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@@ -68,13 +68,31 @@ typedef struct {
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uint8_t stratum; /* clock stratum */
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int8_t poll; /* polling interval */
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int8_t precision; /* precision of the local clock */
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- int32_t rtdelay; /* total rt delay, as a fixed point num. see macros */
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- uint32_t rtdisp; /* like above, but for max err to primary src */
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+ union {
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+ int32_t rtdelay; /* total rt delay, as a fixed point num. see macros */
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+ struct {
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+ uint16_t rtdelay_l16;
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+ uint16_t rtdelay_r16;
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+ };
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+ };
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+ union {
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+ uint32_t rtdisp; /* like above, but for max err to primary src */
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+ struct {
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+ uint16_t rtdisp_l16;
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+ uint16_t rtdisp_r16;
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+ };
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+ };
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uint32_t refid; /* ref clock identifier */
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uint64_t refts; /* reference timestamp. local time local clock */
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uint64_t origts; /* time at which request departed client */
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uint64_t rxts; /* time at which request arrived at server */
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- uint64_t txts; /* time at which request departed server */
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+ union {
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+ uint64_t txts; /* time at which request departed server */
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+ struct {
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+ uint32_t txts_l32;
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+ uint32_t txts_r32;
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+ };
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+ };
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} ntp_message;
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/* this structure holds data about results from querying offset from a peer */
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@@ -167,35 +185,68 @@ static int allow_zero_stratum = 0;
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/* ntp wants seconds since 1/1/00, epoch is 1/1/70. this is the difference */
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#define EPOCHDIFF 0x83aa7e80UL
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+/* extract double from 32-bit ntp fixed point number, without violating strict aliasing rules */
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+double ntp32_to_double(uint32_t n) {
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+ double result = 0;
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+ if (n) {
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+ uint16_t l16 = ntohs((uint16_t) (n >> 16));
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+ uint16_t r16 = ntohs((uint16_t) (n & ((1<<16) - 1)));
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+ result = l16 + ((double) r16/65536.0);
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+ }
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+ return result;
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+}
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/* extract a 32-bit ntp fixed point number into a double */
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-#define NTP32asDOUBLE(x) (ntohs(L16(x)) + (double)ntohs(R16(x))/65536.0)
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+/* #define NTP32asDOUBLE(x) (ntohs(L16(x)) + (double)ntohs(R16(x))/65536.0)*/
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+
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+/* extract double from 64-bit ntp fixed point number, without violating strict aliasing rules */
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+double ntp64_to_double(uint64_t n) {
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+ double result = 0;
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+ if (n) {
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+ uint32_t l32 = ntohl((uint32_t) (n >> 32));
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+ uint32_t r32 = ntohl((uint32_t) (n & ((1ul<<32) - 1)));
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+ result = (l32 - EPOCHDIFF)
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+ + (.00000001*(0.5+(double)(r32/42.94967296)));
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+ }
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+ return result;
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+}
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/* likewise for a 64-bit ntp fp number */
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-#define NTP64asDOUBLE(n) (double)(((uint64_t)n)?\
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- (ntohl(L32(n))-EPOCHDIFF) + \
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- (.00000001*(0.5+(double)(ntohl(R32(n))/42.94967296))):\
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- 0)
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+/* #define NTP64asDOUBLE(n) (double)(((uint64_t)n)?\
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+ (ntohl(L32(n))-EPOCHDIFF) + \
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+ (.00000001*(0.5+(double)(ntohl(R32(n))/42.94967296))):\
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+ 0)*/
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/* convert a struct timeval to a double */
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#define TVasDOUBLE(x) (double)(x.tv_sec+(0.000001*x.tv_usec))
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+struct timeval ntp64_to_tv(uint64_t n) {
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+ struct timeval result = {};
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+ if (n) {
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+ uint32_t l32 = ntohl((uint32_t) (n >> 32));
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+ uint32_t r32 = ntohl((uint32_t) (n & ((1ul<<32) - 1)));
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+ result.tv_sec = l32 - EPOCHDIFF;
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+ result.tv_usec = (int)(0.5+(double)(r32/4294.967296));
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+ }
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+ return result;
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+}
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+
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/* convert an ntp 64-bit fp number to a struct timeval */
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-#define NTP64toTV(n,t) \
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+/* #define NTP64toTV(n,t) \
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do{ if(!n) t.tv_sec = t.tv_usec = 0; \
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else { \
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t.tv_sec=ntohl(L32(n))-EPOCHDIFF; \
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t.tv_usec=(int)(0.5+(double)(ntohl(R32(n))/4294.967296)); \
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} \
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- }while(0)
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+ }while(0) */
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/* convert a struct timeval to an ntp 64-bit fp number */
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-#define TVtoNTP64(t,n) \
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+/* #define TVtoNTP64(t,n) \
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do{ if(!t.tv_usec && !t.tv_sec) n=0x0UL; \
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else { \
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L32(n)=htonl(t.tv_sec + EPOCHDIFF); \
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R32(n)=htonl((uint64_t)((4294.967296*t.tv_usec)+.5)); \
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} \
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- } while(0)
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+ } while(0) */
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/* NTP control message header is 12 bytes, plus any data in the data
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* field, plus null padding to the nearest 32-bit boundary per rfc.
