Time System

Source: src/dusk/time/, platform layers in src/dusk<platform>/time/

Global state

extern dusktime_t TIME;

typedef struct {
  float_t delta;   // Fixed step size in seconds (DUSK_TIME_STEP)
  float_t time;    // Accumulated game time in seconds

  // Only present when DUSK_TIME_DYNAMIC is defined:
  float_t lastNonDynamic;
  bool_t dynamicUpdate;   // true on sub-step ticks
  float_t dynamicDelta;   // real elapsed seconds this frame
  float_t dynamicTime;    // accumulated real time
} dusktime_t;

Fixed vs dynamic timestep

Fixed timestep (default)

DUSK_TIME_STEP defaults to 16ms / 1000 = 0.016f seconds (62.5 Hz). Every call to timeUpdate() advances TIME.time by exactly DUSK_TIME_STEP and sets TIME.delta = DUSK_TIME_STEP. This is the safe, deterministic mode for physics and game logic.

Dynamic timestep (`DUSK_TIME_DYNAMIC`)

When enabled, timeUpdate() calls the platform tick hook to measure actual elapsed time. It fires a "non-dynamic" step (dynamicUpdate = false, delta = DUSK_TIME_STEP) once per fixed interval, and "dynamic" sub-steps (dynamicUpdate = true) in between. Systems that must run on the fixed interval (physics, networking) skip the dynamic sub-steps by checking:

if(TIME.dynamicUpdate) return;

Platform hooks

Each platform provides three macros in its time/timeplatform.h:

Macro	Purpose
`timeTickPlatform()`	Sample the hardware timer
`timeGetDeltaPlatform()`	Return seconds since last tick
`timeGetRealPlatform()`	Return epoch seconds since 1970
`timeGetRealTimeZonePlatform()`	Return local timezone offset (seconds)

timeTickPlatform and timeGetDeltaPlatform are only required when DUSK_TIME_DYNAMIC is defined.

Platform implementations

Platform	Tick source	Real time source
Linux	`SDL_GetTicks64()` (via SDL2)	`clock_gettime(CLOCK_REALTIME)`
Knulli	`SDL_GetTicks64()` (via SDL2)	`clock_gettime(CLOCK_REALTIME)`
PSP	`SDL_GetTicks64()` (via SDL2)	`sceRtcGetCurrentTick()` (microseconds)
GameCube	none (fixed step only)	`ticks_to_microsecs(__SYS_GetSystemTime())` + 2000->1970 offset
Wii	none (fixed step only)	same as GameCube

GameCube / Wii note: the hardware timer returns ticks since 2000-01-01, so an offset of 946684800 seconds is added to convert to UNIX epoch. The timezone offset is always returned as 0.0 on Dolphin (timezone is not available without network time).

Epoch time (`timeepoch.h`)

typedef struct {
  double_t time;        // raw UTC seconds since 1970
  double_t timeZone;    // timezone offset in seconds
  double_t offsetTime;  // time + timeZone
} dusktimeepoch_t;

dusktimeepoch_t timeGetEpoch(void);
// Returns current time in local timezone.

Epoch helpers

int32_t timeEpochGetYear(epoch);
int32_t timeEpochGetMonth(epoch);     // 1-12
int32_t timeEpochGetDayOfMonth(epoch); // 1-31
int32_t timeEpochGetHours(epoch);     // 0-23
int32_t timeEpochGetMinutes(epoch);   // 0-59
int32_t timeEpochGetSeconds(epoch);   // 0-59
bool_t  timeEpochIsLeapYear(year);

size_t timeEpochFormat(
  dusktimeepoch_t epoch,
  const char_t *format,  // %Y %m %d %H %M %S
  char_t *buffer,
  size_t bufferSize
);

Adding a new platform time implementation

Create src/dusk<platform>/time/time<platform>.h/.c.
Implement timeGetReal<Platform>() and timeGetRealTimeZone<Platform>().
If DUSK_TIME_DYNAMIC: also implement timeTick<Platform>() and timeGetDelta<Platform>().
Create src/dusk<platform>/time/timeplatform.h with the #define macros pointing to your functions.

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