mem: introducing TLSF malloc

TLSF is a real-time oriented dynamic allocator, with O(1) malloc() and free() costs

mem/Readme.tlsf.txt

@@ -0,0 +1,102 @@
+Two Level Segregated Fit memory allocator implementation.
+Written by Matthew Conte ([email protected]).
+Public Domain, no restrictions.
+
+	http://tlsf.baisoku.org
+
+Features
+--------
+* O(1) cost for malloc, free, realloc, memalign
+* Extremely low overhead per allocation (4 bytes)
+* Low overhead per TLSF management of pools (~3kB)
+* Low fragmentation
+* Compiles to only a few kB of code and data
+* Support for adding and removing memory pool regions on the fly
+
+Caveats
+-------
+* Currently, assumes architecture can make 4-byte aligned accesses
+* Not designed to be thread safe; the user must provide this
+
+Notes
+-----
+This code was based on the TLSF 1.4 spec and documentation found at:
+
+	http://rtportal.upv.es/rtmalloc/allocators/tlsf/index.shtml
+
+It also leverages the TLSF 2.0 improvement to shrink the per-block overhead
+from 8 to 4 bytes.
+
+Known Issues
+------------
+* Due to the internal block structure size and the implementation
+details of tlsf_memalign, there is worst-case behavior when requesting
+small (<16 byte) blocks aligned to 8-byte boundaries. Overuse of memalign
+will generally increase fragmentation, but this particular case will leave
+lots of unusable "holes" in the pool. The solution would be to internally
+align all blocks to 8 bytes, but this will require significantl changes
+to the implementation. Contact me if you are interested.
+
+History
+-------
+2014/02/08 - v3.0
+   * This version is based on improvements from 3DInteractive GmbH
+   * Interface changed to allow more than one memory pool
+   * Separated pool handling from control structure (adding, removing, debugging)
+   * Control structure and pools can still be constructed in the same memory block
+   * Memory blocks for control structure and pools are checked for alignment
+   * Added functions to retrieve control structure size, alignment size, min and
+     max block size, overhead of pool structure, and overhead of a single allocation
+   * Minimal Pool size is tlsf_block_size_min() + tlsf_pool_overhead()
+   * Pool must be empty when it is removed, in order to allow O(1) removal
+
+2011/10/20 - v2.0
+   * 64-bit support
+   * More compiler intrinsics for ffs/fls
+   * ffs/fls verification during TLSF creation in debug builds
+
+2008/04/04 - v1.9
+   * Add tlsf_heap_check, a heap integrity check
+   * Support a predefined tlsf_assert macro
+   * Fix realloc case where block should shrink; if adjacent block is
+     in use, execution would go down the slow path
+
+2007/02/08 - v1.8
+   * Fix for unnecessary reallocation in tlsf_realloc
+
+2007/02/03 - v1.7
+   * tlsf_heap_walk takes a callback
+   * tlsf_realloc now returns NULL on failure
+   * tlsf_memalign optimization for 4-byte alignment
+   * Usage of size_t where appropriate
+
+2006/11/21 - v1.6
+   * ffs/fls broken out into tlsfbits.h
+   * tlsf_overhead queries per-pool overhead
+
+2006/11/07 - v1.5
+   * Smart realloc implementation
+   * Smart memalign implementation
+
+2006/10/11 - v1.4
+   * Add some ffs/fls implementations
+   * Minor code footprint reduction
+
+2006/09/14 - v1.3
+   * Profiling indicates heavy use of blocks of
+     size 1-128, so implement small block handling
+   * Reduce pool overhead by about 1kb
+   * Reduce minimum block size from 32 to 12 bytes
+   * Realloc bug fix
+
+2006/09/09 - v1.2
+   * Add tlsf_block_size
+   * Static assertion mechanism for invariants
+   * Minor bugfixes 
+
+2006/09/01 - v1.1
+   * Add tlsf_realloc
+   * Add tlsf_walk_heap
+
+2006/08/25 - v1.0
+   * First release

mem/tlsf.c

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+#include <assert.h>
+#include <limits.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "tlsf.h"
+#include "tlsfbits.h"
+
+/*
+** Constants.
+*/
+
+/* Public constants: may be modified. */
+enum tlsf_public
+{
+	/* log2 of number of linear subdivisions of block sizes. */
+	SL_INDEX_COUNT_LOG2 = 5,
+};
+
+/* Private constants: do not modify. */
+enum tlsf_private
+{
+#if defined (TLSF_64BIT)
+	/* All allocation sizes and addresses are aligned to 8 bytes. */
+	ALIGN_SIZE_LOG2 = 3,
+#else
+	/* All allocation sizes and addresses are aligned to 4 bytes. */
+	ALIGN_SIZE_LOG2 = 2,
+#endif
+	ALIGN_SIZE = (1 << ALIGN_SIZE_LOG2),
+
+	/*
+	** We support allocations of sizes up to (1 << FL_INDEX_MAX) bits.
+	** However, because we linearly subdivide the second-level lists, and
+	** our minimum size granularity is 4 bytes, it doesn't make sense to
+	** create first-level lists for sizes smaller than SL_INDEX_COUNT * 4,
+	** or (1 << (SL_INDEX_COUNT_LOG2 + 2)) bytes, as there we will be
+	** trying to split size ranges into more slots than we have available.
+	** Instead, we calculate the minimum threshold size, and place all
+	** blocks below that size into the 0th first-level list.
+	*/
+
+#if defined (TLSF_64BIT)
+	/*
+	** TODO: We can increase this to support larger sizes, at the expense
+	** of more overhead in the TLSF structure.
+	*/
+	FL_INDEX_MAX = 32,
+#else
+	FL_INDEX_MAX = 30,
+#endif
+	SL_INDEX_COUNT = (1 << SL_INDEX_COUNT_LOG2),
+	FL_INDEX_SHIFT = (SL_INDEX_COUNT_LOG2 + ALIGN_SIZE_LOG2),
+	FL_INDEX_COUNT = (FL_INDEX_MAX - FL_INDEX_SHIFT + 1),
+
+	SMALL_BLOCK_SIZE = (1 << FL_INDEX_SHIFT),
+};
+
+/*
+** Cast and min/max macros.
