Difference between revisions of "How does Optlib initialize the heap?"
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Latest revision as of 21:27, 24 April 2017
How does Optlib initialize the heap? (RL78, RX, ARM targets)
Using the Optimized Library, the heap space is set between 2 pointers when malloc() is first called:
_heap_of_memory _top_of_heap()
_top_of_heap() returns a pointer to the stack pointer:
char* _top_of_heap(void)
{
return stack_ptr;
}
_heap_of memory is set as the address of the label _end. The label is found by default in the project linker script (Debug/projectName_Debug_auto.gsi) as the end of the .bss section. The Optlib uses it to initialize the start of the heap:
if(_heap_of_memory == NULL)
{
_heap_of_memory = &end;
_last_heap_object = &end;
}
If an user wants to define his own heap space with a desired length, he can do that by overwriting the address that the _heap_of_memory and _last_heap_object get and the address that _top_of_heap() returns.
NOTE: Make sure that the given addresses are not reserved and they are part of the RAM section!
