/*
** Two Level Segregated Fit memory allocator, version 3.1.
** Written by Matthew Conte
** http://tlsf.baisoku.org
**
** Based on the original documentation by Miguel Masmano:
** http://www.gii.upv.es/tlsf/main/docs
**
** This implementation was written to the specification
** of the document, therefore no GPL restrictions apply.
**
** Copyright (c) 2006-2016, Matthew Conte
** All rights reserved.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are met:
** * Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** * Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in the
** documentation and/or other materials provided with the distribution.
** * Neither the name of the copyright holder nor the
** names of its contributors may be used to endorse or promote products
** derived from this software without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
** WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
** DISCLAIMED. IN NO EVENT SHALL MATTHEW CONTE BE LIABLE FOR ANY
** DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
** (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
** SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "multi_heap_config.h"
#include "multi_heap.h"
#include "multi_heap_internal.h"
#include "heap_tlsf_config.h"
#include "heap_tlsf.h"
/*
** 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.
*/
static inline __attribute__((__always_inline__)) int tlsf_ffs(unsigned int word)
{
const unsigned int reverse = word & (~word + 1);
const int bit = 32 - __builtin_clz(reverse);
return bit - 1;
}
static inline __attribute__((__always_inline__)) int tlsf_fls(unsigned int word)
{
const int bit = word ? 32 - __builtin_clz(word) : 0;
return bit - 1;
}
/*
** 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);
static inline __attribute__((__always_inline__)) 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 inline __attribute__((__always_inline__)) 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 inline __attribute__((__always_inline__)) 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 inline __attribute__((__always_inline__)) size_t adjust_request_size(size_t size, size_t align)
{
size_t adjust = 0;
if (size)
{
const size_t aligned = align_up(size, align);
/* aligned sized must not exceed block_size_max or we'll go out of bounds on sl_bitmap */
if (aligned < block_size_max)
{
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 inline __attribute__((__always_inline__)) 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) >> 2;
}
else
{
fl = tlsf_fls(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 inline __attribute__((__always_inline__)) void mapping_search(size_t size, int* fli, int* sli)
{
if (size >= SMALL_BLOCK_SIZE)
{
const size_t round = (1 << (tlsf_fls(size) - SL_INDEX_COUNT_LOG2)) - 1;
size += round;
}
mapping_insert(size, fli, sli);
}
static inline __attribute__((__always_inline__)) 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 inline __attribute__((__always_inline__)) 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 inline __attribute__((__always_inline__)) 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 inline __attribute__((__always_inline__)) 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 inline __attribute__((__always_inline__)) 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 inline __attribute__((__always_inline__)) 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 inline __attribute__((__always_inline__)) block_header_t* block_split(block_header_t* block, size_t size)
{
/* Calculate the amount of space left in the remaining block.
* REMINDER: remaining pointer's first field is `prev_phys_block` but this field is part of the
* previous physical block. */
block_header_t* remaining =
offset_to_block(block_to_ptr(block), size - block_header_overhead);
/* `size` passed as an argument is the first block's new size, thus, the remaining block's size
* is `block_size(block) - size`. However, the block's data must be precedeed by the data size.
* This field is NOT part of the size, so it has to be substracted from the calculation. */
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);
/**
* Here is the final outcome of this function:
*
* block remaining (block_ptr + size - BHO)
* + +
* | |
* v v
* +----------------------------------------------------------------------+
* |0000| |xxxxxxxxxxxxxxxxxxxxxx|xxxx| |###########################|
* |0000| |xxxxxxxxxxxxxxxxxxxxxx|xxxx| |###########################|
* |0000| |xxxxxxxxxxxxxxxxxxxxxx|xxxx| |###########################|
* |0000| |xxxxxxxxxxxxxxxxxxxxxx|xxxx| |###########################|
* +----------------------------------------------------------------------+
* | | | |
* + +<------------------------->+ +<------------------------->
* BHO `size` (argument) bytes BHO `remain_size` bytes
*
* Where BHO = block_header_overhead,
* 0: part of the memory owned by a `block`'s previous neighbour,
* x: part of the memory owned by `block`.
* #: part of the memory owned by `remaining`.
