zynaddsubfx

tlsf.c (29751B)

---

 #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] & (~0U << sl);
 	if (!sl_map)
 	{
 		/* No block exists. Search in the next largest first-level list. */
 		const unsigned int fl_map = control->fl_bitmap & (~0U << (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 && !block->size)
 			block = NULL;
 
 	}
 
 	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)
 {
     (void) used;
 	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;
 }