failed approach

gomspace/libutil/src/time.c

@@ -0,0 +1,28 @@
+/* Copyright (c) 2013-2017 GomSpace A/S. All rights reserved. */
+
+#include <gs/util/time.h>
+
+uint32_t gs_time_diff_ms(uint32_t ref_ms, uint32_t now_ms)
+{
+    if (now_ms >= ref_ms) {
+        return (now_ms - ref_ms);
+    }
+
+    // assuming time wrapped at max uint32_t
+    return ((UINT32_MAX - ref_ms) + now_ms);
+}
+
+bool gs_time_sleep_until_ms(uint32_t * ref_ms, uint32_t sleep_ms)
+{
+    const uint32_t now = gs_time_rel_ms();
+    *ref_ms += sleep_ms; // this is expected to be in the future
+    uint32_t ms = gs_time_diff_ms(now, *ref_ms);
+    if (ms > sleep_ms) {
+        // we are behind - catch up, could be bad seed or too long processing
+        *ref_ms = now;
+        gs_time_sleep_ms(0); // yield - let others have a go
+        return true;
+    }
+    gs_time_sleep_ms(ms);
+    return false;
+}