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microseconds resolution

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This commit is contained in:
folkert van heusden 2024-05-07 14:22:40 +02:00
parent 5f8b2028a5
commit 8c8084ec5b
Signed by untrusted user who does not match committer: folkert
GPG key ID: 6B6455EDFEED3BD1
1 changed files with 37 additions and 24 deletions
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61
ESP32/FvHNTP/FvHNTP.cpp
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@ -32,6 +32,25 @@ struct sntp_datagram
uint32_t transmit_timestamp_fraq; uint32_t transmit_timestamp_fraq;
}; };
uint64_t get_us_from_ntp(const uint32_t high, const uint32_t low)
{
return uint64_t(ntohl(high)) * 1000000ll + ntohl(low) / 4295;
}
uint64_t micros64()
{
static uint32_t low32 = 0, high32 = 0;
uint32_t new_low32 = micros();
if (new_low32 < low32)
high32++;
low32 = new_low32;
return (uint64_t(high32) << 32) | low32;
}
ntp::ntp(const std::string & server): server(server) ntp::ntp(const std::string & server): server(server)
{ {
} }
@ -51,21 +70,16 @@ void ntp::begin()
th = new std::thread(std::ref(*this)); th = new std::thread(std::ref(*this));
} }
std::optional<uint64_t> ntp::get_unix_epoch_ms() std::optional<uint64_t> ntp::get_unix_epoch_us()
{ {
std::unique_lock<std::mutex> lck(lock); std::unique_lock<std::mutex> lck(lock);
if (ntp_at_ts == 0) if (ntp_at_ts == 0)
return { }; return { };
auto now = millis(); auto now = micros64();
return ntp_at_ts + now - millis_at_ts - NTP_EPOCH * 1000; return ntp_at_ts + now - micros_at_ts - NTP_EPOCH * 1000000l;
}
uint64_t get_ms_from_ntp(const uint32_t high, const uint32_t low)
{
return uint64_t(ntohl(high)) * 1000ll + ntohl(low) / (4295 * 1000);
} }
void ntp::operator()() void ntp::operator()()
@ -87,11 +101,11 @@ void ntp::operator()()
packet_out.stratum = 14; packet_out.stratum = 14;
packet_out.poll = 2; packet_out.poll = 2;
auto now = get_unix_epoch_ms(); auto now = get_unix_epoch_us();
if (now.has_value()) { if (now.has_value()) {
uint64_t sec = now.value() / 1000; uint64_t sec = now.value() / 1000000l;
uint64_t usec = (now.value() % 1000) * 1000; uint64_t usec = now.value() % 1000000l;
packet_out.originate_timestamp_secs = htonl(sec + NTP_EPOCH); // T1 packet_out.originate_timestamp_secs = htonl(sec + NTP_EPOCH); // T1
packet_out.originate_timestamp_fraq = htonl(usec * 4295); packet_out.originate_timestamp_fraq = htonl(usec * 4295);
@ -103,37 +117,36 @@ void ntp::operator()()
// TODO verify source address // TODO verify source address
if (recvfrom(fd, &packet_in, sizeof(packet_in), 0, nullptr, nullptr) == sizeof(packet_in)) { if (recvfrom(fd, &packet_in, sizeof(packet_in), 0, nullptr, nullptr) == sizeof(packet_in)) {
// TODO verify version etc // TODO verify version etc
uint32_t now = millis(); uint64_t now = micros64();
auto t_t4 = get_unix_epoch_ms(); auto t_t4 = get_unix_epoch_us();
std::unique_lock<std::mutex> lck(lock); std::unique_lock<std::mutex> lck(lock);
s = 60; s = 60;
if (t_t4.has_value()) { if (t_t4.has_value()) {
int64_t t1 = get_ms_from_ntp(packet_out.originate_timestamp_secs, packet_out.originate_timestamp_fraq); int64_t t1 = get_us_from_ntp(packet_out.originate_timestamp_secs, packet_out.originate_timestamp_fraq);
int64_t t2 = get_ms_from_ntp(packet_in.receive_timestamp_seqs, packet_in.receive_timestamp_fraq ); int64_t t2 = get_us_from_ntp(packet_in.receive_timestamp_seqs, packet_in.receive_timestamp_fraq );
int64_t t3 = get_ms_from_ntp(packet_in.transmit_timestamp_secs, packet_in.transmit_timestamp_fraq ); int64_t t3 = get_us_from_ntp(packet_in.transmit_timestamp_secs, packet_in.transmit_timestamp_fraq );
int64_t t4 = t_t4.value() + NTP_EPOCH * 1000; int64_t t4 = t_t4.value() + NTP_EPOCH * 1000000l;
auto offset = ((t2 - t1) + (t3 - t4)) / 2; auto offset = ((t2 - t1) + (t3 - t4)) / 2;
// TODO handle millis wrap
if (offset > 0) { if (offset > 0) {
if (offset < millis_at_ts) if (offset < micros_at_ts)
millis_at_ts -= offset; micros_at_ts -= offset;
else { else {
millis_at_ts = 0; micros_at_ts = 0;
s = 4; s = 4;
} }
} }
else { else {
millis_at_ts -= offset; micros_at_ts -= offset;
} }
} }
else { else {
ntp_at_ts = get_ms_from_ntp(packet_in.transmit_timestamp_secs, packet_in.transmit_timestamp_fraq); ntp_at_ts = get_us_from_ntp(packet_in.transmit_timestamp_secs, packet_in.transmit_timestamp_fraq);
millis_at_ts = now; micros_at_ts = now;
} }
} }
} }