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pavel-kirienko / o1heap

Constant-complexity deterministic memory allocator (heap) for hard real-time high-integrity embedded systems. There is very little activity because the project is finished and does not require further changes.

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Feature request: memalign allocation.

tuanhtrng opened this issue · comments

commented

Is it possible to implement O(1) memalign?

commented

I see two solutions immediately (there may be other, less apparent solutions):

  • Non-intrusive solution that you can implement in your application: Given a requirement of $M$ bytes aligned at $A$, invoke $\texttt{o1heapAllocate}\left(\text{instance}, M+A\right)$, then bump the returned pointer to $A$. Do not lose the original pointer as you will need it to deallocate the memory (hint: you may store the original pointer in the allocated fragment).

  • Intrusive solution that requires changes to the library: redefine O1HEAP_ALIGNMENT. This will affect memory consumption/fragmentation for all allocations, though.

commented

I'd like to see a solution where o1heapAllocateOveraligned(O1HeapInstance* const handle, const size_t amount, const size_t alignment) is added to o1heap such that the user doesn't have to implement a pointer mapping scheme outside of o1heap.