#include "transfer.h"
std::vector<int> get_attachment(std::vector<int> source) {
int xorsum = 0;
std::vector<int> v;
for (int i = 0; i < (int)source.size(); ++i)
if (source[i]) xorsum ^= i + 1;
for (int i = 0; i < 8; ++i) v.push_back((xorsum>>i)&1);
v.push_back(__builtin_parity(xorsum));
return v;
}
std::vector<int> retrieve(std::vector<int> data) {
int xorsum = 0;
int n = (int)data.size() - 9;
for (int i = 0; i < n; ++i)
if (data[i]) xorsum ^= i + 1;
int xordat = 0, dat_par = data.back();
for (int i = n; i < n + 8; ++i)
xordat ^= (data[i]<<(i-n));
while ((int)data.size() > n) data.pop_back();
if (__builtin_parity(xordat) != dat_par)
return data;
int i = xorsum ^ xordat;
data[i] ^= 1;
return data;
}
