From cc945cad053cd36d67ee5daf50a71e212ce2cfe3 Mon Sep 17 00:00:00 2001
From: 3gg <3gg@shellblade.net>
Date: Tue, 8 Jul 2025 08:39:27 -0700
Subject: Fixes, add time_add

---
 timer/include/timer.h |  5 ++++-
 timer/src/timer.c     | 15 +++++++++++++--
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/timer/include/timer.h b/timer/include/timer.h
index 94781d6..6dc87d9 100644
--- a/timer/include/timer.h
+++ b/timer/include/timer.h
@@ -20,7 +20,7 @@ typedef struct timespec time_point;
 typedef uint64_t time_delta;
 
 /// A high resolution timer.
-typedef struct {
+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.
@@ -53,6 +53,9 @@ time_delta sec_to_time_delta(double seconds);
 /// Convert the time point to nanoseconds.
 uint64_t time_point_to_ns(time_point);
 
+/// Add a time delta to a timestamp.
+time_point time_add(time_point, time_delta);
+
 /// Put the caller thread to sleep for the given amount of time.
 void time_sleep(time_delta dt);
 
diff --git a/timer/src/timer.c b/timer/src/timer.c
index 340cd98..d886f59 100644
--- a/timer/src/timer.c
+++ b/timer/src/timer.c
@@ -78,7 +78,7 @@ time_delta sec_to_time_delta(double seconds) {
 #ifdef _WIN32
   return (time_delta)(seconds / seconds_per_count);
 #else
-  return (time_delta)(seconds * nanoseconds);
+  return (time_delta)(seconds * 1.0e9);
 #endif
 }
 
@@ -90,9 +90,20 @@ uint64_t time_point_to_ns(time_point t) {
 #endif
 }
 
+time_point time_add(time_point t, time_delta dt) {
+  time_point out;
+#ifdef _WIN32
+  out = t + dt;
+#else
+  out.tv_sec  = t.tv_sec + (__time_t)(dt / nanoseconds);
+  out.tv_nsec = t.tv_nsec + (__time_t)(dt % nanoseconds);
+#endif
+  return out;
+}
+
 void time_sleep(time_delta dt) {
 #ifdef _WIN32
-  const int64_t ms = dt / microseconds;
+  const uint64_t ms = dt / microseconds;
   Sleep((DWORD)(ms));
 #else
   const uint64_t  sec = dt / nanoseconds;
-- 
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