TIME-SYS

Overview

Provides time-related structures and functions.

Since:

1.0

Version:

1.0

Summary

Files

File Name Description
time.h Provides structures and functions related to the system time.

Data Structures

Data Structure Name Description
timeval Describes a period of time, accurate to microseconds.
timespec Describes a period of time, accurate to nanoseconds.
itimerval Describes a timer.
timezone Describes a time zone.

Macros

Macro Name and Value Description
ITIMER_REAL    0 Defines the timer that runs in real time.

Functions

Function Name Description
gettimeofday (struct timeval __restrict value, void restrict ovalue) int Obtains the system time and time zone.
getitimer (int w, struct itimerval old) int Obtains the value of an intermittent timer.
setitimer (int w, const struct itimerval restrict value, struct itimerval __restrict ovalue) int Sets the value for a timer.
settimeofday (const struct timeval tv, const struct timezone *tz) int Sets the system time and time zone.

Details

Function Documentation

getitimer()


1. int getitimer (int w, struct [itimerval]($api-api-SmartVision-Devices-itimerval.md) * old )

Description:

Obtains the value of an intermittent timer.

Parameters:

Name Description
w Indicates the timer type. Only ITIMER_REAL is supported.
old Indicates the pointer to the timer value.

Returns:

Returns 0 if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno Description
EINVAL Incorrect input or timer type.

gettimeofday()


1. int gettimeofday (struct [timeval]($api-api-SmartVision-Devices-timeval.md) *__restrict value, void *__restrict ovalue )

Description:

Obtains the system time and time zone.

Parameters:

Name Description
value Indicates the pointer to the timeval structure that contains the time.
ovalue This parameter is used for compatibility only.

Attention:

Currently, there is no time zone structure. The return value of ovalue is empty.

Returns:

Returns 0 if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno Description
EINVAL Incorrect input.

setitimer()


1. int setitimer (int w, const struct [itimerval]($api-api-SmartVision-Devices-itimerval.md) *__restrict value, struct [itimerval]($api-api-SmartVision-Devices-itimerval.md) *__restrict ovalue )

Description:

Sets the value for a timer.

Parameters:

Name Description
w Indicates the timer type. Currently, only ITIMER_REAL is supported.
value Indicates the pointer to the timer value to set.
ovalue Indicates the pointer to the original timer value before the current setting, which can be NULL.

Returns:

Returns 0 if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno Description
EINVAL Incorrect input or timer type.

settimeofday()


1. int settimeofday (const struct [timeval]($api-api-SmartVision-Devices-timeval.md) * tv, const struct [timezone]($api-api-SmartVision-Devices-timezone.md) * tz )

Description:

Sets the system time and time zone.

Parameters:

Name Description
tv Indicates the pointer to the time to set.
tz Indicates the pointer to the time zone to set. This parameter is not used yet.

Attention:

tz is invalid. The time is set internally using clock_settime.

Returns:

Returns 0 if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno Description
EINVAL Incorrect input.