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reverse generator order to match order of message

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This commit is contained in:
Ahmet Inan 2018-09-23 21:37:46 +02:00
commit e62dbb13c7
1 changed files with 8 additions and 8 deletions
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16
bose_chaudhuri_hocquenghem_encoder.hh
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@ -23,9 +23,9 @@ public:
{
// $generator(x) = \prod_i(minpoly_i(x))$
int generator_degree = 1;
generator[0] = 1;
for (int i = 1; i < G; ++i)
for (int i = 0; i < G; ++i)
generator[i] = 0;
set_be_bit(generator, NP, 1);
for (auto m: minimal_polynomials) {
assert(0 < m);
int m_degree = 0;
@ -34,11 +34,11 @@ public:
--m_degree;
assert(generator_degree + m_degree <= NP + 1);
for (int i = generator_degree; i >= 0; --i) {
if (!get_le_bit(generator, i))
if (!get_be_bit(generator, NP-i))
continue;
set_le_bit(generator, i, m&1);
set_be_bit(generator, NP-i, m&1);
for (int j = 1; j <= m_degree; ++j)
xor_le_bit(generator, i+j, (m>>j)&1);
xor_be_bit(generator, NP-(i+j), (m>>j)&1);
}
generator_degree += m_degree;
}
@ -46,7 +46,7 @@ public:
if (0) {
std::cerr << "generator =";
for (int i = 0; i <= NP; ++i)
std::cerr << " " << get_le_bit(generator, i);
std::cerr << " " << get_be_bit(generator, NP-i);
std::cerr << std::endl;
}
}
@ -58,8 +58,8 @@ public:
for (int i = 0; i < K; ++i) {
if (get_be_bit(code, i) != get_be_bit(code, K)) {
for (int j = 1; j < NP; ++j)
set_be_bit(code, K+j-1, get_le_bit(generator, NP-j) != get_be_bit(code, K+j));
set_be_bit(code, N-1, get_le_bit(generator, 0));
set_be_bit(code, K+j-1, get_be_bit(generator, j) != get_be_bit(code, K+j));
set_be_bit(code, N-1, get_be_bit(generator, NP));
} else {
uint8_t mask = (1<<(8-K%8))-1;
code[K/8] = (~mask&code[K/8]) | (mask&((code[K/8]<<1)|(code[K/8+1]>>7)));