1. Akos Ledeczi EECE 6354, Fall 2017 Vanderbilt University
Memory Management
Akos Ledeczi
EECE 6354, Fall 2017
Vanderbilt University

2. Memory Partitions
Dynamic memory allocation from the heap /malloc() and free()/ can lead to memory fragmentation
µC/OS-III provides memory partitions as an alternative
Can create multiple partitions with different block sizes

3. Usage
OS_MEM MyPartition; CPU_INT08U Storage[12][100]; /* malloc() also works */ void main() { … OSMemCreate(&MyPartition, “My partition”, (void *)&Storage[0][0], 12,100, &err); } void MyTask(void *p_arg) CPU_INT08U *block = (CPU_INT08U *)OSMemGet(&MyPartition,&err); /* allocate */ if (err == OS_ERR_NONE) { OSMemPut(&MyPartition,block,&err); /* deallocate */

4. Example
Memory block is not typed: reader and write “agrees” on the content’s format
Once message is written and posted in the queue, originator must not touch it
Once message received and processed, memory block is put back in the partition
To prevent problems if partition runs out of available blocks, a semaphore can be used to control access to it