In main.cpp, there is a test for the feature of this heap memory manager.

This project implements my own "malloc()/free()" and "new/delete" on heap memory. It includes two kinds of memory allocators.

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General memory allocator (to allocate custom sized memory for user)：

• Use Doubly linked list to manage allocated and unallocated memory blocks

• Suballocate from end of the heap memory.

• Subtract needed size (i_size) from end of heap memory to get enough memory for user.

• Round down to aligned address.

• aligned address ⇒ end of block = user memory.

• Create new MemoryBlock for user memory.

• Have a working block collection function that looks through the list of unallocated memory blocks, combining any that can be into a single larger unallocated block.

 

Fixed size memory allocator (to allocate small fixed size memory for user)：

• Benefits:

  • Doesn’t require a fit search when making an allocation of that size.

  • No internal fragmentation.

  • Reduces per-alloc overhead.

  • In real game development, most memory allocations have small fixed size.

• Use BitArray (with bitwise operator) to manage allocated and unallocated memory blocks (one bit, 1 for in use, 0 for not).

• Use the compiler intrinsics _BitScanForward() and _BitScanForward64() to help find the first set bit or unset bit to locate the needed memory block.