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Diffstat (limited to 'README.md')
| -rw-r--r-- | README.md | 20 |
1 files changed, 14 insertions, 6 deletions
@@ -4,7 +4,7 @@ Tiny replacement for `malloc` / `free` in unmanaged, linear memory situations, e ## Features -- written in C11, no dependencies or syscalls +- written in standalone C11, no dependencies, C runtime or syscalls used - configurable address region (and max. block count) for heap space - configurable pointer alignment in heap space - optional compaction of consecutive free blocks @@ -13,11 +13,13 @@ Tiny replacement for `malloc` / `free` in unmanaged, linear memory situations, e ## Details -**tinyalloc** maintains 3 linked lists: available blocks, used blocks, free blocks. All lists are stored in the same fixed sized array, so the memory overhead can be controlled at compile time via the [configuration vars](#configuration) listed below. During initialization all blocks are added to the list of available blocks. +**tinyalloc** maintains 3 linked lists: fresh blocks, used blocks, free blocks. All lists are stored in the same fixed sized array so the memory overhead can be controlled at compile time via the [configuration vars](#configuration) listed below. During initialization all blocks are added to the list of available blocks. + + ### Allocation -When a new chunk of memory is requested, all previously freed blocks are checked for potential re-use. If a block is found and larger than the requested size and the size difference is greater than the configured threshold (`TA_SPLIT_THRESHOLD`), the existing block is first split, the chunks are added to the used & free lists respectively and the pointer to the first chunk returned to the user. If no blocks in the free list qualify, a new block is allocated at the current heap top address, moved from the "available" to the "used" block list and the pointer returned to the caller. +When a new chunk of memory is requested, all previously freed blocks are checked for potential re-use. If a block is found, is larger than the requested size and the size difference is greater than the configured threshold (`TA_SPLIT_THRESHOLD`), then the block is first split, the chunks added to the used & free lists respectively and the pointer to the first chunk returned to the user. If no blocks in the free list qualify, a new block is allocated at the current heap top address, moved from the "fresh" to the "used" block list and the pointer returned to the caller. Note: All returned pointers are aligned to `TA_ALIGN` word boundaries. Same goes for allocated block sizes. @@ -55,17 +57,23 @@ Structural validation. Returns `true` if internal heap structure is ok. |--------|---------|---------| | `TA_ALIGN` | 8 | Word size for pointer alignment | | `TA_BASE` | 0x400 | Address of **tinyalloc** control data structure | +| `TA_DEBUG` | undefined | Trace debug information | | `TA_HEAP_START` | 0x1010 | Heap space start address | -| `TA_HEAP_LIMIT` | 0x1000000 | Heap space end address | +| `TA_HEAP_LIMIT` | 0xffffff | Heap space end address | | `TA_HEAP_BLOCKS` | 256 | Max. number of memory chunks | -| `TA_SPLIT_THRESHOLD` | 16 | Size threshold for splitting chunks | +| `TA_SPLIT_THRESH` | 16 | Size threshold for splitting chunks | + +On a 32bit system, the default configuration causes an overhead of 3088 bytes in RAM, but can be reduced if fewer memory blocks are needed. **Notes:** - `TA_ALIGN` is assumed to be >= native word size - `TA_HEAP_START` is assumed to be properly aligned -On a 32bit system, the default configuration causes an overhead of 3088 bytes in RAM, but can be reduced if fewer memory blocks are needed. +If building in debug mode (if `TA_DEBUG` symbol is defined), two externally defined functions are required: + +- `print_s(char *)` - to print a single string +- `print_i(size_t)` - to print a single unsigned int ### Building for WASM |