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@@ -212,9 +263,9 @@ static int allow_zero_stratum = 0;
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/* calculate the offset of the local clock */
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static inline double calc_offset(const ntp_message *m, const struct timeval *t){
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double client_tx, peer_rx, peer_tx, client_rx;
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- client_tx = NTP64asDOUBLE(m->origts);
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- peer_rx = NTP64asDOUBLE(m->rxts);
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- peer_tx = NTP64asDOUBLE(m->txts);
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+ client_tx = ntp64_to_double(m->origts);
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+ peer_rx = ntp64_to_double(m->rxts);
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+ peer_tx = ntp64_to_double(m->txts);
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client_rx=TVasDOUBLE((*t));
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return (.5*((peer_tx-client_rx)+(peer_rx-client_tx)));
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}
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@@ -223,10 +274,10 @@ static inline double calc_offset(const ntp_message *m, const struct timeval *t){
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void print_ntp_message(const ntp_message *p){
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struct timeval ref, orig, rx, tx;
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- NTP64toTV(p->refts,ref);
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- NTP64toTV(p->origts,orig);
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- NTP64toTV(p->rxts,rx);
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- NTP64toTV(p->txts,tx);
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+ ref = ntp64_to_tv(p->refts);
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+ orig = ntp64_to_tv(p->origts);
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+ rx = ntp64_to_tv(p->rxts);
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+ tx = ntp64_to_tv(p->txts);
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printf("packet contents:\n");
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printf("\tflags: 0x%.2x\n", p->flags);
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@@ -236,13 +287,13 @@ void print_ntp_message(const ntp_message *p){
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printf("\tstratum = %d\n", p->stratum);
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printf("\tpoll = %g\n", pow(2, p->poll));
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printf("\tprecision = %g\n", pow(2, p->precision));
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- printf("\trtdelay = %-.16g\n", NTP32asDOUBLE(p->rtdelay));
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- printf("\trtdisp = %-.16g\n", NTP32asDOUBLE(p->rtdisp));
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+ printf("\trtdelay = %-.16g\n", ntp32_to_double(p->rtdelay));
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+ printf("\trtdisp = %-.16g\n", ntp32_to_double(p->rtdisp));
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printf("\trefid = %x\n", p->refid);
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- printf("\trefts = %-.16g\n", NTP64asDOUBLE(p->refts));
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- printf("\torigts = %-.16g\n", NTP64asDOUBLE(p->origts));
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- printf("\trxts = %-.16g\n", NTP64asDOUBLE(p->rxts));
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- printf("\ttxts = %-.16g\n", NTP64asDOUBLE(p->txts));
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+ printf("\trefts = %-.16g\n", ntp64_to_double(p->refts));
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+ printf("\torigts = %-.16g\n", ntp64_to_double(p->origts));
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+ printf("\trxts = %-.16g\n", ntp64_to_double(p->rxts));
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+ printf("\ttxts = %-.16g\n", ntp64_to_double(p->txts));
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}
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void print_ntp_control_message(const ntp_control_message *p){
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@@ -290,11 +341,17 @@ void setup_request(ntp_message *p){
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MODE_SET(p->flags, MODE_CLIENT);
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p->poll=4;
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p->precision=(int8_t)0xfa;
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- L16(p->rtdelay)=htons(1);
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- L16(p->rtdisp)=htons(1);
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+ p->rtdelay_l16=htons(1);
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+ p->rtdisp_l16=htons(1);
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gettimeofday(&t, NULL);
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- TVtoNTP64(t,p->txts);
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+
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+ /* This used to use TVtoNTP64 but we ran into issues with strict aliasing/type punning.
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+ * We only used the macro in one place, so it's inlined now */
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+ if (t.tv_usec || t.tv_sec) {
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+ p->txts_l32 = htonl(t.tv_sec + EPOCHDIFF);
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+ p->txts_r32 = htonl((uint64_t) ((4294.967296*t.tv_usec)+.5));
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+ }
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}
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/* select the "best" server from a list of servers, and return its index.
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@@ -464,8 +521,8 @@ double offset_request(const char *host, int *status){
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printf("offset %.10g\n", servers[i].offset[respnum]);
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}
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servers[i].stratum=req[i].stratum;
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- servers[i].rtdisp=NTP32asDOUBLE(req[i].rtdisp);
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- servers[i].rtdelay=NTP32asDOUBLE(req[i].rtdelay);
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+ servers[i].rtdisp=ntp32_to_double(req[i].rtdisp);
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+ servers[i].rtdelay=ntp32_to_double(req[i].rtdelay);
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servers[i].waiting--;
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servers[i].flags=req[i].flags;
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servers_readable--;
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Sebastian Wolf