+*/
+
+#define tlsf_cast(t, exp)	((t) (exp))
+#define tlsf_min(a, b)		((a) < (b) ? (a) : (b))
+#define tlsf_max(a, b)		((a) > (b) ? (a) : (b))
+
+/*
+** Set assert macro, if it has not been provided by the user.
+*/
+#if !defined (tlsf_assert)
+#define tlsf_assert assert
+#endif
+
+/*
+** Static assertion mechanism.
+*/
+
+#define _tlsf_glue2(x, y) x ## y
+#define _tlsf_glue(x, y) _tlsf_glue2(x, y)
+#define tlsf_static_assert(exp) \
+	typedef char _tlsf_glue(static_assert, __LINE__) [(exp) ? 1 : -1]
+
+/* This code has been tested on 32- and 64-bit (LP/LLP) architectures. */
+tlsf_static_assert(sizeof(int) * CHAR_BIT == 32);
+tlsf_static_assert(sizeof(size_t) * CHAR_BIT >= 32);
+tlsf_static_assert(sizeof(size_t) * CHAR_BIT <= 64);
+
+/* SL_INDEX_COUNT must be <= number of bits in sl_bitmap's storage type. */
+tlsf_static_assert(sizeof(unsigned int) * CHAR_BIT >= SL_INDEX_COUNT);
+
+/* Ensure we've properly tuned our sizes. */
+tlsf_static_assert(ALIGN_SIZE == SMALL_BLOCK_SIZE / SL_INDEX_COUNT);
+
+/*
+** Data structures and associated constants.
+*/
+
+/*
+** Block header structure.
+**
+** There are several implementation subtleties involved:
+** - The prev_phys_block field is only valid if the previous block is free.
+** - The prev_phys_block field is actually stored at the end of the
+**   previous block. It appears at the beginning of this structure only to
+**   simplify the implementation.
+** - The next_free / prev_free fields are only valid if the block is free.
+*/
+typedef struct block_header_t
+{
+	/* Points to the previous physical block. */
+	struct block_header_t* prev_phys_block;
+
+	/* The size of this block, excluding the block header. */
+	size_t size;
+
+	/* Next and previous free blocks. */
+	struct block_header_t* next_free;
+	struct block_header_t* prev_free;
+} block_header_t;
+
+/*
+** Since block sizes are always at least a multiple of 4, the two least
+** significant bits of the size field are used to store the block status:
+** - bit 0: whether block is busy or free
+** - bit 1: whether previous block is busy or free
+*/
+static const size_t block_header_free_bit = 1 << 0;
+static const size_t block_header_prev_free_bit = 1 << 1;
+
+/*
+** The size of the block header exposed to used blocks is the size field.
+** The prev_phys_block field is stored *inside* the previous free block.
+*/
+static const size_t block_header_overhead = sizeof(size_t);
+
+/* User data starts directly after the size field in a used block. */
+static const size_t block_start_offset =
+	offsetof(block_header_t, size) + sizeof(size_t);
+
+/*
+** A free block must be large enough to store its header minus the size of
+** the prev_phys_block field, and no larger than the number of addressable
+** bits for FL_INDEX.
+*/
+static const size_t block_size_min = 
+	sizeof(block_header_t) - sizeof(block_header_t*);
+static const size_t block_size_max = tlsf_cast(size_t, 1) << FL_INDEX_MAX;
+
+
+/* The TLSF control structure. */
+typedef struct control_t
+{
+	/* Empty lists point at this block to indicate they are free. */
+	block_header_t block_null;
+
+	/* Bitmaps for free lists. */
+	unsigned int fl_bitmap;
+	unsigned int sl_bitmap[FL_INDEX_COUNT];
+
+	/* Head of free lists. */
+	block_header_t* blocks[FL_INDEX_COUNT][SL_INDEX_COUNT];
+} control_t;
+
+/* A type used for casting when doing pointer arithmetic. */
+typedef ptrdiff_t tlsfptr_t;
+
+/*
+** block_header_t member functions.
+*/
+
+static size_t block_size(const block_header_t* block)
+{
+	return block->size & ~(block_header_free_bit | block_header_prev_free_bit);
+}
+
+static void block_set_size(block_header_t* block, size_t size)
+{
+	const size_t oldsize = block->size;
+	block->size = size | (oldsize & (block_header_free_bit | block_header_prev_free_bit));
+}
+
+static int block_is_last(const block_header_t* block)
+{
+	return 0 == block_size(block);
+}
+
+static int block_is_free(const block_header_t* block)
+{
+	return tlsf_cast(int, block->size & block_header_free_bit);
+}
+
+static void block_set_free(block_header_t* block)
+{
+	block->size |= block_header_free_bit;
+}
+
+static void block_set_used(block_header_t* block)
+{
+	block->size &= ~block_header_free_bit;
+}
+
+static int block_is_prev_free(const block_header_t* block)
+{
+	return tlsf_cast(int, block->size & block_header_prev_free_bit);
+}
+
+static void block_set_prev_free(block_header_t* block)
+{
+	block->size |= block_header_prev_free_bit;
+}
+
+static void block_set_prev_used(block_header_t* block)
+{
+	block->size &= ~block_header_prev_free_bit;
+}
+
+static block_header_t* block_from_ptr(const void* ptr)
+{
+	return tlsf_cast(block_header_t*,
+		tlsf_cast(unsigned char*, ptr) - block_start_offset);
+}
+
+static void* block_to_ptr(const block_header_t* block)
+{
+	return tlsf_cast(void*,
+		tlsf_cast(unsigned char*, block) + block_start_offset);
+}
+
+/* Return location of next block after block of given size. */
+static block_header_t* offset_to_block(const void* ptr, size_t size)
+{
+	return tlsf_cast(block_header_t*, tlsf_cast(tlsfptr_t, ptr) + size);
+}
+
+/* Return location of previous block. */
+static block_header_t* block_prev(const block_header_t* block)
