tai

## Name

tai — manipulate times with 1-second precision

## Synopsis

    #include <tai.h>

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

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

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

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

    struct tai \fIt\fR;

    struct tai \fIa\fR;

    struct tai \fIb\fR;

## Description

A struct tai stores an integer between 0 inclusive and 2^64 exclusive. The format of struct tai is designed to speed up common operations; applications should not look inside struct tai\fR. A struct tai variable is commonly used to store a TAI64 label. Each TAI64 label refers to one second of real time. TAI64 labels span a period of hundreds of billions of years. See http://pobox.com/~djb/proto/tai64.txt for more information. A struct tai variable may also be used to store the numerical difference between two TAI64 labels.

## Arithmetic

tai_approx returns a double-precision approximation to `t`. The result of tai_approx is always nonnegative. tai_less returns 1 if `a` is smaller than `b`, 0 otherwise. tai_add adds `a` and `b` modulo 2^64 and puts the result into `t`. The inputs and outputs may overlap. tai_sub subtracts `b` from `a` modulo 2^64 and puts the result into `t`. The inputs and outputs may overlap.

## See also

tai_now(3)
tai_pack(3)
taia(3)
utc(3)

## Author

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