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only need first q entries

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This commit is contained in:
Ahmet Inan 2018-12-15 15:05:19 +01:00
commit 4e39392acf
1 changed files with 22 additions and 14 deletions
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36
ldpc_decoder.hh
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@ -32,8 +32,8 @@ class LDPCDecoder
TYPE bnl[BNL];
int8_t pty[R];
uint16_t pos[R * CNC];
uint8_t cnc[R];
uint16_t pos[q * CNC];
uint8_t cnc[q];
static TYPE eor(TYPE a, TYPE b)
{
@ -78,6 +78,11 @@ class LDPCDecoder
{
for (int i = 0; i < q; ++i) {
int cnt = cnc[i];
int offset[cnt], shift[cnt];
for (int c = 0; c < cnt; ++c) {
shift[c] = pos[CNC*i+c] % M;
offset[c] = pos[CNC*i+c] - shift[c];
}
auto res = vmask(vzero<TYPE>());
for (int j = 0; j < M; j += SIMD_SIZE) {
int num = std::min(M - j, SIMD_SIZE);
@ -98,7 +103,7 @@ class LDPCDecoder
TYPE dat[cnt];
for (int c = 0; c < cnt; ++c)
for (int n = 0; n < num; ++n)
dat[c].v[n] = data[pos[CNC*(M*i+j+n)+c]];
dat[c].v[n] = data[offset[c]+(shift[c]+n)%M];
TYPE cnv = vdup<TYPE>(1);
for (int c = 0; c < 2; ++c)
cnv = vsign(cnv, par[c]);
@ -107,6 +112,8 @@ class LDPCDecoder
for (int n = num; n < SIMD_SIZE; ++n)
cnv.v[n] = 1;
res = vorr(res, vclez(cnv));
for (int c = 0; c < cnt; ++c)
shift[c] = (shift[c] + num) % M;
}
for (int n = 0; n < SIMD_SIZE; ++n)
if (res.v[n])
@ -119,6 +126,11 @@ class LDPCDecoder
TYPE *bl = bnl;
for (int i = 0; i < q; ++i) {
int cnt = cnc[i];
int offset[cnt], shift[cnt];
for (int c = 0; c < cnt; ++c) {
shift[c] = pos[CNC*i+c] % M;
offset[c] = pos[CNC*i+c] - shift[c];
}
int deg = cnt + 2;
for (int j = 0; j < M; j += SIMD_SIZE) {
int num = std::min(M - j, SIMD_SIZE);
@ -139,7 +151,7 @@ class LDPCDecoder
TYPE dat[cnt];
for (int c = 0; c < cnt; ++c)
for (int n = 0; n < num; ++n)
dat[c].v[n] = data[pos[CNC*(M*i+j+n)+c]];
dat[c].v[n] = data[offset[c]+(shift[c]+n)%M];
TYPE inp[deg], out[deg];
for (int c = 0; c < cnt; ++c)
inp[c] = out[c] = vqsub(dat[c], bl[c]);
@ -166,7 +178,9 @@ class LDPCDecoder
parity[M*i+j+n] = par[1].v[n];
for (int c = 0; c < cnt; ++c)
for (int n = 0; n < num; ++n)
data[pos[CNC*(M*i+j+n)+c]] = dat[c].v[n];
data[offset[c]+(shift[c]+n)%M] = dat[c].v[n];
for (int c = 0; c < cnt; ++c)
shift[c] = (shift[c] + num) % M;
}
}
//assert(bl <= bnl + BNL);
@ -175,7 +189,7 @@ class LDPCDecoder
public:
LDPCDecoder()
{
for (int i = 0; i < R; ++i)
for (int i = 0; i < q; ++i)
cnc[i] = 0;
int bit_pos = 0;
const int *row_ptr = TABLE::POS;
@ -189,7 +203,8 @@ public:
for (int j = 0; j < M; ++j) {
for (int d = 0; d < bit_deg; ++d) {
int n = acc_pos[d];
pos[CNC*n+cnc[n]++] = bit_pos;
if (n < q)
pos[CNC*n+cnc[n]++] = bit_pos;
}
++bit_pos;
for (int d = 0; d < bit_deg; ++d)
@ -197,13 +212,6 @@ public:
}
}
}
uint16_t tmp[R * CNC];
for (int i = 0; i < q; ++i)
for (int j = 0; j < M; ++j)
for (int c = 0; c < CNC; ++c)
tmp[CNC*(M*i+j)+c] = pos[CNC*(q*j+i)+c];
for (int i = 0; i < R * CNC; ++i)
pos[i] = tmp[i];
}
int operator()(int8_t *data, int8_t *parity, int trials = 25)
{