void CompassCalibrator::thin_samples() {
if(_sample_buffer == nullptr) {
return;
}
_samples_thinned = 0;
// shuffle the samples http://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle
// this is so that adjacent samples don't get sequentially eliminated
for(uint16_t i=_samples_collected-1; i>=1; i--) {
uint16_t j = get_random16() % (i+1);
CompassSample temp = _sample_buffer[i];
_sample_buffer[i] = _sample_buffer[j];
_sample_buffer[j] = temp;
}
for(uint16_t i=0; i < _samples_collected; i++) {
if(!accept_sample(_sample_buffer[i])) {
_sample_buffer[i] = _sample_buffer[_samples_collected-1];
_samples_collected --;
_samples_thinned ++;
}
}
update_completion_mask();
}
int http_handshake(int fd, const char *host, const char *service,
const char *path, std::string& body)
{
char buf[4096];
std::string client_key = base64(get_random16());
snprintf(buf, sizeof(buf),
"GET %s HTTP/1.1\r\n"
"Host: %s:%s\r\n"
"Upgrade: websocket\r\n"
"Connection: Upgrade\r\n"
"Sec-WebSocket-Key: %s\r\n"
"Sec-WebSocket-Version: 13\r\n"
"\r\n",
path, host, service, client_key.c_str());
std::string reqheader = buf;
if(send_http_handshake(fd, reqheader) == -1) {
return -1;
}
std::string resheader;
if(recv_http_handshake(fd, resheader) == -1) {
return -1;
}
std::string::size_type keyhdstart;
if((keyhdstart = resheader.find("Sec-WebSocket-Accept: ")) ==
std::string::npos) {
std::cerr << "http_upgrade: missing required headers" << std::endl;
return -1;
}
keyhdstart += 22;
std::string::size_type keyhdend = resheader.find("\r\n", keyhdstart);
std::string accept_key = resheader.substr(keyhdstart, keyhdend-keyhdstart);
if(accept_key == create_acceptkey(client_key)) {
body = resheader.substr(resheader.find("\r\n\r\n")+4);
return 0;
} else {
return -1;
}
}
// generate a random float between -1 and 1
static float rand_num(void)
{
return ((2.0f * get_random16()) / 0xFFFF) - 1.0f;
}
