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Deterministic Fixed Allocator

Hard C++ Determinism Asked at Honeywell
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A hard-real-time task cannot use a general allocator because worst-case time is unbounded. Implement a bump allocator with a reset point and prove its allocation is constant time.

Constraints

  • Fixed 4 KB arena, statically allocated.
  • `allocate(bytes, alignment)` returns nullptr when it will not fit.
  • Individual frees are not supported; only a full `reset()`.
  • Allocation must be O(1) with no search.
  • Alignment must be honoured exactly.
  • Must not overflow when bytes is huge.
Starter codeC++
1#include <cstddef>2#include <cstdint>3 4class BumpAllocator {5public:6    void* allocate(size_t bytes, size_t alignment);7    void reset();8};