File indexing completed on 2024-05-12 15:58:26

 /*
  *  SPDX-FileCopyrightText: 2014 Dmitry Kazakov <dimula73@gmail.com>
  *
  *  SPDX-License-Identifier: GPL-2.0-or-later
  */
 
 #ifndef __KIS_LOCK_FREE_LOD_COUNTER_H
 #define __KIS_LOCK_FREE_LOD_COUNTER_H
 
 #include <QAtomicInt>
 
 
 class KisLockFreeLodCounter
 {
 public:
     void addLod(int newLod) {
         int oldValue = 0;
         int newValue = 0;
 
         do {
             oldValue = m_num;
 
             int counter;
             int lod;
             unpackLod(oldValue, &counter, &lod);
 
             if (!counter) {
                 lod = newLod;
             } else {
                 Q_ASSERT(lod == newLod);
             }
 
             counter++;
             newValue = packLod(counter, lod);
         } while(!m_num.testAndSetOrdered(oldValue, newValue));
     }
 
     void removeLod() {
         int oldValue = 0;
         int newValue = 0;
 
         do {
             oldValue = m_num;
 
             int counter;
             int lod;
             unpackLod(oldValue, &counter, &lod);
 
             Q_ASSERT(counter > 0);
 
             counter--;
             newValue = packLod(counter, lod);
         } while(!m_num.testAndSetOrdered(oldValue, newValue));
     }
 
     int readLod() const {
         int value = m_num;
 
         int counter;
         int lod;
         unpackLod(value, &counter, &lod);
 
         return counter ? lod : -1;
     }
 
     void testingClear() {
         m_num = 0;
     }
 
 private:
     static inline int packLod(int counter, int lod) {
         return (counter << 8) | (lod & 0xFF);
     }
 
     static inline void unpackLod(int value, int *counter, int *lod) {
         *lod = value & 0xFF;
         *counter = value >> 8;
     }
 
 private:
     QAtomicInt m_num;
 };
 
 #endif /* __KIS_LOCK_FREE_LOD_COUNTER_H */