arena.c: Arena creation, reservation, traversal, and destruction.arena-alloc.c: Allocation, freeing, commitment, and purging of arena slices.arena-page.c: Allocation, abandonment, reclamation, and freeing of pages backed by arena slices.arena.h: Private arena declarations, traversal callbacks, and layout helpers.bitmap.c: Concurrent bitmap searches and range operations; these bitmaps are used to manage the slices in an arena.bitmap-chunk.c: Bitmaps consist of 512-bit chunks; this provides the low-level atomic bit-field and bitmap-chunk operations.bitmap.h: Bitmap types, constants, and operation declarations.bitmap-chunk.h: Private declarations and iteration helpers for bitmap fields and chunks.