timer.nim

SDL time management routines.

Types

TimerCallback* = proc (interval: uint32; param: pointer): uint32 {...}{.cdecl.}

Procedure prototype for the timer callback procedure.

The callback procedure is passed the current timer interval and returns the next timer interval. If the returned value is the same as the one passed in, the periodic alarm continues, otherwise a new alarm is scheduled. If the callback returns 0, the periodic alarm is cancelled.

TimerID* = cint

Definition of the timer ID type.

Procs

proc getTicks*(): uint32 {...}{.cdecl, importc: "SDL_GetTicks", dynlib: SDL2_LIB.}

Get the number of milliseconds since the SDL library initialization.

This value wraps if the program runs for more than ~49 days.

proc getPerformanceCounter*(): uint64 {...}{.cdecl, importc: "SDL_GetPerformanceCounter", dynlib: SDL2_LIB.}

Get the current value of the high resolution counter.

proc getPerformanceFrequency*(): uint64 {...}{.cdecl, importc: "SDL_GetPerformanceFrequency", dynlib: SDL2_LIB.}

Get the count per second of the high resolution counter.

proc delay*(ms: uint32) {...}{.cdecl, importc: "SDL_Delay", dynlib: SDL2_LIB.}

Wait a specified number of milliseconds before returning.

proc addTimer*(interval: uint32; callback: TimerCallback; param: pointer): TimerID {...}{. cdecl, importc: "SDL_AddTimer", dynlib: SDL2_LIB.}

Add a new timer to the pool of timers already running.

Return a timer ID, or 0 when an error occurs.

proc removeTimer*(id: TimerID): bool {...}{.cdecl, importc: "SDL_RemoveTimer", dynlib: SDL2_LIB.}

Remove a timer knowing its ID.

Return a boolean value indicating success or failure.

Warning: It is not safe to remove a timer multiple times.

Templates

template ticksPassed*(a, b: untyped): bool

Compare SDL ticks values, and return true if a has passed b.

e.g. if you want to wait 100 ms, you could do this:

var timeout: uint32 = getTicks() + 100
while (not ticksPassed(getTicks(), timeout)):
  do work until timeout has elapsed