#include <vector>
#include <algorithm>
#include <cstdint>
#include "message.h"
void send_message(std::vector<bool> M, std::vector<bool> C) {
int S = M.size();
// Prepend 11-bit representation of S (big-endian)
std::vector<bool> M_padded;
for (int i = 10; i >= 0; i--) {
M_padded.push_back((S >> i) & 1);
}
for (bool b : M) {
M_padded.push_back(b);
}
int total_bits = M_padded.size();
int D = (total_bits + 15) / 16; // ceil division
// Pad to D*16 bits
M_padded.resize(D * 16, false);
// Send pattern: 31 packets
for (int i = 0; i < 31; i++) {
std::vector<bool> packet(31, C[i]); // if C[i] is true, then all ones; else all zeros.
send_packet(packet);
}
// Get safe indices (where C[j] is false) and sort
std::vector<int> safe_indices;
for (int j = 0; j < 31; j++) {
if (!C[j]) {
safe_indices.push_back(j);
}
}
std::sort(safe_indices.begin(), safe_indices.end());
// Send data packets
for (int i = 0; i < D; i++) {
std::vector<bool> packet(31, false); // all zeros by default
for (int j = 0; j < 16; j++) {
int idx = safe_indices[j];
packet[idx] = M_padded[i * 16 + j];
}
send_packet(packet);
}
}
std::vector<bool> receive_message(std::vector<std::vector<bool>> R) {
int num_packets = R.size();
if (num_packets < 31) {
// Not enough packets, return empty
return std::vector<bool>();
}
// Reconstruct C_recv from the first 31 packets
std::vector<bool> C_recv(31, false);
for (int i = 0; i < 31; i++) {
const std::vector<bool>& pkt = R[i];
int cnt = 0;
for (bool b : pkt) {
if (b) cnt++;
}
C_recv[i] = (cnt >= 16); // if at least 16 ones, then true (1)
}
// Get safe indices from C_recv (where it is false) and sort
std::vector<int> safe_indices;
for (int j = 0; j < 31; j++) {
if (!C_recv[j]) {
safe_indices.push_back(j);
}
}
std::sort(safe_indices.begin(), safe_indices.end());
int D = num_packets - 31; // number of data packets
std::vector<bool> M_total;
for (int i = 31; i < num_packets; i++) {
const std::vector<bool>& pkt = R[i];
for (int j = 0; j < safe_indices.size(); j++) {
int idx = safe_indices[j];
M_total.push_back(pkt[idx]);
}
}
// If we don't have at least 11 bits, return empty
if (M_total.size() < 11) {
return std::vector<bool>();
}
// Decode the length (first 11 bits, big-endian)
int len = 0;
for (int i = 0; i < 11; i++) {
len = (len << 1) | (M_total[i] ? 1 : 0);
}
// Check if we have enough bits for the message
if (M_total.size() < 11 + len) {
// Not enough, return empty
return std::vector<bool>();
}
// Extract the message
std::vector<bool> message;
for (int i = 0; i < len; i++) {
message.push_back(M_total[11 + i]);
}
return message;
}
