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Fixes #3

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Fixes #3

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32 changes: 25 additions & 7 deletions coderedlib.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,10 @@ using namespace std;

#define max_n maxn // Hardcode maximal code length as a compilation parameter maxn

#if max_n < 256
#error "Compilation parameter 'maxn' must be >= 256"
#endif

typedef bitset<max_n> binvec;
typedef vector<binvec> binmat;

Expand Down Expand Up @@ -261,18 +265,22 @@ vector<int> start(size_t beg, size_t end, size_t w)
}

// An helper function to enumerate targets of weight w as follows.
// example enumerating 3 choose 5
// example enumerating 5 choose 3
// 0 1 2 3 4 5
// 01 02 12 03 13 23 04 14 24 34
// 012 013 023 123 014 024 124 034 134 234
// if w is 0, then 5 choose 0 will choose none and leave t invariant.
inline bool next(binvec& t, vector<int>& e)
{
for (size_t i = 1; i < e.size()-1; ++i)
{
if (e[i] >= 0)
{
// clear codeword from target
t ^= B[e[i]];
if (e[i] < B.size())
t ^= B[e[i]];
else
break;
++e[i];
if (i > 1) e[i] += skip; // Only search a fraction of the space for other indices
}
Expand All @@ -284,15 +292,25 @@ inline bool next(binvec& t, vector<int>& e)
if ((e[i] < e[i+1]) | ((e[i+1] < 0) & (e[i] < e[e.size()-1])) )
{
// add the next codeword
t ^= B[e[i]];
if (e[i] < B.size())
{
t ^= B[e[i]];
return true;
}
else
break;

return true;
}
else
{
// reset the coordinate
e[i] = e[i-1]+1;
// add the codeword
t ^= B[e[i]];
if (e[i] < B.size())
t ^= B[e[i]];
else
break;
// move on to the next coordinate
}
}
Expand All @@ -319,7 +337,7 @@ bool LB(binvec& tt, size_t w2, int goal_w, uint64_t* stats)

// If no goal set, just return the best visited solution
int best_w = goal_w > 0 ? goal_w + 1 : tt.count();
if (best_w==0) best_w=n;
if (best_w==0) best_w=n + 1;

while(next(t, enumerator))
{
Expand All @@ -342,7 +360,7 @@ inline void SizeRed(binvec& t, size_t beg, size_t end)
{
// This is the most critical peace: helping the compiler
// For some reason using (t & P[i]).count() gets slow for n > 1024.
int64_t ham = (t, E[i]).count();
int64_t ham = AND_popcnt(t, E[i]);
if (2*ham > l[i]) t ^= B[i];
}
}
Expand Down Expand Up @@ -381,7 +399,7 @@ bool LBB(binvec& tt, size_t k1, size_t w2, int goal_w, uint64_t* stats)

// If no goal set, just return the best visited solution
int best_w = goal_w > 0 ? goal_w + 1 : tt.count();
if (best_w==0) best_w=n;
if (best_w==0) best_w=n + 1;

bool notover = true;
while(notover)
Expand Down