*/
return remaining;
}
/* Absorb a free block's storage into an adjacent previous free block. */
static inline __attribute__((__always_inline__)) 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);
#ifdef MULTI_HEAP_POISONING_SLOW
/* next_block header needs to be replaced with a fill pattern */
multi_heap_internal_poison_fill_region(block, sizeof(block_header_t), true /* free */);
#endif
return prev;
}
/* Merge a just-freed block with an adjacent previous free block. */
static inline __attribute__((__always_inline__)) 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 inline __attribute__((__always_inline__)) 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 inline __attribute__((__always_inline__)) 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 inline __attribute__((__always_inline__)) 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 inline __attribute__((__always_inline__)) 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 to split `block` in two: the first block will be freed and the
* second block will be returned. */
remaining_block = block_split(block, size - block_header_overhead);
/* `remaining_block` is the second block, mark its predecessor (first
* block) as free. */
block_set_prev_free(remaining_block);
block_link_next(block);
/* Put back the first block into the free memory list. */
block_insert(control, block);
}
return remaining_block;
}
static inline __attribute__((__always_inline__)) 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);
/*
** mapping_search can futz with the size, so for excessively large sizes it can sometimes wind up
** with indices that are off the end of the block array.
** So, we protect against that here, since this is the only callsite of mapping_search.
** Note that we don't need to check sl, since it comes from a modulo operation that guarantees it's always in range.
*/
if (fl < FL_INDEX_COUNT)
{
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 inline __attribute__((__always_inline__)) void* block_prepare_used(control_t* control, block_header_t* block, size_t size)
{
void* p = 0;
if (block)
{
tlsf_assert(size && "size must be non-zero");
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;
(void)used;
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(void)
{
return sizeof(control_t);
}
size_t tlsf_align_size(void)
{
return ALIGN_SIZE;
}
size_t tlsf_block_size_min(void)
{
return block_size_min;
}
size_t tlsf_block_size_max(void)
{
return block_size_max;
}
/*
** Overhead of the TLSF structures in a given memory block passed to
** tlsf_add_pool, equal to the overhead of a free block and the
** sentinel block.
*/
size_t tlsf_pool_overhead(void)
{
return 2 * block_header_overhead;
}
size_t tlsf_alloc_overhead(void)
{
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.
*/
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);
}
pool_t tlsf_get_pool(tlsf_t tlsf)
{
return tlsf_cast(pool_t, (char*)tlsf + tlsf_size());
}
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_malloc(tlsf_t tlsf, size_t size)
{
control_t* control = tlsf_cast(control_t*, tlsf);
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);
}
/**
* @brief Allocate memory of at least `size` bytes where byte at `data_offset` will be aligned to `alignment`.
*
* This function will allocate memory pointed by `ptr`. However, the byte at `data_offset` of
* this piece of memory (i.e., byte at `ptr` + `data_offset`) will be aligned to `alignment`.
* This function is useful for allocating memory that will internally have a header, and the
* usable memory following the header (i.e. `ptr` + `data_offset`) must be aligned.
*
* For example, a call to `multi_heap_aligned_alloc_impl_offs(heap, 64, 256, 20)` will return a
* pointer `ptr` to free memory of minimum 64 bytes, where `ptr + 20` is aligned on `256`.
* So `(ptr + 20) % 256` equals 0.
*
* @param tlsf TLSF structure to allocate memory from.
* @param align Alignment for the returned pointer's offset.
* @param size Minimum size, in bytes, of the memory to allocate INCLUDING
* `data_offset` bytes.
* @param data_offset Offset to be aligned on `alignment`. This can be 0, in
* this case, the returned pointer will be aligned on
* `alignment`. If it is not a multiple of CPU word size,
* it will be aligned up to the closest multiple of it.
*
* @return pointer to free memory.
*/
void* tlsf_memalign_offs(tlsf_t tlsf, size_t align, size_t size, size_t data_offset)
{
control_t* control = tlsf_cast(control_t*, tlsf);
const size_t adjust = adjust_request_size(size, ALIGN_SIZE);
const size_t off_adjust = align_up(data_offset, 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) + off_adjust;
/* The offset is included in both `adjust` and `gap_minimum`, so we
** need to subtract it once.
*/
const size_t size_with_gap = adjust_request_size(adjust + align + gap_minimum - off_adjust, align);
/*
** If alignment is less than or equals base alignment, we're done.
** If we requested 0 bytes, return null, as tlsf_malloc(0) does.
*/
const size_t aligned_size = (adjust && align > ALIGN_SIZE) ? size_with_gap : adjust;
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 or if there is not gap but we need one,
** offset to next aligned boundary.
*/
if ((gap && gap < gap_minimum) || (!gap && off_adjust))
{
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 - off_adjust);
}
}
/* Preparing the block will also the trailing free memory. */
return block_prepare_used(control, block, adjust);
}
/**
* @brief Same as `tlsf_memalign_offs` function but with a 0 offset.
* The pointer returned is aligned on `align`.
*/
void* tlsf_memalign(tlsf_t tlsf, size_t align, size_t size)
{
return tlsf_memalign_offs(tlsf, align, size, 0);
}
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;
}