RTOS Memory Pool A fejezet tartalma: Memóriakészlet létrehozása; Memóriablokk lefoglalása; Memóriablokk felszabadítása. Manage thread-safe fixed-size blocks of dynamic memory. Access a memory pool for the functions osPoolCreate. More... class os::rtos::memory_pool Synchronised memory pool, using the default RTOS allocator. //A better implementation will have to modify heap_x.c! Real-Time Operating System: API and RTX Reference Implementation. Returns address of the allocated memory block or NULL in case of no memory available. Shared memory is one of the basic models to exchange information between threads. The function osMemoryPoolGetName returns the pointer to the name string of the memory pool identified by parameter mp_id or NULL in case of an error. The RTOS kernel needs RAM each time a task, queue, mutex, software timer, semaphore or event group is created. Being thread-safe, they can be accessed from threads and ISRs alike. Allocate a memory block from a memory pool. Memory pool attributes. Static and dynamic RTOS configuration Early RTOSproducts required configuration to be performed at build time – i.e.statically. This can optionally be used for custom memory management systems. Get number of memory blocks available in a Memory Pool. The block is initialized to zero. Working with Memory Pools . //This is a primitive and inefficient wrapper around the existing FreeRTOS memory management. A Memory Pool can be seen as a linked list of available (unused) memory blocks of fixed and equal size. Using memory pools for exchanging data, you can share more complex objects between threads if compared to a Message Queue. Must be the size of a memory pool control block object or larger. Get number of memory blocks used in a Memory Pool. If they are available in the RTOS, consider using them for dynamic memory allocation. The function osMemoryPoolNew creates and initializes a memory pool object and returns the pointer to the memory pool object identifier or NULL in case of an error. When the value osFeature_Pool is 1 memory pools are supported. The total amount of memory needed is at least block_count * block_size. Shared memory is one of the basic models to exchange information between threads. A standard memory allocation scheme scans a linked list of indeterminate length to find a free memory block; however, memory allocation has to occur in a fixed time in a RTOS. For developers that need to dynamically allocate memory the block pool is a better choice than heap or byte pools. They operate much faster than the dynamically allocated heap and do not suffer from fragmentation. address of the allocated memory block that is returned to the memory pool. Memory Pool Creation Functions: void os_mempool_construct (os_mempool_t *mempool, const char *name, size_t blocks, size_t block_size_bytes, const os_mempool_attr_t *attr): Construct a statically allocated memory pool object instance. In addition, fixed-length memory pools do not need to manage the size of memory blocks, so the size of the management area is smaller and processing is slightly faster. Pointer to a memory location for the data of the memory pool object. The memory pool may be created again using the function osMemoryPoolNew. The memory block is put back to the list of available blocks. Using memory pools for exchanging data, you can share more complex objects between threads if compared to a Message Queue. Follow these steps to create and use a memory pool: Declare a data structure that combines a number of elements: maximum number of blocks (objects) in the memory pool. Real-Time Operating System: API and RTX Reference Implementation, /*----------------------------------------------------------------------------, *---------------------------------------------------------------------------*/, #define MEMPOOL_OBJECTS 16 // number of Memory Pool Objects, // MemPool object not created, handle failure. Freeing memory to the pool (using osMemoryPoolFree) simply rechains the block into the list. Macro Definition Documentation. The function osMemoryPoolGetSpace returns the number of memory blocks available in the memory pool object specified by parameter mp_id or 0 in case of an error. More... Memory pools are fixed-size blocks of memory that are thread-safe. maximum number of memory blocks in memory pool. Follow these steps to create and use a memory pool: Declare a data structure that combines a number of elements: The thread will become READY as soon as at least one block of memory gets available. Generated on Thu Apr 9 2020 15:50:01 for CMSIS-RTOS2 Version 2.1.3 by Arm Ltd. All rights reserved. Allocate a memory block from the memory pool. The size of the memory block passed with cb_mem. Freeing memory to the pool (using osMemoryPoolFree) simply rechains the block into the list. The function osMemoryPoolDelete deletes a memory pool object specified by parameter mp_id. A block pool on the other hand comes in fixed blocks that not only can be allocated deterministically but also will not fragment. Inter-Thread Communication and Resource Sharing. An RTOS uses signals, memory pools and queues to implement inter-process communication (IPC). Return an allocated memory block back to a specific memory pool. timed-wait semantics). If another thread is waiting for memory to become available the thread is put to READY state. Threads can't talk directly to each other in an RTOS. Exceptions: None. address of the allocated memory block to be returned to the memory pool. Being thread-safe, they can be accessed from threads and ISRs alike.
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