#include "transfer.h"
std::vector<int> get_attachment(std::vector<int> source) {
std::vector<int> v;
int x = 0;
for (int i = 0; i < source.size(); i++)
if (source[i]) x ^= (i + 1);
int last = 0;
if (source.size() < 64) {
for (int i = 0; i < 6; i++) {
v.push_back(x & 1);
if (x & 1) last = 1 - last;
x >>= 1;
}
} else {
for (int i = 0; i < 8; i++) {
v.push_back(x & 1);
if (x & 1) last = 1 - last;
x >>= 1;
}
}
v.push_back(last);
return v;
}
std::vector<int> retrieve(std::vector<int> data) {
int last = data.back();
data.pop_back();
int actual_last = 0, x = 0;
if (data.size() < 71) {
for (int i = 0; i < 6; i++) {
x <<= 1;
x += data.back();
if (data.back()) actual_last = 1 - actual_last;
data.pop_back();
}
} else {
for (int i = 0; i < 8; i++) {
x <<= 1;
x += data.back();
if (data.back()) actual_last = 1 - actual_last;
data.pop_back();
}
}
if (actual_last != last) return std::vector<int>(data.begin(), data.end());
int actual_x = 0;
for (int i = 0; i < data.size(); i++) {
if (data[i]) actual_x ^= (i + 1);
}
int error = actual_x ^ x;
if (error == 0) return data;
data[error - 1] = 1 - data[error - 1];
return data;
}