+{
+	return block->prev_phys_block;
+}
+
+/* Return location of next existing block. */
+static block_header_t* block_next(const block_header_t* block)
+{
+	block_header_t* next = offset_to_block(block_to_ptr(block),
+		block_size(block) - block_header_overhead);
+	tlsf_assert(!block_is_last(block));
+	return next;
+}
+
+/* Link a new block with its physical neighbor, return the neighbor. */
+static block_header_t* block_link_next(block_header_t* block)
+{
+	block_header_t* next = block_next(block);
+	next->prev_phys_block = block;
+	return next;
+}
+
+static void block_mark_as_free(block_header_t* block)
+{
+	/* Link the block to the next block, first. */
+	block_header_t* next = block_link_next(block);
+	block_set_prev_free(next);
+	block_set_free(block);
+}
+
+static void block_mark_as_used(block_header_t* block)
+{
+	block_header_t* next = block_next(block);
+	block_set_prev_used(next);
+	block_set_used(block);
+}
+
+static size_t align_up(size_t x, size_t align)
+{
+	tlsf_assert(0 == (align & (align - 1)) && "must align to a power of two");
+	return (x + (align - 1)) & ~(align - 1);
+}
+
+static size_t align_down(size_t x, size_t align)
+{
+	tlsf_assert(0 == (align & (align - 1)) && "must align to a power of two");
+	return x - (x & (align - 1));
+}
+
+static void* align_ptr(const void* ptr, size_t align)
+{
+	const tlsfptr_t aligned =
+		(tlsf_cast(tlsfptr_t, ptr) + (align - 1)) & ~(align - 1);
+	tlsf_assert(0 == (align & (align - 1)) && "must align to a power of two");
+	return tlsf_cast(void*, aligned);
+}
+
+/*
+** Adjust an allocation size to be aligned to word size, and no smaller
+** than internal minimum.
+*/
+static size_t adjust_request_size(size_t size, size_t align)
+{
+	size_t adjust = 0;
+	if (size && size < block_size_max)
+	{
+		const size_t aligned = align_up(size, align);
+		adjust = tlsf_max(aligned, block_size_min);
+	}
+	return adjust;
+}
+
+/*
+** TLSF utility functions. In most cases, these are direct translations of
+** the documentation found in the white paper.
+*/
+
+static void mapping_insert(size_t size, int* fli, int* sli)
+{
+	int fl, sl;
+	if (size < SMALL_BLOCK_SIZE)
+	{
+		/* Store small blocks in first list. */
+		fl = 0;
+		sl = tlsf_cast(int, size) / (SMALL_BLOCK_SIZE / SL_INDEX_COUNT);
+	}
+	else
+	{
+		fl = tlsf_fls_sizet(size);
+		sl = tlsf_cast(int, size >> (fl - SL_INDEX_COUNT_LOG2)) ^ (1 << SL_INDEX_COUNT_LOG2);
+		fl -= (FL_INDEX_SHIFT - 1);
+	}
+	*fli = fl;
+	*sli = sl;
+}
+
+/* This version rounds up to the next block size (for allocations) */
+static void mapping_search(size_t size, int* fli, int* sli)
+{
+	if (size >= (1 << SL_INDEX_COUNT_LOG2))
+	{
+		const size_t round = (1 << (tlsf_fls_sizet(size) - SL_INDEX_COUNT_LOG2)) - 1;
+		size += round;
+	}
+	mapping_insert(size, fli, sli);
+}
+
+static block_header_t* search_suitable_block(control_t* control, int* fli, int* sli)
+{
+	int fl = *fli;
+	int sl = *sli;
+
+	/*
+	** First, search for a block in the list associated with the given
+	** fl/sl index.
+	*/
+	unsigned int sl_map = control->sl_bitmap[fl] & (~0 << sl);
+	if (!sl_map)
+	{
+		/* No block exists. Search in the next largest first-level list. */
+		const unsigned int fl_map = control->fl_bitmap & (~0 << (fl + 1));
+		if (!fl_map)
+		{
+			/* No free blocks available, memory has been exhausted. */
+			return 0;
+		}
+
+		fl = tlsf_ffs(fl_map);
+		*fli = fl;
+		sl_map = control->sl_bitmap[fl];
+	}
+	tlsf_assert(sl_map && "internal error - second level bitmap is null");
+	sl = tlsf_ffs(sl_map);
+	*sli = sl;
+
+	/* Return the first block in the free list. */
+	return control->blocks[fl][sl];
+}
+
+/* Remove a free block from the free list.*/
+static void remove_free_block(control_t* control, block_header_t* block, int fl, int sl)
+{
+	block_header_t* prev = block->prev_free;
+	block_header_t* next = block->next_free;
+	tlsf_assert(prev && "prev_free field can not be null");
+	tlsf_assert(next && "next_free field can not be null");
+	next->prev_free = prev;
+	prev->next_free = next;
+
+	/* If this block is the head of the free list, set new head. */
+	if (control->blocks[fl][sl] == block)
+	{
+		control->blocks[fl][sl] = next;
+
+		/* If the new head is null, clear the bitmap. */
+		if (next == &control->block_null)
+		{
+			control->sl_bitmap[fl] &= ~(1 << sl);
+
+			/* If the second bitmap is now empty, clear the fl bitmap. */
+			if (!control->sl_bitmap[fl])
+			{
+				control->fl_bitmap &= ~(1 << fl);
+			}
+		}
+	}
+}
+
+/* Insert a free block into the free block list. */
+static void insert_free_block(control_t* control, block_header_t* block, int fl, int sl)
+{
+	block_header_t* current = control->blocks[fl][sl];
+	tlsf_assert(current && "free list cannot have a null entry");
+	tlsf_assert(block && "cannot insert a null entry into the free list");
+	block->next_free = current;
+	block->prev_free = &control->block_null;
+	current->prev_free = block;
+
+	tlsf_assert(block_to_ptr(block) == align_ptr(block_to_ptr(block), ALIGN_SIZE)
+		&& "block not aligned properly");
+	/*
+	** Insert the new block at the head of the list, and mark the first-
+	** and second-level bitmaps appropriately.
