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use uint32_t for the frozen bits

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This commit is contained in:
Ahmet Inan 2021-07-12 19:11:15 +02:00
commit 631ec8beef
6 changed files with 312 additions and 44 deletions
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33
polar_freezer.hh
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@ -12,23 +12,32 @@ namespace CODE {
class PolarFreezer
{
static void freeze(uint8_t *bits, long double pe, long double th, int i, int h)
static bool get_bit(const uint32_t *bits, int idx)
{
return (bits[idx/32] >> (idx%32)) & 1;
}
static void set_bit(uint32_t *bits, int idx, bool val)
{
bits[idx/32] &= ~(1 << (idx%32));
bits[idx/32] |= (uint32_t)val << (idx%32);
}
static void freeze(uint32_t *bits, long double pe, long double th, int i, int h)
{
if (h) {
freeze(bits, pe * (2-pe), th, i, h/2);
freeze(bits, pe * pe, th, i+h, h/2);
} else {
bits[i] = pe > th;
set_bit(bits, i, pe > th);
}
}
public:
int operator()(uint8_t *frozen_bits, int level, long double erasure_probability = 0.5L, long double freezing_threshold = 0.5L)
int operator()(uint32_t *frozen_bits, int level, long double erasure_probability = 0.5L, long double freezing_threshold = 0.5L)
{
int length = 1 << level;
freeze(frozen_bits, erasure_probability, freezing_threshold, 0, length / 2);
int K = 0;
int K = length;
for (int i = 0; i < length; ++i)
K += !frozen_bits[i];
K -= (frozen_bits[i/32] >> (i%32)) & 1;
return K;
}
};
@ -36,6 +45,14 @@ public:
template <int MAX_M>
class PolarCodeConst0
{
static void inform_bit(uint32_t *bits, int idx)
{
bits[idx/32] &= ~(1 << (idx%32));
}
static void frozen_bit(uint32_t *bits, int idx)
{
bits[idx/32] |= 1 << (idx%32);
}
void compute(long double pe, int i, int h)
{
if (h) {
@ -48,7 +65,7 @@ class PolarCodeConst0
long double prob[1<<MAX_M];
int index[1<<MAX_M];
public:
void operator()(uint8_t *frozen_bits, int level, int K, long double erasure_probability = std::exp(-1.L))
void operator()(uint32_t *frozen_bits, int level, int K, long double erasure_probability = std::exp(-1.L))
{
assert(level <= MAX_M);
int length = 1 << level;
@ -57,9 +74,9 @@ public:
index[i] = i;
std::nth_element(index, index+K, index+length, [this](int a, int b){ return prob[a] < prob[b]; });
for (int i = 0; i < K; ++i)
frozen_bits[index[i]] = 0;
inform_bit(frozen_bits, index[i]);
for (int i = K; i < length; ++i)
frozen_bits[index[i]] = 1;
frozen_bit(frozen_bits, index[i]);
}
};