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zero out parity bits bytewise

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This commit is contained in:
Ahmet Inan 2018-09-23 21:40:56 +02:00
commit c90e9a6a23
1 changed files with 4 additions and 3 deletions
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7
bose_chaudhuri_hocquenghem_encoder.hh
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@ -53,15 +53,16 @@ public:
void operator()(uint8_t *code)
{
// $code = data * x^{NP} + (data * x^{NP}) \mod{generator}$
for (int i = 0; i < NP; ++i)
set_be_bit(code, K+i, 0);
static const uint8_t mask = (1<<(8-K%8))-1;
code[K/8] &= ~mask;
for (int l = K/8+1; l < N/8; ++l)
code[l] = 0;
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_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)));
for (int l = K/8+1; l < (N-1)/8; ++l)
code[l] = (code[l]<<1) | (code[l+1]>>7);