+	*/
+	control->blocks[fl][sl] = block;
+	control->fl_bitmap |= (1 << fl);
+	control->sl_bitmap[fl] |= (1 << sl);
+}
+
+/* Remove a given block from the free list. */
+static void block_remove(control_t* control, block_header_t* block)
+{
+	int fl, sl;
+	mapping_insert(block_size(block), &fl, &sl);
+	remove_free_block(control, block, fl, sl);
+}
+
+/* Insert a given block into the free list. */
+static void block_insert(control_t* control, block_header_t* block)
+{
+	int fl, sl;
+	mapping_insert(block_size(block), &fl, &sl);
+	insert_free_block(control, block, fl, sl);
+}
+
+static int block_can_split(block_header_t* block, size_t size)
+{
+	return block_size(block) >= sizeof(block_header_t) + size;
+}
+
+/* Split a block into two, the second of which is free. */
+static block_header_t* block_split(block_header_t* block, size_t size)
+{
+	/* Calculate the amount of space left in the remaining block. */
+	block_header_t* remaining =
+		offset_to_block(block_to_ptr(block), size - block_header_overhead);
+
+	const size_t remain_size = block_size(block) - (size + block_header_overhead);
+
+	tlsf_assert(block_to_ptr(remaining) == align_ptr(block_to_ptr(remaining), ALIGN_SIZE)
+		&& "remaining block not aligned properly");
+
+	tlsf_assert(block_size(block) == remain_size + size + block_header_overhead);
+	block_set_size(remaining, remain_size);
+	tlsf_assert(block_size(remaining) >= block_size_min && "block split with invalid size");
+
+	block_set_size(block, size);
+	block_mark_as_free(remaining);
+
+	return remaining;
+}
+
+/* Absorb a free block's storage into an adjacent previous free block. */
+static block_header_t* block_absorb(block_header_t* prev, block_header_t* block)
+{
+	tlsf_assert(!block_is_last(prev) && "previous block can't be last!");
+	/* Note: Leaves flags untouched. */
+	prev->size += block_size(block) + block_header_overhead;
+	block_link_next(prev);
+	return prev;
+}
+
+/* Merge a just-freed block with an adjacent previous free block. */
+static block_header_t* block_merge_prev(control_t* control, block_header_t* block)
+{
+	if (block_is_prev_free(block))
+	{
+		block_header_t* prev = block_prev(block);
+		tlsf_assert(prev && "prev physical block can't be null");
+		tlsf_assert(block_is_free(prev) && "prev block is not free though marked as such");
+		block_remove(control, prev);
+		block = block_absorb(prev, block);
+	}
+
+	return block;
+}
+
+/* Merge a just-freed block with an adjacent free block. */
+static block_header_t* block_merge_next(control_t* control, block_header_t* block)
+{
+	block_header_t* next = block_next(block);
+	tlsf_assert(next && "next physical block can't be null");
+
+	if (block_is_free(next))
+	{
+		tlsf_assert(!block_is_last(block) && "previous block can't be last!");
+		block_remove(control, next);
+		block = block_absorb(block, next);
+	}
+
+	return block;
+}
+
+/* Trim any trailing block space off the end of a block, return to pool. */
+static void block_trim_free(control_t* control, block_header_t* block, size_t size)
+{
+	tlsf_assert(block_is_free(block) && "block must be free");
+	if (block_can_split(block, size))
+	{
+		block_header_t* remaining_block = block_split(block, size);
+		block_link_next(block);
+		block_set_prev_free(remaining_block);
+		block_insert(control, remaining_block);
+	}
+}
+
+/* Trim any trailing block space off the end of a used block, return to pool. */
+static void block_trim_used(control_t* control, block_header_t* block, size_t size)
+{
+	tlsf_assert(!block_is_free(block) && "block must be used");
+	if (block_can_split(block, size))
+	{
+		/* If the next block is free, we must coalesce. */
+		block_header_t* remaining_block = block_split(block, size);
+		block_set_prev_used(remaining_block);
+
+		remaining_block = block_merge_next(control, remaining_block);
+		block_insert(control, remaining_block);
+	}
+}
+
+static block_header_t* block_trim_free_leading(control_t* control, block_header_t* block, size_t size)
+{
+	block_header_t* remaining_block = block;
+	if (block_can_split(block, size))
+	{
+		/* We want the 2nd block. */
+		remaining_block = block_split(block, size - block_header_overhead);
+		block_set_prev_free(remaining_block);
+
+		block_link_next(block);
+		block_insert(control, block);
+	}
+
+	return remaining_block;
+}
+
+static block_header_t* block_locate_free(control_t* control, size_t size)
+{
+	int fl = 0, sl = 0;
+	block_header_t* block = 0;
+
+	if (size)
+	{
+		mapping_search(size, &fl, &sl);
+		block = search_suitable_block(control, &fl, &sl);
+	}
+
+	if (block)
+	{
+		tlsf_assert(block_size(block) >= size);
+		remove_free_block(control, block, fl, sl);
+	}
+
+	return block;
+}
+
+static void* block_prepare_used(control_t* control, block_header_t* block, size_t size)
+{
+	void* p = 0;
+	if (block)
+	{
+		block_trim_free(control, block, size);
+		block_mark_as_used(block);
+		p = block_to_ptr(block);
+	}
+	return p;
+}
+
+/* Clear structure and point all empty lists at the null block. */
+static void control_construct(control_t* control)
+{
+	int i, j;
+
+	control->block_null.next_free = &control->block_null;
+	control->block_null.prev_free = &control->block_null;
+
+	control->fl_bitmap = 0;
+	for (i = 0; i < FL_INDEX_COUNT; ++i)
+	{
+		control->sl_bitmap[i] = 0;
+		for (j = 0; j < SL_INDEX_COUNT; ++j)
+		{
+			control->blocks[i][j] = &control->block_null;
+		}
+	}
+}
+
+/*
+** Debugging utilities.
