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Memory Management

Memory Management. Functions. OSMemCreate() Create a partition OSMemGet() Obtaining a memory block OSMemPut() Returning a memory block OSMemQuery() Obtaining status of a memory partition. Memory Control Blocks of μC/OS-II. Memory Partition. Multiple Memory Partitions.

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Memory Management

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  1. Memory Management

  2. Functions • OSMemCreate() Create a partition • OSMemGet() Obtaining a memory block • OSMemPut() Returning a memory block • OSMemQuery() Obtaining status of a memory partition

  3. Memory Control Blocks of μC/OS-II

  4. Memory Partition

  5. Multiple Memory Partitions

  6. Advantages of μC/OS-II • Disadvantages of malloc() • Fragmentation • Nondeterministic running time • Advantages of μC/OS-II • Avoidance of memory fragmentation • Allocation and deallocation a memory block is done in constant time

  7. List of Free Memory Control Blocks

  8. OSMemCreate() OSM_MEM *CommTxBuf; INT8U CommTxPart[100][32]; void main() { INT8U err; OSInit(); /*…*/ CommTxBuf = OSMemCreate(CommTxPart, 100, 32, &err) /*…*/ }

  9. OSMemCreate()

  10. OSMemCreate()

  11. OSMemCreate()

  12. OSMemGet() • You must not use more memory than is available form the memory block. • When you are done using the block, you must return it to the proper memory partition. • Pseudo code • Return a memory block • OSMemFreeList should point to the next memory block

  13. OSMemGet()

  14. OSMemPut() • You should note that OSMemPut() has no way of knowing whether the memory block returned to the partition belongs to that partition.

  15. OSMemPut()

  16. OS_MemQuery()

  17. Using dynamic memory allocation

  18. Using dynamic memory allocation

  19. A blocking system call

  20. A blocking system call

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