#include <taia.h>
struct taia t;
A struct taia value is
a number between 0 inclusive and 2^64 exclusive.
The number is a multiple of 10^-18.
The format of struct taia
is designed to speed up common operations;
applications should not look inside struct taia.
A struct taia variable is commonly used to store a TAI64NA label. Each TAI64NA label refers to one attosecond of real time. The number in the struct taia is the second count, plus 10^-9 times the nanosecond count, plus 10^-18 times the attosecond count.
A struct taia variable may also be used to store the numerical difference between two TAI64NA labels.
#include <taia.h>
struct taia t;
taia_now(&t);
taia_now
puts the current time into
t.
More precisely:
taia_now
puts into t
its best guess as to the TAI64NA label for the 1-attosecond interval
that contains the current time.
The current implementation of taia_now assumes that the struct timeval returned by the UNIX gettimeofday function represents the number of TAI seconds since 1970-01-01 00:00:10 TAI. This matches the convention used by the Olson tz library in ``right'' mode. Beware that many clocks are not set accurately, and even the best scientific clocks are nowhere near 1-attosecond accuracy; however, an inaccurate clock may still produce reasonably accurate time differences.
#include <taia.h>
struct taia t;
char buf[TAIA_PACK];
taia_pack(buf,&t);
taia_unpack(buf,&t);
taia_pack converts a TAI64NA label from internal format
in t to
external TAI64NA format
in buf.
taia_pack converts a TAI64NA label from external TAI64NA format in buf to internal format in t.
TAIA_PACK is 16.
#include <taia.h>
struct taia t;
char *s;
unsigned int len;
len = taia_fmtfrac(s,&t);
taia_fmtfrac prints the 18-digit fraction part of t
in decimal,
without a decimal point but with leading zeros,
into the character buffer s,
without a terminating \0.
It returns 18, the number of characters written.
s may be zero;
then taia_fmtfrac returns 18 without printing anything.
The macro TAIA_FMTFRAC is defined as 19; this is enough space for the output of taia_fmtfrac and a terminating \0.
#include <taia.h>
struct taia t;
struct taia a;
struct taia b;
struct tai sec;
double d;
int i;
d = taia_approx(&t);
taia_tai(&t,&sec);
d = taia_frac(&t);
i = taia_less(&a,&b);
taia_add(&t,&a,&b);
taia_sub(&t,&a,&b);
taia_half(&t,&a);
taia_approx
returns a double-precision approximation to
t.
The result of taia_approx is always nonnegative.
taia_tai places into sec the integer part of t. sec is a struct tai variable. If t contains a TAI64NA label then sec will contain the corresponding TAI64 label.
taia_frac returns a double-precision approximation to the fraction part of t. The result of taia_frac is always nonnegative.
taia_less returns 1 if a is less than b, 0 otherwise.
taia_add adds a to b modulo 2^64 and puts the result into t. The inputs and output may overlap.
taia_sub subtracts b from a modulo 2^64 and puts the result into t. The inputs and output may overlap.
taia_half divides a by 2, rounding down to a multiple of 10^-18, and puts the result into t. The input and output may overlap.