+*/
+
+typedef struct integrity_t
+{
+	int prev_status;
+	int status;
+} integrity_t;
+
+#define tlsf_insist(x) { tlsf_assert(x); if (!(x)) { status--; } }
+
+static void integrity_walker(void* ptr, size_t size, int used, void* user)
+{
+	block_header_t* block = block_from_ptr(ptr);
+	integrity_t* integ = tlsf_cast(integrity_t*, user);
+	const int this_prev_status = block_is_prev_free(block) ? 1 : 0;
+	const int this_status = block_is_free(block) ? 1 : 0;
+	const size_t this_block_size = block_size(block);
+
+	int status = 0;
+	tlsf_insist(integ->prev_status == this_prev_status && "prev status incorrect");
+	tlsf_insist(size == this_block_size && "block size incorrect");
+
+	integ->prev_status = this_status;
+	integ->status += status;
+}
+
+int tlsf_check(tlsf_t tlsf)
+{
+	int i, j;
+
+	control_t* control = tlsf_cast(control_t*, tlsf);
+	int status = 0;
+
+	/* Check that the free lists and bitmaps are accurate. */
+	for (i = 0; i < FL_INDEX_COUNT; ++i)
+	{
+		for (j = 0; j < SL_INDEX_COUNT; ++j)
+		{
+			const int fl_map = control->fl_bitmap & (1 << i);
+			const int sl_list = control->sl_bitmap[i];
+			const int sl_map = sl_list & (1 << j);
+			const block_header_t* block = control->blocks[i][j];
+
+			/* Check that first- and second-level lists agree. */
+			if (!fl_map)
+			{
+				tlsf_insist(!sl_map && "second-level map must be null");
+			}
+
+			if (!sl_map)
+			{
+				tlsf_insist(block == &control->block_null && "block list must be null");
+				continue;
+			}
+
+			/* Check that there is at least one free block. */
+			tlsf_insist(sl_list && "no free blocks in second-level map");
+			tlsf_insist(block != &control->block_null && "block should not be null");
+
+			while (block != &control->block_null)
+			{
+				int fli, sli;
+				tlsf_insist(block_is_free(block) && "block should be free");
+				tlsf_insist(!block_is_prev_free(block) && "blocks should have coalesced");
+				tlsf_insist(!block_is_free(block_next(block)) && "blocks should have coalesced");
+				tlsf_insist(block_is_prev_free(block_next(block)) && "block should be free");
+				tlsf_insist(block_size(block) >= block_size_min && "block not minimum size");
+
+				mapping_insert(block_size(block), &fli, &sli);
+				tlsf_insist(fli == i && sli == j && "block size indexed in wrong list");
+				block = block->next_free;
+			}
+		}
+	}
+
+	return status;
+}
+
+#undef tlsf_insist
+
+static void default_walker(void* ptr, size_t size, int used, void* user)
+{
+	(void)user;
+	printf("\t%p %s size: %x (%p)\n", ptr, used ? "used" : "free", (unsigned int)size, block_from_ptr(ptr));
+}
+
+void tlsf_walk_pool(pool_t pool, tlsf_walker walker, void* user)
+{
+	tlsf_walker pool_walker = walker ? walker : default_walker;
+	block_header_t* block =
+		offset_to_block(pool, -(int)block_header_overhead);
+
+	while (block && !block_is_last(block))
+	{
+		pool_walker(
+			block_to_ptr(block),
+			block_size(block),
+			!block_is_free(block),
+			user);
+		block = block_next(block);
+	}
+}
+
+size_t tlsf_block_size(void* ptr)
+{
+	size_t size = 0;
+	if (ptr)
+	{
+		const block_header_t* block = block_from_ptr(ptr);
+		size = block_size(block);
+	}
+	return size;
+}
+
+int tlsf_check_pool(pool_t pool)
+{
+	/* Check that the blocks are physically correct. */
+	integrity_t integ = { 0, 0 };
+	tlsf_walk_pool(pool, integrity_walker, &integ);
+
+	return integ.status;
+}
+
+/*
+** Size of the TLSF structures in a given memory block passed to
+** tlsf_create, equal to the size of a control_t
+*/
+size_t tlsf_size()
+{
+	return sizeof(control_t);
+}
+
+size_t tlsf_align_size()
+{
+	return ALIGN_SIZE;
+}
+
+size_t tlsf_block_size_min()
+{
+	return block_size_min;
+}
+
+size_t tlsf_block_size_max()
+{
+	return block_size_max;
+}
+
+/*
+** Overhead of the TLSF structures in a given memory block passes to
+** tlsf_add_pool, equal to the overhead of a free block and the
+** sentinel block.
+*/
+size_t tlsf_pool_overhead()
+{
+	return 2 * block_header_overhead;
+}
+
+size_t tlsf_alloc_overhead()
+{
+	return block_header_overhead;
+}
+
+pool_t tlsf_add_pool(tlsf_t tlsf, void* mem, size_t bytes)
+{
+	block_header_t* block;
+	block_header_t* next;
+
+	const size_t pool_overhead = tlsf_pool_overhead();
+	const size_t pool_bytes = align_down(bytes - pool_overhead, ALIGN_SIZE);
+
+	if (((ptrdiff_t)mem % ALIGN_SIZE) != 0)
+	{
+		printf("tlsf_add_pool: Memory must be aligned by %u bytes.\n",
+			(unsigned int)ALIGN_SIZE);
+		return 0;
+	}
+
+	if (pool_bytes < block_size_min || pool_bytes > block_size_max)
+	{
+#if defined (TLSF_64BIT)
+		printf("tlsf_add_pool: Memory size must be between 0x%x and 0x%x00 bytes.\n", 
+			(unsigned int)(pool_overhead + block_size_min),
+			(unsigned int)((pool_overhead + block_size_max) / 256));
+#else
+		printf("tlsf_add_pool: Memory size must be between %u and %u bytes.\n", 
+			(unsigned int)(pool_overhead + block_size_min),
+			(unsigned int)(pool_overhead + block_size_max));
+#endif
+		return 0;
+	}
+
+	/*
+	** Create the main free block. Offset the start of the block slightly
+	** so that the prev_phys_block field falls outside of the pool -
+	** it will never be used.
