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Diffstat (limited to 'common/tlsf.c')
| -rw-r--r-- | common/tlsf.c | 961 |
1 files changed, 961 insertions, 0 deletions
diff --git a/common/tlsf.c b/common/tlsf.c new file mode 100644 index 0000000000..02dc8d44a8 --- /dev/null +++ b/common/tlsf.c @@ -0,0 +1,961 @@ +#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 pool structure. */ +typedef struct pool_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]; +} pool_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(pool_t* pool, 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 = pool->sl_bitmap[fl] & (~0 << sl); + if (!sl_map) + { + /* No block exists. Search in the next largest first-level list. */ + const unsigned int fl_map = pool->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 = pool->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 pool->blocks[fl][sl]; +} + +/* Remove a free block from the free list.*/ +static void remove_free_block(pool_t* pool, 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 (pool->blocks[fl][sl] == block) + { + pool->blocks[fl][sl] = next; + + /* If the new head is null, clear the bitmap. */ + if (next == &pool->block_null) + { + pool->sl_bitmap[fl] &= ~(1 << sl); + + /* If the second bitmap is now empty, clear the fl bitmap. */ + if (!pool->sl_bitmap[fl]) + { + pool->fl_bitmap &= ~(1 << fl); + } + } + } +} + +/* Insert a free block into the free block list. */ +static void insert_free_block(pool_t* pool, block_header_t* block, int fl, int sl) +{ + block_header_t* current = pool->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 = &pool->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. + */ + pool->blocks[fl][sl] = block; + pool->fl_bitmap |= (1 << fl); + pool->sl_bitmap[fl] |= (1 << sl); +} + +/* Remove a given block from the free list. */ +static void block_remove(pool_t* pool, block_header_t* block) +{ + int fl, sl; + mapping_insert(block_size(block), &fl, &sl); + remove_free_block(pool, block, fl, sl); +} + +/* Insert a given block into the free list. */ +static void block_insert(pool_t* pool, block_header_t* block) +{ + int fl, sl; + mapping_insert(block_size(block), &fl, &sl); + insert_free_block(pool, 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(pool_t* pool, 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(pool, 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(pool_t* pool, 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(pool, 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(pool_t* pool, 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(pool, remaining_block); + } +} + +/* Trim any trailing block space off the end of a used block, return to pool. */ +static void block_trim_used(pool_t* pool, 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(pool, remaining_block); + block_insert(pool, remaining_block); + } +} + +static block_header_t* block_trim_free_leading(pool_t* pool, 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(pool, block); + } + + return remaining_block; +} + +static block_header_t* block_locate_free(pool_t* pool, size_t size) +{ + int fl = 0, sl = 0; + block_header_t* block = 0; + + if (size) + { + mapping_search(size, &fl, &sl); + block = search_suitable_block(pool, &fl, &sl); + } + + if (block) + { + tlsf_assert(block_size(block) >= size); + remove_free_block(pool, block, fl, sl); + } + + return block; +} + +static void* block_prepare_used(pool_t* pool, block_header_t* block, size_t size) +{ + void* p = 0; + if (block) + { + block_trim_free(pool, 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 pool_construct(pool_t* pool) +{ + int i, j; + + pool->block_null.next_free = &pool->block_null; + pool->block_null.prev_free = &pool->block_null; + + pool->fl_bitmap = 0; + for (i = 0; i < FL_INDEX_COUNT; ++i) + { + pool->sl_bitmap[i] = 0; + for (j = 0; j < SL_INDEX_COUNT; ++j) + { + pool->blocks[i][j] = &pool->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_heap(tlsf_pool tlsf) +{ + int i, j; + + pool_t* pool = tlsf_cast(pool_t*, tlsf); + int status = 0; + + /* Check that the blocks are physically correct. */ + integrity_t integ = { 0, 0 }; + tlsf_walk_heap(tlsf, integrity_walker, &integ); + status = integ.status; + + /* 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 = pool->fl_bitmap & (1 << i); + const int sl_list = pool->sl_bitmap[i]; + const int sl_map = sl_list & (1 << j); + const block_header_t* block = pool->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 == &pool->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 != &pool->block_null && "block should not be null"); + + while (block != &pool->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_heap(tlsf_pool pool, tlsf_walker walker, void* user) +{ + tlsf_walker heap_walker = walker ? walker : default_walker; + block_header_t* block = + offset_to_block(pool, sizeof(pool_t) - block_header_overhead); + + while (block && !block_is_last(block)) + { + heap_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; +} + +/* +** Overhead of the TLSF structures in a given memory block passed to +** tlsf_create, equal to the size of a pool_t plus overhead of the initial +** free block and the sentinel block. +*/ +size_t tlsf_overhead() +{ + const size_t pool_overhead = sizeof(pool_t) + 2 * block_header_overhead; + return pool_overhead; +} + +/* +** TLSF main interface. Right out of the white paper. +*/ + +tlsf_pool tlsf_create(void* mem, size_t bytes) +{ + block_header_t* block; + block_header_t* next; + + const size_t pool_overhead = tlsf_overhead(); + const size_t pool_bytes = align_down(bytes - pool_overhead, ALIGN_SIZE); + pool_t* pool = tlsf_cast(pool_t*, mem); + +#if _DEBUG + /* 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; + if (rv) + { + printf("tlsf_create: %x ffs/fls tests failed!\n", rv); + return 0; + } +#endif +#endif + + if (pool_bytes < block_size_min || pool_bytes > block_size_max) + { +#if defined (TLSF_64BIT) + printf("tlsf_create: Pool size must be at least %d bytes.\n", + (unsigned int)(pool_overhead + block_size_min)); +#else + printf("tlsf_create: Pool 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; + } + + /* Construct a valid pool object. */ + pool_construct(pool); + + /* + ** Create the main free block. Offset the start of the block slightly + ** so that the prev_phys_block field falls inside of the pool + ** structure - it will never be used. + */ + block = offset_to_block( + tlsf_cast(void*, pool), sizeof(pool_t) - block_header_overhead); + block_set_size(block, pool_bytes); + block_set_free(block); + block_set_prev_used(block); + block_insert(pool, block); + + /* Split the block to create a zero-size pool sentinel block. */ + next = block_link_next(block); + block_set_size(next, 0); + block_set_used(next); + block_set_prev_free(next); + + return tlsf_cast(tlsf_pool, pool); +} + +void tlsf_destroy(tlsf_pool pool) +{ + /* Nothing to do. */ + pool = pool; +} + +void* tlsf_malloc(tlsf_pool tlsf, size_t size) +{ + pool_t* pool = tlsf_cast(pool_t*, tlsf); + const size_t adjust = adjust_request_size(size, ALIGN_SIZE); + block_header_t* block = block_locate_free(pool, adjust); + return block_prepare_used(pool, block, adjust); +} + +void* tlsf_memalign(tlsf_pool tlsf, size_t align, size_t size) +{ + pool_t* pool = tlsf_cast(pool_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 heap. 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(pool, 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(pool, block, gap); + } + } + + return block_prepare_used(pool, block, adjust); +} + +void tlsf_free(tlsf_pool tlsf, void* ptr) +{ + /* Don't attempt to free a NULL pointer. */ + if (ptr) + { + pool_t* pool = tlsf_cast(pool_t*, tlsf); + block_header_t* block = block_from_ptr(ptr); + block_mark_as_free(block); + block = block_merge_prev(pool, block); + block = block_merge_next(pool, block); + block_insert(pool, 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_pool tlsf, void* ptr, size_t size) +{ + pool_t* pool = tlsf_cast(pool_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); + + /* + ** 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(pool, block); + block_mark_as_used(block); + } + + /* Trim the resulting block and return the original pointer. */ + block_trim_used(pool, block, adjust); + p = ptr; + } + } + + return p; +} |