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# Manual Reference Pages  -  TAIA (3)

### NAME

taia - manipulate times with 1-attosecond precision

Syntax
Description
Arithmetic

### SYNTAX

#include <taia.h>

double taia_approx(&t);
double taia_frac(&t);
void taia_tai(&t,&sec);

int taia_less(&a,&b);
void taia_sub(&t,&a,&b);
void taia_half(&t,&a);

unsigned int taia_fmtfrac(s,&t);

struct taia t;
struct taia a;
struct taia b;
struct tai sec;
char *s;

### 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.

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.