lwpa_timer

Overview

Platform-neutral system timers.

#include "lwpa_timer.h"

Data Structures
struct	LwpaTimer
	A millisecond-resolution timer. More...

Macros
#define	lwpa_timer_start(lwpatimerptr, intval)
	Start a timer. More...
#define	lwpa_timer_reset(lwpatimerptr)   (((lwpatimerptr)->reset_time) = lwpa_getms())
	Reset a timer while keeping the same interval. More...
#define	lwpa_timer_elapsed(lwpatimerptr)   (lwpa_getms() - (lwpatimerptr)->reset_time)
	Get the time since a timer was reset. More...
#define	lwpa_timer_isexpired(lwpatimerptr)    (((lwpatimerptr)->interval == 0) || (lwpa_timer_elapsed(lwpatimerptr) > (lwpatimerptr)->interval))
	Check to see if a timer is expired. More...

Typedefs
typedef struct LwpaTimer	LwpaTimer
	A millisecond-resolution timer. More...

Functions
uint32_t	lwpa_getms ()
	Get a monotonically-increasing millisecond value. More...
uint32_t	lwpa_timer_remaining (const LwpaTimer *timer)
	Get the amount of time remaining in a timer. More...

Macro Definition Documentation

lwpa_timer_elapsed

#define lwpa_timer_elapsed

(

lwpatimerptr

)

(lwpa_getms() - (lwpatimerptr)->reset_time)

Get the time since a timer was reset.

Parameters

lwpatimerptr

Pointer to the LwpaTimer of which to get the elapsed time.

Returns

Number of milliseconds since the timer was reset.

lwpa_timer_isexpired

#define lwpa_timer_isexpired

(

lwpatimerptr

)

(((lwpatimerptr)->interval == 0) || (lwpa_timer_elapsed(lwpatimerptr) > (lwpatimerptr)->interval))

Check to see if a timer is expired.

Parameters

lwpatimerptr

Pointer to the LwpaTimer of which to check the expiration.

Returns

true (more than interval milliseconds have passed since the timer was started/reset) or false (less than or equal to interval milliseconds have passed since the timer was started/reset)

lwpa_timer_reset

#define lwpa_timer_reset

(

lwpatimerptr

)

(((lwpatimerptr)->reset_time) = lwpa_getms())

Reset a timer while keeping the same interval.

Parameters

lwpatimerptr

Pointer to the LwpaTimer to reset.

lwpa_timer_start

#define lwpa_timer_start	(		lwpatimerptr,
			intval
	)

Value:

  do                                           \
  {                                            \
    (lwpatimerptr)->reset_time = lwpa_getms(); \
    (lwpatimerptr)->interval = intval;         \
  } while (0)

Start a timer.

Parameters

lwpatimerptr	Pointer to the LwpaTimer to start.
intval	Timer interval in milliseconds. An interval of 0 will result in a timer that is always expired.

Typedef Documentation

LwpaTimer

typedef struct LwpaTimer LwpaTimer

A millisecond-resolution timer.

The times are represented in milliseconds by a 32-bit unsigned integer. Since the timer is monotonically-increasing, wraparound is handled by doing comparisons of the form

timeA - timeB > 0 

rather than

timeA > timeB 

.

Function Documentation

lwpa_getms()

uint32_t lwpa_getms

(

)

Get a monotonically-increasing millisecond value.

Returns

The current timestamp in milliseconds.

lwpa_timer_remaining()

uint32_t lwpa_timer_remaining

(

const LwpaTimer *

timer

)

Get the amount of time remaining in a timer.

Parameters

timer

Pointer to the LwpaTimer of which to get the remaining time.

Returns

Remaining time in milliseconds or 0 (timer is expired).