1 files changed, 13 insertions, 4 deletions

diff --git a/timer/include/timer.h b/timer/include/timer.h
index 6dc87d9..75ae367 100644
--- a/timer/include/timer.h
+++ b/timer/include/timer.h
@@ -21,10 +21,10 @@ typedef uint64_t time_delta;
 
 /// A high resolution timer.
 typedef struct Timer {
-  time_point start_time;   // The instant the timer was last started.
-  time_point last_tick;    // The instant the timer was last ticked.
-  time_delta running_time; // Time elapsed since the timer was last started.
-  time_delta delta_time;   // Time elapsed since the last tick.
+  time_point start_time;   ///< The instant the timer was last started.
+  time_point last_tick;    ///< The instant the timer was last ticked.
+  time_delta running_time; ///< Time elapsed since the timer was last started.
+  time_delta delta_time;   ///< Time elapsed since the last tick.
 } Timer;
 
 /// Construct a new timer.
@@ -38,6 +38,15 @@ void timer_start(Timer*);
 /// Update the timer's running and delta times.
 void timer_tick(Timer*);
 
+/// Advance the timer.
+///
+/// This is used for simulations that wish control over time. It should not be
+/// used together with timer_tick().
+///
+/// The input time is relative to the timer's start time. Successive calls to
+/// this function must use increasing values of time.
+void timer_advance(Timer* timer, time_delta t);
+
 /// Get the current time.
 time_point time_now(void);