hmem

hmem - heap memory experiments

Quick Start

$ make test

Notes

• user pointer: is a pointer which allocator returns with heap_alloc function.
• sys pointer: is a pointer which points to data segment internals.

Development Steps

1. Created heap components; data segment, object (freed, allocated) segments. Freed and allocated object segments was responsible of storing user pointer (which returned with heap_alloc function) and requested memory size in their structure.
2. Introduced meta arena in data segment. While allocating memory, allocator creates additional meta arena before user which stores requested memory size in it ([sys_pointer + user_pointer]). This approach helped to;
   • remove redundant size information in object (freed, allocated) segments
   • change object segments to store only sys pointers
   • switch between user and sys pointers with simple pointer arithmetics.

Tests

• test_zero_allocation: Tests zero sized allocation does not changes anything on heap.
• test_alphabet_allocation: Tests allocation and writing of English alphabet through custom heap.
• test_continuous_allocation: Tests continuous allocation. Allocates memory with size 1 byte to 10 bytes, and free heap.
• test_memory_gap: Like test_continuous_allocation but creates gap by freeing even sized memories.
• test_free_space_compaction_by_prev: Allocates to memory space (p0,p1), and frees p0 then p1 to test free space compaction.
• test_free_space_compaction_by_next: Allocates to memory space (p0,p1), and frees p1 then p0 to test free space compaction.
• test_free_space_compaction: Test case is like test_memory_gap. Additionally frees 3th pointer/memory space, to check 2nd and 4th is merged with 3th pointer/memory space.

Plans

• TBD

References

• TBD