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SALLOC

Static memory allocator.

Original idea by Sergey Shevchuk (Nachos836);

Implementation by Taras Maliukh (Iipal);

General Idea

Header-only library with malloc-like behavior for mapping\allocation memory on static buffer, so all work with memory mostly can be optimized and calculated at compile-time.

Internal

More details of everything documented in code.

Code logic based on this document, which explains everything about most common malloc-like allocator implementations. Details:

  • Implemented using implicit bidirectional free-list aka Bidirectional Coalescing: Boundary Tags.
  • Each allocation takes additional 16bytes in the static buffer for Boundary Tags info.
    • In code, each Boundary Tag is described in the __s_tag_t structure
  • Each allocation aligned by 16bytes by default. (24 will align to 32)
  • Each allocation will use Best Fit method to find a free block. Best Fit: Search the list, choose the best free block: fits, with the fewest bytes leftover.
  • On sfree call implemented with Bidirectional Coalescing with preceding free blocks.
  • Optional nullability checks (_Nonnull and _Nullable) with SALLOC_NULLABILITY.
  • All code formatted via clang-format (version 12.0).
  • No dependency on any library, even on standard libc.
    • NOTE: If you define SALLOC_DEBUG before salloc.h include then it's will include also stdio.h and salloc_trace will use printf.

Originally it's written for clang only, because of its features.

All macroses, types or functions with prefixes: __s_, __st_, __s2c, __sattr_, __salloc_ or __sfree_ are created only for internal-use purposes.