+	*/
+	block = offset_to_block(mem, -(tlsfptr_t)block_header_overhead);
+	block_set_size(block, pool_bytes);
+	block_set_free(block);
+	block_set_prev_used(block);
+	block_insert(tlsf_cast(control_t*, tlsf), block);
+
+	/* Split the block to create a zero-size sentinel block. */
+	next = block_link_next(block);
+	block_set_size(next, 0);
+	block_set_used(next);
+	block_set_prev_free(next);
+
+	return mem;
+}
+
+void tlsf_remove_pool(tlsf_t tlsf, pool_t pool)
+{
+	control_t* control = tlsf_cast(control_t*, tlsf);
+	block_header_t* block = offset_to_block(pool, -(int)block_header_overhead);
+
+	int fl = 0, sl = 0;
+
+	tlsf_assert(block_is_free(block) && "block should be free");
+	tlsf_assert(!block_is_free(block_next(block)) && "next block should not be free");
+	tlsf_assert(block_size(block_next(block)) == 0 && "next block size should be zero");
+
+	mapping_insert(block_size(block), &fl, &sl);
+	remove_free_block(control, block, fl, sl);
+}
+
+/*
+** TLSF main interface.
+*/
+
+#if _DEBUG
+int test_ffs_fls()
+{
+	/* Verify ffs/fls work properly. */
+	int rv = 0;
+	rv += (tlsf_ffs(0) == -1) ? 0 : 0x1;
+	rv += (tlsf_fls(0) == -1) ? 0 : 0x2;
+	rv += (tlsf_ffs(1) == 0) ? 0 : 0x4;
+	rv += (tlsf_fls(1) == 0) ? 0 : 0x8;
+	rv += (tlsf_ffs(0x80000000) == 31) ? 0 : 0x10;
+	rv += (tlsf_ffs(0x80008000) == 15) ? 0 : 0x20;
+	rv += (tlsf_fls(0x80000008) == 31) ? 0 : 0x40;
+	rv += (tlsf_fls(0x7FFFFFFF) == 30) ? 0 : 0x80;
+
+#if defined (TLSF_64BIT)
+	rv += (tlsf_fls_sizet(0x80000000) == 31) ? 0 : 0x100;
+	rv += (tlsf_fls_sizet(0x100000000) == 32) ? 0 : 0x200;
+	rv += (tlsf_fls_sizet(0xffffffffffffffff) == 63) ? 0 : 0x400; 
+#endif
+
+	if (rv)
+	{
+		printf("tlsf_create: %x ffs/fls tests failed!\n", rv);
+	}
+	return rv;
+}
+#endif
+
+tlsf_t tlsf_create(void* mem)
+{
+#if _DEBUG
+	if (test_ffs_fls())
+	{
+		return 0;
+	}
+#endif
+
+	if (((tlsfptr_t)mem % ALIGN_SIZE) != 0)
+	{
+		printf("tlsf_create: Memory must be aligned to %u bytes.\n",
+			(unsigned int)ALIGN_SIZE);
+		return 0;
+	}
+
+	control_construct(tlsf_cast(control_t*, mem));
+
+	return tlsf_cast(tlsf_t, mem);
+}
+
+tlsf_t tlsf_create_with_pool(void* mem, size_t bytes)
+{
+	tlsf_t tlsf = tlsf_create(mem);
+	tlsf_add_pool(tlsf, (char*)mem + tlsf_size(), bytes - tlsf_size());
+	return tlsf;
+}
+
+void tlsf_destroy(tlsf_t tlsf)
+{
+	/* Nothing to do. */
+	(void)tlsf;
+}
+
+pool_t tlsf_get_pool(tlsf_t tlsf)
+{
+	return tlsf_cast(pool_t, (char*)tlsf + tlsf_size());
+}
+
+void* tlsf_malloc(tlsf_t tlsf, size_t size)
+{
+	control_t* control = tlsf_cast(control_t*, tlsf);
+	const size_t adjust = adjust_request_size(size, ALIGN_SIZE);
+	block_header_t* block = block_locate_free(control, adjust);
+	return block_prepare_used(control, block, adjust);
+}
+
+void* tlsf_memalign(tlsf_t tlsf, size_t align, size_t size)
+{
+	control_t* control = tlsf_cast(control_t*, tlsf);
+	const size_t adjust = adjust_request_size(size, ALIGN_SIZE);
+
+	/*
+	** We must allocate an additional minimum block size bytes so that if
+	** our free block will leave an alignment gap which is smaller, we can
+	** trim a leading free block and release it back to the pool. We must
+	** do this because the previous physical block is in use, therefore
+	** the prev_phys_block field is not valid, and we can't simply adjust
+	** the size of that block.
