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Diffstat (limited to 'libntp/timespecops.c')
| -rw-r--r-- | libntp/timespecops.c | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/libntp/timespecops.c b/libntp/timespecops.c new file mode 100644 index 000000000000..7dd1c6c88eda --- /dev/null +++ b/libntp/timespecops.c @@ -0,0 +1,233 @@ +/* + * timespecops.c -- calculations on 'struct timespec' values + * + * Written by Juergen Perlinger (perlinger@ntp.org) for the NTP project. + * The contents of 'html/copyright.html' apply. + * + */ + +#include "config.h" + +#include <sys/types.h> +#include <stdio.h> +#include <math.h> + +#include "ntp.h" +#include "timetoa.h" +#include "timespecops.h" + + +/* nanoseconds per second */ +#define NANOSECONDS 1000000000 + +/* conversion between l_fp fractions and nanoseconds */ +#ifdef HAVE_U_INT64 +# define FTOTVN(tsf) \ + ((int32) \ + (((u_int64)(tsf) * NANOSECONDS + 0x80000000) >> 32)) +# define TVNTOF(tvu) \ + ((u_int32) \ + ((((u_int64)(tvu) << 32) + NANOSECONDS / 2) / \ + NANOSECONDS)) +#else +# define NSECFRAC (FRAC / NANOSECONDS) +# define FTOTVN(tsf) \ + ((int32)((tsf) / NSECFRAC + 0.5)) +# define TVNTOF(tvu) \ + ((u_int32)((tvu) * NSECFRAC + 0.5)) +#endif + + + +/* make sure nanoseconds are in nominal range */ +struct timespec +normalize_tspec( + struct timespec x + ) +{ +#if SIZEOF_LONG > 4 + long z; + + /* + * tv_nsec is of type 'long', and on a 64-bit machine using only + * loops becomes prohibitive once the upper 32 bits get + * involved. On the other hand, division by constant should be + * fast enough; so we do a division of the nanoseconds in that + * case. The floor adjustment step follows with the standard + * normalisation loops. And labs() is intentionally not used + * here: it has implementation-defined behaviour when applied + * to LONG_MIN. + */ + if (x.tv_nsec < -3l * NANOSECONDS || + x.tv_nsec > 3l * NANOSECONDS) { + z = x.tv_nsec / NANOSECONDS; + x.tv_nsec -= z * NANOSECONDS; + x.tv_sec += z; + } +#endif + /* since 10**9 is close to 2**32, we don't divide but do a + * normalisation in a loop; this takes 3 steps max, and should + * outperform a division even if the mul-by-inverse trick is + * employed. */ + if (x.tv_nsec < 0) + do { + x.tv_nsec += NANOSECONDS; + x.tv_sec--; + } while (x.tv_nsec < 0); + else if (x.tv_nsec >= NANOSECONDS) + do { + x.tv_nsec -= NANOSECONDS; + x.tv_sec++; + } while (x.tv_nsec >= NANOSECONDS); + + return x; +} + +/* x = abs(a) */ +struct timespec +abs_tspec( + struct timespec a + ) +{ + struct timespec c; + + c = normalize_tspec(a); + if (c.tv_sec < 0) { + if (c.tv_nsec != 0) { + c.tv_sec = -c.tv_sec - 1; + c.tv_nsec = NANOSECONDS - c.tv_nsec; + } else { + c.tv_sec = -c.tv_sec; + } + } + + return c; +} + +/* + * compare previously-normalised a and b + * return 1 / 0 / -1 if a < / == / > b + */ +int +cmp_tspec( + struct timespec a, + struct timespec b + ) +{ + int r; + + r = (a.tv_sec > b.tv_sec) - (a.tv_sec < b.tv_sec); + if (0 == r) + r = (a.tv_nsec > b.tv_nsec) - + (a.tv_nsec < b.tv_nsec); + + return r; +} + +/* + * test previously-normalised a + * return 1 / 0 / -1 if a < / == / > 0 + */ +int +test_tspec( + struct timespec a + ) +{ + int r; + + r = (a.tv_sec > 0) - (a.tv_sec < 0); + if (r == 0) + r = (a.tv_nsec > 0); + + return r; +} + +/* + * convert to l_fp type, relative and absolute + */ + +/* convert from timespec duration to l_fp duration */ +l_fp +tspec_intv_to_lfp( + struct timespec x + ) +{ + struct timespec v; + l_fp y; + + v = normalize_tspec(x); + y.l_uf = TVNTOF(v.tv_nsec); + y.l_i = (int32)v.tv_sec; + + return y; +} + +/* convert from l_fp type, relative signed/unsigned and absolute */ +struct timespec +lfp_intv_to_tspec( + l_fp x + ) +{ + struct timespec out; + l_fp absx; + int neg; + + neg = L_ISNEG(&x); + absx = x; + if (neg) { + L_NEG(&absx); + } + out.tv_nsec = FTOTVN(absx.l_uf); + out.tv_sec = absx.l_i; + if (neg) { + out.tv_sec = -out.tv_sec; + out.tv_nsec = -out.tv_nsec; + out = normalize_tspec(out); + } + + return out; +} + +struct timespec +lfp_uintv_to_tspec( + l_fp x + ) +{ + struct timespec out; + + out.tv_nsec = FTOTVN(x.l_uf); + out.tv_sec = x.l_ui; + + return out; +} + +/* + * absolute (timestamp) conversion. Input is time in NTP epoch, output + * is in UN*X epoch. The NTP time stamp will be expanded around the + * pivot time *p or the current time, if p is NULL. + */ +struct timespec +lfp_stamp_to_tspec( + l_fp x, + const time_t * p + ) +{ + struct timespec out; + vint64 sec; + + sec = ntpcal_ntp_to_time(x.l_ui, p); + out.tv_nsec = FTOTVN(x.l_uf); + + /* copying a vint64 to a time_t needs some care... */ +#if SIZEOF_TIME_T <= 4 + out.tv_sec = (time_t)sec.d_s.lo; +#elif defined(HAVE_INT64) + out.tv_sec = (time_t)sec.q_s; +#else + out.tv_sec = ((time_t)sec.d_s.hi << 32) | sec.d_s.lo; +#endif + + return out; +} + +/* -*-EOF-*- */ |