/* $NetBSD: timespecops.c,v 1.2 2020/05/25 20:47:24 christos Exp $ */
/*
* timespecops.c -- calculations on 'struct timespec' values
*
* Written by Juergen Perlinger (
[email protected]) 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-*- */
