From 652c60c362f2b9b57ef6b54b6d3ca0b3051e6a3b Mon Sep 17 00:00:00 2001
From: "Robin.Mueller" <robin.mueller.m@gmail.com>
Date: Wed, 29 Jul 2020 20:02:04 +0200
Subject: [PATCH] important bugfix

I checked all 5 cases for overflows when checking
for missed deadlines (there is current time, timeToWake
and lastWakeTime, with various combinations of overflows)

This should be the correct implementation now
---
 osal/FreeRTOS/FixedTimeslotTask.cpp | 19 +++++++++----------
 osal/FreeRTOS/PeriodicTask.cpp      | 19 +++++++++----------
 2 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/osal/FreeRTOS/FixedTimeslotTask.cpp b/osal/FreeRTOS/FixedTimeslotTask.cpp
index c062101d..17804d90 100644
--- a/osal/FreeRTOS/FixedTimeslotTask.cpp
+++ b/osal/FreeRTOS/FixedTimeslotTask.cpp
@@ -125,19 +125,18 @@ void FixedTimeslotTask::checkMissedDeadline(const TickType_t xLastWakeTime,
      * it. */
     TickType_t currentTickCount = xTaskGetTickCount();
     TickType_t timeToWake = xLastWakeTime + interval;
-    // Tick count has overflown
-    if(currentTickCount < xLastWakeTime) {
-        // Time to wake has overflown as well. If the tick count
-        // is larger than the time to wake, a deadline was missed.
-        if(timeToWake < xLastWakeTime and
-                currentTickCount > timeToWake) {
+    // Time to wake has not overflown.
+    if(timeToWake > xLastWakeTime) {
+        /* If the current time has overflown exclusively or the current
+         * tick count is simply larger than the time to wake, a deadline was
+         * missed */
+        if((currentTickCount < xLastWakeTime) or (currentTickCount > timeToWake)) {
             handleMissedDeadline();
         }
     }
-    // No tick count overflow. If the timeToWake has not overflown
-    // and the current tick count is larger than the time to wake,
-    // a deadline was missed.
-    else if(timeToWake > xLastWakeTime and currentTickCount > timeToWake) {
+    /* Time to wake has overflown. A deadline was missed if the current time
+     * is larger than the time to wake */
+    else if((timeToWake < xLastWakeTime) and (currentTickCount > timeToWake)) {
         handleMissedDeadline();
     }
 }
diff --git a/osal/FreeRTOS/PeriodicTask.cpp b/osal/FreeRTOS/PeriodicTask.cpp
index 44a7b801..91135375 100644
--- a/osal/FreeRTOS/PeriodicTask.cpp
+++ b/osal/FreeRTOS/PeriodicTask.cpp
@@ -108,19 +108,18 @@ void PeriodicTask::checkMissedDeadline(const TickType_t xLastWakeTime,
      * it. */
     TickType_t currentTickCount = xTaskGetTickCount();
     TickType_t timeToWake = xLastWakeTime + interval;
-    // Tick count has overflown
-    if(currentTickCount < xLastWakeTime) {
-        // Time to wake has overflown as well. If the tick count
-        // is larger than the time to wake, a deadline was missed.
-        if(timeToWake < xLastWakeTime and
-                currentTickCount > timeToWake) {
+    // Time to wake has not overflown.
+    if(timeToWake > xLastWakeTime) {
+        /* If the current time has overflown exclusively or the current
+         * tick count is simply larger than the time to wake, a deadline was
+         * missed */
+        if((currentTickCount < xLastWakeTime) or (currentTickCount > timeToWake)) {
             handleMissedDeadline();
         }
     }
-    // No tick count overflow. If the timeToWake has not overflown
-    // and the current tick count is larger than the time to wake,
-    // a deadline was missed.
-    else if(timeToWake > xLastWakeTime and currentTickCount > timeToWake) {
+    /* Time to wake has overflown. A deadline was missed if the current time
+     * is larger than the time to wake */
+    else if((timeToWake < xLastWakeTime) and (currentTickCount > timeToWake)) {
         handleMissedDeadline();
     }
 }