+	*/
+	const size_t gap_minimum = sizeof(block_header_t);
+	const size_t size_with_gap = adjust_request_size(adjust + align + gap_minimum, align);
+
+	/* If alignment is less than or equals base alignment, we're done. */
+	const size_t aligned_size = (align <= ALIGN_SIZE) ? adjust : size_with_gap;
+
+	block_header_t* block = block_locate_free(control, aligned_size);
+
+	/* This can't be a static assert. */
+	tlsf_assert(sizeof(block_header_t) == block_size_min + block_header_overhead);
+
+	if (block)
+	{
+		void* ptr = block_to_ptr(block);
+		void* aligned = align_ptr(ptr, align);
+		size_t gap = tlsf_cast(size_t,
+			tlsf_cast(tlsfptr_t, aligned) - tlsf_cast(tlsfptr_t, ptr));
+
+		/* If gap size is too small, offset to next aligned boundary. */
+		if (gap && gap < gap_minimum)
+		{
+			const size_t gap_remain = gap_minimum - gap;
+			const size_t offset = tlsf_max(gap_remain, align);
+			const void* next_aligned = tlsf_cast(void*,
+				tlsf_cast(tlsfptr_t, aligned) + offset);
+
+			aligned = align_ptr(next_aligned, align);
+			gap = tlsf_cast(size_t,
+				tlsf_cast(tlsfptr_t, aligned) - tlsf_cast(tlsfptr_t, ptr));
+		}
+
+		if (gap)
+		{
+			tlsf_assert(gap >= gap_minimum && "gap size too small");
+			block = block_trim_free_leading(control, block, gap);
+		}
+	}
+
+	return block_prepare_used(control, block, adjust);
+}
+
+void tlsf_free(tlsf_t tlsf, void* ptr)
+{
+	/* Don't attempt to free a NULL pointer. */
+	if (ptr)
+	{
+		control_t* control = tlsf_cast(control_t*, tlsf);
+		block_header_t* block = block_from_ptr(ptr);
+		tlsf_assert(!block_is_free(block) && "block already marked as free");
+		block_mark_as_free(block);
+		block = block_merge_prev(control, block);
+		block = block_merge_next(control, block);
+		block_insert(control, block);
+	}
+}
+
+/*
+** The TLSF block information provides us with enough information to
+** provide a reasonably intelligent implementation of realloc, growing or
+** shrinking the currently allocated block as required.
+**
+** This routine handles the somewhat esoteric edge cases of realloc:
+** - a non-zero size with a null pointer will behave like malloc
+** - a zero size with a non-null pointer will behave like free
+** - a request that cannot be satisfied will leave the original buffer
+**   untouched
+** - an extended buffer size will leave the newly-allocated area with
+**   contents undefined
+*/
+void* tlsf_realloc(tlsf_t tlsf, void* ptr, size_t size)
+{
+	control_t* control = tlsf_cast(control_t*, tlsf);
+	void* p = 0;
+
+	/* Zero-size requests are treated as free. */
+	if (ptr && size == 0)
+	{
+		tlsf_free(tlsf, ptr);
+	}
+	/* Requests with NULL pointers are treated as malloc. */
+	else if (!ptr)
+	{
+		p = tlsf_malloc(tlsf, size);
+	}
+	else
+	{
+		block_header_t* block = block_from_ptr(ptr);
+		block_header_t* next = block_next(block);
+
+		const size_t cursize = block_size(block);
+		const size_t combined = cursize + block_size(next) + block_header_overhead;
+		const size_t adjust = adjust_request_size(size, ALIGN_SIZE);
+
+		tlsf_assert(!block_is_free(block) && "block already marked as free");
+
+		/*
+		** If the next block is used, or when combined with the current
+		** block, does not offer enough space, we must reallocate and copy.
+		*/
+		if (adjust > cursize && (!block_is_free(next) || adjust > combined))
+		{
+			p = tlsf_malloc(tlsf, size);
+			if (p)
+			{
+				const size_t minsize = tlsf_min(cursize, size);
+				memcpy(p, ptr, minsize);
+				tlsf_free(tlsf, ptr);
+			}
+		}
+		else
+		{
+			/* Do we need to expand to the next block? */
+			if (adjust > cursize)
+			{
+				block_merge_next(control, block);
+				block_mark_as_used(block);
+			}
+
+			/* Trim the resulting block and return the original pointer. */
+			block_trim_used(control, block, adjust);
+			p = ptr;
+		}
+	}
+
+	return p;
+}

mem/tlsf.h

@@ -0,0 +1,68 @@
+#ifndef INCLUDED_tlsf
+#define INCLUDED_tlsf
+
+/*
+** Two Level Segregated Fit memory allocator, version 3.0.
+** Written by Matthew Conte, and placed in the Public Domain.
+**	http://tlsf.baisoku.org
+**
+** Based on the original documentation by Miguel Masmano:
+**	http://rtportal.upv.es/rtmalloc/allocators/tlsf/index.shtml
+**
+** Please see the accompanying Readme.txt for implementation
+** notes and caveats.
+**
+** This implementation was written to the specification
+** of the document, therefore no GPL restrictions apply.
+*/
+
+#include <stddef.h>
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+/* tlsf_t: a TLSF structure. Can contain 1 to N pools. */
+/* pool_t: a block of memory that TLSF can manage. */
+typedef void* tlsf_t;
+typedef void* pool_t;
+
+/* Create/destroy a memory pool. */
+tlsf_t tlsf_create(void* mem);
+tlsf_t tlsf_create_with_pool(void* mem, size_t bytes);
+void tlsf_destroy(tlsf_t tlsf);
+pool_t tlsf_get_pool(tlsf_t tlsf);
+
+/* Add/remove memory pools. */
+pool_t tlsf_add_pool(tlsf_t tlsf, void* mem, size_t bytes);
+void tlsf_remove_pool(tlsf_t tlsf, pool_t pool);
+
+/* malloc/memalign/realloc/free replacements. */
+void* tlsf_malloc(tlsf_t tlsf, size_t bytes);
+void* tlsf_memalign(tlsf_t tlsf, size_t align, size_t bytes);
+void* tlsf_realloc(tlsf_t tlsf, void* ptr, size_t size);
+void tlsf_free(tlsf_t tlsf, void* ptr);
+
+/* Returns internal block size, not original request size */
+size_t tlsf_block_size(void* ptr);
+
+/* Overheads/limits of internal structures. */
+size_t tlsf_size();
+size_t tlsf_align_size();
+size_t tlsf_block_size_min();
+size_t tlsf_block_size_max();
+size_t tlsf_pool_overhead();
+size_t tlsf_alloc_overhead();
+
+/* Debugging. */
+typedef void (*tlsf_walker)(void* ptr, size_t size, int used, void* user);
+void tlsf_walk_pool(pool_t pool, tlsf_walker walker, void* user);
+/* Returns nonzero if any internal consistency check fails. */
+int tlsf_check(tlsf_t tlsf);
+int tlsf_check_pool(pool_t pool);
+
+#if defined(__cplusplus)
+};
+#endif
+
+#endif

mem/tlsfbits.h

@@ -0,0 +1,180 @@
+#ifndef INCLUDED_tlsfbits
+#define INCLUDED_tlsfbits
+
+#if defined(__cplusplus)
+#define tlsf_decl inline
+#else
+#define tlsf_decl static
+#endif
+
+/*
+** Architecture-specific bit manipulation routines.
