Merge pull request #12391 from DEEPIR:master

fix some errors found by static analyzer. (#12391)

* fix possible divided by zero and by negative values

* only 4 elements are used in these arrays

* fix uninitialized member

* use boolean type for semantic boolean variables

* avoid invalid array index

* to avoid exception and because base64_beg is only used in this block

* use std::atomic<bool> to avoid thread control race condition

modules/core/src/parallel_impl.cpp

@@ -337,7 +337,7 @@ public:
     std::atomic<int> completed_thread_count;  // number of threads completed any activities on this job
     int64 dummy2_[8];  // avoid cache-line reusing for the same atomics
 
-    volatile bool is_completed;  // std::atomic_flag ?
+    std::atomic<bool> is_completed;
 
     // TODO exception handling
 };