i = 0; i < count; ++i) {
int idx = (int)locations[i]; int idx = (int)locations[i] + data_len - K;
if (idx < K) if (idx < data_len)
data[idx] += magnitudes[i]; data[idx] += magnitudes[i];
else else
parity[idx-K] += magnitudes[i]; parity[idx-data_len] += magnitudes[i];
} }
int corrections_count = 0; int corrections_count = 0;
for (int i = 0; i < count; ++i) for (int i = 0; i < count; ++i)
corrections_count += !!magnitudes[i]; corrections_count += !!magnitudes[i];
return corrections_count; return corrections_count;
} }
int operator()(value_type *data, value_type *parity, value_type *erasures = 0, int erasures_count = 0) int operator()(value_type *data, value_type *parity, value_type *erasures = 0, int erasures_count = 0, int data_len = K)
{ {
return (*this)(reinterpret_cast<ValueType *>(data), reinterpret_cast<ValueType *>(parity), reinterpret_cast<IndexType *>(erasures), erasures_count); return (*this)(reinterpret_cast<ValueType *>(data), reinterpret_cast<ValueType *>(parity), reinterpret_cast<IndexType *>(erasures), erasures_count, data_len);
} }
int compute_syndromes(value_type *data, value_type *parity, value_type *syndromes) int compute_syndromes(value_type *data, value_type *parity, value_type *syndromes, int data_len = K)
{ {
return compute_syndromes(reinterpret_cast<ValueType *>(data), reinterpret_cast<ValueType *>(parity), reinterpret_cast<ValueType *>(syndromes)); return compute_syndromes(reinterpret_cast<ValueType *>(data), reinterpret_cast<ValueType *>(parity), reinterpret_cast<ValueType *>(syndromes), data_len);
} }
}; };

9
reed_solomon_encoder.hh
View file

@ -48,12 +48,13 @@ public:
for (int i = 0; i <= NR; ++i) for (int i = 0; i <= NR; ++i)
generator[i] = index(tmp[i]); generator[i] = index(tmp[i]);
} }
void operator()(ValueType *data, ValueType *parity) void operator()(ValueType *data, ValueType *parity, int data_len = K)
{ {
assert(0 < data_len && data_len <= K);
// $code = data * x^{NR} + (data * x^{NR}) \mod{generator}$ // $code = data * x^{NR} + (data * x^{NR}) \mod{generator}$
for (int i = 0; i < NR; ++i) for (int i = 0; i < NR; ++i)
parity[i] = ValueType(0); parity[i] = ValueType(0);
for (int i = 0; i < K; ++i) { for (int i = 0; i < data_len; ++i) {
ValueType feedback = data[i] + parity[0]; ValueType feedback = data[i] + parity[0];
if (feedback) { if (feedback) {
IndexType fb = index(feedback); IndexType fb = index(feedback);
@ -67,9 +68,9 @@ public:
} }
} }
} }
void operator()(value_type *data, value_type *parity) void operator()(value_type *data, value_type *parity, int data_len = K)
{ {
(*this)(reinterpret_cast<ValueType *>(data), reinterpret_cast<ValueType *>(parity)); (*this)(reinterpret_cast<ValueType *>(data), reinterpret_cast<ValueType *>(parity), data_len);
} }
}; };