taia

## Name

taia — manipulate times with 1-attosecond precision

## Synopsis

    #include <taia.h>

    double \fBtaia_approx\fP(&\fIt\fR);

    double \fBtaia_frac\fP(&\fIt\fR);

    void \fBtaia_tai\fP(&\fIt\fR,&\fIsec\fR);

    int \fBtaia_less\fP(&\fIa\fR,&\fIb\fR);

    void \fBtaia_add\fP(&\fIt\fR,&\fIa\fR,&\fIb\fR);

    void \fBtaia_sub\fP(&\fIt\fR,&\fIa\fR,&\fIb\fR);

    void \fBtaia_half\fP(&\fIt\fR,&\fIa\fR);

    unsigned int \fBtaia_fmtfrac\fP(\fIs\fR,&\fIt\fR);

    struct taia \fIt\fR;

    struct taia \fIa\fR;

    struct taia \fIb\fR;

    struct tai \fIsec\fR;

    char *\fIs\fR;

## Description

A struct taia stores an integer between 0 inclusive and 2^64x10^18 exclusive. The format of struct taia is designed to speed up common operations; applications should not look inside struct taia\fR. A struct taia variable is commonly used to store a TAI64NA label. Each TAI64NA label refers to one attosecond of real time; see http://pobox.com/~djb/proto/tai64.txt for more information. The integer in the struct taia is 10^18 times the second count, plus 10^9 times the nanosecond count, plus the attosecond count. A struct taia variable may also be used to store the numerical difference between two TAI64NA labels.

## Arithmetic

taia_approx returns a double-precision approximation to `t`/10^18. The result of taia_approx is always nonnegative. taia_tai places into `sec` the integer part of `t`/10^18. taia_frac returns a double-precision approximation to the fraction part of `t`/10^18. The result of taia_frac is always nonnegative. taia_less returns 1 if `a` is smaller than `b`, 0 otherwise. taia_add adds `a` and `b` modulo 2^64x10^18 and puts the result into `t`. The inputs and outputs may overlap. taia_sub subtracts `b` from `a` modulo 2^64x10^18 and puts the result into `t`. The inputs and outputs may overlap. taia_half divides `a` by 2, rounding down, and puts the result into `t`. The input and output may overlap.

## Formatting

taia_fmtfrac prints the remainder of `t`/10^18, padded to exactly 18 digits, into the character buffer `s`, without a terminating NUL. 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 NUL.

## See also

taia_now(3)
taia_pack(3)
tai(3)

## Author

Original code and documentation by Daniel J. Bernstein. Converted to DocBook XML by Jonathan de Boyne Pollard.