
Dynamic allocator:
Dynamic allocator keeps the heap as a group of several size blocks; each block is an attached portion of virtual memory which is allocated or free.
- An allocated block has been clearly kept for use by the application.
- A free block is offered to be allocated.
Two types of allocators:
- 1. Explicit allocators
- 2. Implicit allocators
Explicit allocators:
Explicit allocators need the application to explicitly free any allocated blocks.
Implicit allocators:
Implicit allocators is the method of automatically releasing vacant allocated blocks. This is also known as garbage collection.
Explicit free list:
In this method, a block contains one word header, payload and additional padding. The header encrypts the block size which contains header and padding; and also check the block is allocated or free.
- The heap can be organized doubly linked list by including predecessor and successor pointer in each free block.
- This method reduces the allocation time when compared to implicit free list.
- If the arrangement is single-word, the block size is constantly a multiple of “4” and the low-order bits of the block size are always zero.
- If the arrangement is double-word, the block size is constantly a multiple of “8” and the low-order bits of the block size are always zero.

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