float time_function()
{
time_t now = time(NULL);
unsigned int runs = 0;
unsigned int time_length = 5; //seconds
while(time(NULL) == now);
now++;
int t = 2;
//setup for funciton here
raw_data rd;
rd.length = 64;
rd.data = (uint8_t*)alloc_named(rd.length, "time_function rd.data");
raw_data rd2 = packet_data(rd, t, 4);
insert_errors2(rd2.data, rd2.length, 0.1442);
raw_data rd3;
while(time(NULL) - time_length < now)
{
unpacket_data(rd2, &rd3, t, 4, NULL);
dealloc(rd3.data);
runs++;
}
//setdown for function here
dealloc(rd.data);
return (float)runs / (float)time_length;
}
int net_send_packet(int sock, struct packet *packet)
{
struct sockaddr_in addr;
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = INADDR_BROADCAST;
addr.sin_port = htons(63322);
return sendto(sock, packet_data(packet), packet_len(packet), 0,
(struct sockaddr *)&addr, sizeof(addr));
}
void test_packeting(unsigned int tries, unsigned int length, float BER, unsigned int rs_t, unsigned int conv_constraint)
{
//tests packeting code.
//Also tests for false positives and false negative decoding.
int correct = 0, incorrect1 = 0, incorrect2 = 0;
unsigned int i;
for(i = 0; i < tries; i++)
{
raw_data rd;
rd.length = length;
rd.data = (uint8_t*)alloc_named(rd.length, "main rd.data");
unsigned int j;
for(j = 0; j < rd.length; j++)
rd.data[j] = rand();
raw_data packet = packet_data(rd, rs_t, conv_constraint);
//insert errors here
insert_errors2(packet.data, packet.length, BER);
raw_data received;
if(unpacket_data(packet, &received, rs_t, conv_constraint, NULL))
{
if(!memcmp(received.data, rd.data, rd.length))
correct++;
else
incorrect1++;
}
else
{
if(memcmp(received.data, rd.data, rd.length))
correct++;
else
{
incorrect2++;
}
}
dealloc(rd.data);
dealloc(packet.data);
dealloc(received.data);
}
printf("correct = %i\n", correct);
printf("false positives = %i\n", incorrect1);
printf("false negatives = %i\n", incorrect2);
}
float coding_gain(float SNR, int t, int tests)
{
table_t snr_ber = read_snr_ber();
float BER = table_lookup(&snr_ber, SNR);
printf("channel BER = %f\n", BER);
unsigned int errors = 0;
unsigned int i;
for(i = 0; i < tests; i++)
{
raw_data rd;
rd.length = 64;
rd.data = (uint8_t*)alloc_named(rd.length, "message_pass_rate rd");
unsigned int j;
for(j = 0; j < 64; j++)
rd.data[j] = rand();
raw_data encoded_packet = packet_data(rd, t, 16);
insert_errors2(encoded_packet.data, encoded_packet.length, BER);
raw_data decoded_packet;
unpacket_data(encoded_packet, &decoded_packet, t, 16, NULL);
for(j = 0; j < rd.length; j++)
{
uint8_t tmp = rd.data[j] ^ decoded_packet.data[j];
unsigned int k;
for(k = 0; k < 8; k++)
{
if(1 << k & tmp)
errors++;
}
}
}
printf("new BER = %f\n", (float)errors / (float)(64 * 8 * tests));
return reverse_table_lookup(&snr_ber, (float)errors / (float)(64 * 8 * tests)) - SNR;
}