+**
+** TLSF achieves O(1) cost for malloc and free operations by limiting
+** the search for a free block to a free list of guaranteed size
+** adequate to fulfill the request, combined with efficient free list
+** queries using bitmasks and architecture-specific bit-manipulation
+** routines.
+**
+** Most modern processors provide instructions to count leading zeroes
+** in a word, find the lowest and highest set bit, etc. These
+** specific implementations will be used when available, falling back
+** to a reasonably efficient generic implementation.
+**
+** NOTE: TLSF spec relies on ffs/fls returning value 0..31.
+** ffs/fls return 1-32 by default, returning 0 for error.
+*/
+
+/*
+** Detect whether or not we are building for a 32- or 64-bit (LP/LLP)
+** architecture. There is no reliable portable method at compile-time.
+*/
+#if defined (__alpha__) || defined (__ia64__) || defined (__x86_64__) \
+	|| defined (_WIN64) || defined (__LP64__) || defined (__LLP64__)
+#define TLSF_64BIT
+#endif
+
+/*
+** gcc 3.4 and above have builtin support, specialized for architecture.
+** Some compilers masquerade as gcc; patchlevel test filters them out.
+*/
+#if defined (__GNUC__) && (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) \
+	&& defined (__GNUC_PATCHLEVEL__)
+
+tlsf_decl int tlsf_ffs(unsigned int word)
+{
+	return __builtin_ffs(word) - 1;
+}
+
+tlsf_decl int tlsf_fls(unsigned int word)
+{
+	const int bit = word ? 32 - __builtin_clz(word) : 0;
+	return bit - 1;
+}
+
+#elif defined (_MSC_VER) && (_MSC_VER >= 1400) && (defined (_M_IX86) || defined (_M_X64))
+/* Microsoft Visual C++ support on x86/X64 architectures. */
+
+#include <intrin.h>
+
+#pragma intrinsic(_BitScanReverse)
+#pragma intrinsic(_BitScanForward)
+
+tlsf_decl int tlsf_fls(unsigned int word)
+{
+	unsigned long index;
+	return _BitScanReverse(&index, word) ? index : -1;
+}
+
+tlsf_decl int tlsf_ffs(unsigned int word)
+{
+	unsigned long index;
+	return _BitScanForward(&index, word) ? index : -1;
+}
+
+#elif defined (_MSC_VER) && defined (_M_PPC)
+/* Microsoft Visual C++ support on PowerPC architectures. */
+
+#include <ppcintrinsics.h>
+
+tlsf_decl int tlsf_fls(unsigned int word)
+{
+	const int bit = 32 - _CountLeadingZeros(word);
+	return bit - 1;
+}
+
+tlsf_decl int tlsf_ffs(unsigned int word)
+{
+	const unsigned int reverse = word & (~word + 1);
+	const int bit = 32 - _CountLeadingZeros(reverse);
+	return bit - 1;
+}
+
+#elif defined (__ARMCC_VERSION)
+/* RealView Compilation Tools for ARM */
+
+tlsf_decl int tlsf_ffs(unsigned int word)
+{
+	const unsigned int reverse = word & (~word + 1);
+	const int bit = 32 - __clz(reverse);
+	return bit - 1;
+}
+
+tlsf_decl int tlsf_fls(unsigned int word)
+{
+	const int bit = word ? 32 - __clz(word) : 0;
+	return bit - 1;
+}
+
+#elif defined (__ghs__)
+/* Green Hills support for PowerPC */
+
+#include <ppc_ghs.h>
+
+tlsf_decl int tlsf_ffs(unsigned int word)
+{
+	const unsigned int reverse = word & (~word + 1);
+	const int bit = 32 - __CLZ32(reverse);
+	return bit - 1;
+}
+
+tlsf_decl int tlsf_fls(unsigned int word)
+{
+	const int bit = word ? 32 - __CLZ32(word) : 0;
+	return bit - 1;
+}
+
+#else
+/* Fall back to generic implementation. */
+
+tlsf_decl int tlsf_fls_generic(unsigned int word)
+{
+	int bit = 32;
+
+	if (!word) bit -= 1;
+	if (!(word & 0xffff0000)) { word <<= 16; bit -= 16; }
+	if (!(word & 0xff000000)) { word <<= 8; bit -= 8; }
+	if (!(word & 0xf0000000)) { word <<= 4; bit -= 4; }
+	if (!(word & 0xc0000000)) { word <<= 2; bit -= 2; }
+	if (!(word & 0x80000000)) { word <<= 1; bit -= 1; }
+
+	return bit;
+}
+
+/* Implement ffs in terms of fls. */
+tlsf_decl int tlsf_ffs(unsigned int word)
+{
+	return tlsf_fls_generic(word & (~word + 1)) - 1;
+}
+
+tlsf_decl int tlsf_fls(unsigned int word)
+{
+	return tlsf_fls_generic(word) - 1;
+}
+
+#endif
+
+/* Possibly 64-bit version of tlsf_fls. */
+#if defined (TLSF_64BIT)
+tlsf_decl int tlsf_fls_sizet(size_t size)
+{
+	int high = (int)(size >> 32);
+	int bits = 0;
+	if (high)
+	{
+		bits = 32 + tlsf_fls(high);
+	}
+	else
+	{
+		bits = tlsf_fls((int)size & 0xffffffff);
+
+	}
+	return bits;
+}
+#else
+#define tlsf_fls_sizet tlsf_fls
+#endif
+
+#undef tlsf_decl
+
+#endif