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Reformat & cleanup

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This commit is contained in:
Nils O. Selåsdal
2026-04-19 04:22:23 +02:00
parent 64a5b20941
commit aba9cba602
2 changed files with 62 additions and 71 deletions
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include/ucore/spool.h
+2 -6
View File
@@ -10,7 +10,7 @@ extern "C" {
typedef union UCPoolBlock UCPoolBlock;
union UCPoolBlock {
UCPoolBlock *next; // next free block (when not allocated)
unsigned char data[]; // data when allocated
unsigned char data[0]; // data when allocated
};
/** @file
* Static pool allocator.
@@ -45,11 +45,7 @@ struct UCPool {
* @param block_size size of each allocation.
* @param alignment alignment of each block (must be power of 2)
*/
void uc_pool_init(UCPool *pool,
void *buffer,
size_t buffer_size,
size_t block_size,
size_t alignment);
void uc_pool_init(UCPool *pool, void *buffer, size_t buffer_size, size_t block_size, size_t alignment);
// Allocate a block from the pool. Returns NULL if no more space
[[gnu::assume_aligned(_Alignof(UCPoolBlock))]]
src/small_allocator.c
+35 -40
View File
@@ -15,28 +15,21 @@
* fragmentation to a minimum
*/
#define ALIGNMENT 16
#define ALIGN_UP(n) (((n) + (ALIGNMENT - 1)) & ~(ALIGNMENT - 1))
#define ALIGN_DOWN(n) ((n) & ~(ALIGNMENT - 1))
#define NULL_BLOCK (0xffffffff)
#define BLOCK_FREE ((uint32_t)1)
typedef struct BlockHeader {
uint32_t next; // offset from base
uint32_t prev; // offset from base
uint32_t size_and_flags; // size | free_bit
// Padding to ensure we always return 16 byte aligned pointers.
// Remove padding & set ALIGNMENT to 8 to get 8 byte alignmet
// (for 64 bit systems, 32 bit systems might need other adjustments)
uint8_t pad[4];
} BlockHeader;
#define ALIGNMENT sizeof(BlockHeader)
#define ALIGN_UP(n) (((n) + (ALIGNMENT - 1)) & ~(ALIGNMENT - 1))
#define ALIGN_DOWN(n) ((n) & ~(ALIGNMENT - 1))
_Static_assert(sizeof(BlockHeader) % ALIGNMENT == 0,
"BlockHeader size must be a multiple of ALIGNMENT");
#define NULL_BLOCK (0xffffffff)
#define BLOCK_FREE ((uint32_t)1)
_Static_assert(ALIGNMENT == 16, "sizeof(BlockHeader) is not 16");
typedef struct {
uint8_t* base; // backing store
@@ -47,12 +40,12 @@ typedef struct {
/* --- Header helpers --- */
static inline uint32_t block_size(BlockHeader* b)
static inline uint32_t block_size(const BlockHeader* b)
{
return b->size_and_flags & ~BLOCK_FREE;
}
static inline int block_is_free(BlockHeader* b)
static inline int block_is_free(const BlockHeader* b)
{
return (b->size_and_flags & BLOCK_FREE) != 0;
}
@@ -67,14 +60,13 @@ static inline void block_set_used(BlockHeader* b)
b->size_and_flags &= ~BLOCK_FREE;
}
static inline void block_set_size(BlockHeader* b, uint32_t size)
{
uint32_t flags = b->size_and_flags & BLOCK_FREE;
b->size_and_flags = size | flags;
}
static inline BlockHeader * bh_from_offset(const SmallAllocator *a, uint32_t off)
static inline BlockHeader* block_from_offset(const SmallAllocator* a, uint32_t off)
{
if (off == NULL_BLOCK) {
return NULL;
@@ -113,17 +105,15 @@ void small_allocator_init(SmallAllocator* a, void* backing_store, uint32_t size)
a->last_alloc = first;
}
static void split_block(SmallAllocator *a, BlockHeader* block, uint32_t size)
static void maybe_split_block(SmallAllocator* a, BlockHeader* block, uint32_t size)
{
size = ALIGN_UP(size);
// assumes size is already aligned
uint32_t bsize = block_size(block);
if (bsize < size + sizeof(BlockHeader) + ALIGNMENT)
return;
if (bsize < size + sizeof(BlockHeader) + ALIGNMENT) return;
uint8_t* base = (uint8_t*)block;
BlockHeader* new_block =
(BlockHeader*)(base + sizeof(BlockHeader) + size);
BlockHeader* new_block = (BlockHeader*)(base + sizeof(BlockHeader) + size);
uint32_t new_size = ALIGN_UP(bsize - size - sizeof(BlockHeader));
@@ -134,10 +124,9 @@ static void split_block(SmallAllocator *a, BlockHeader* block, uint32_t size)
new_block->next = block->next;
new_block->prev = bh_offset(a, block);
BlockHeader *next = bh_from_offset(a, new_block->next);
BlockHeader* next = block_from_offset(a, new_block->next);
if (next) {
next->prev = bh_offset(a, new_block);
//block->next->prev = new_block;
}
block->next = bh_offset(a, new_block);
@@ -145,19 +134,15 @@ static void split_block(SmallAllocator *a, BlockHeader* block, uint32_t size)
static void merge_with_next(SmallAllocator* a, BlockHeader* block)
{
BlockHeader* next = bh_from_offset(a, block->next);
if (!next || !block_is_free(next))
return;
BlockHeader* next = block_from_offset(a, block->next);
if (next == NULL || !block_is_free(next)) return;
uint32_t new_size = ALIGN_UP(block_size(block) +
sizeof(BlockHeader) +
block_size(next));
uint32_t new_size = ALIGN_UP(block_size(block) + sizeof(BlockHeader) + block_size(next));
block_set_size(block, new_size);
block->next = next->next;
BlockHeader *nextnext = bh_from_offset(a, next->next);
if (nextnext)
nextnext->prev = bh_offset(a, block);
BlockHeader* nextnext = block_from_offset(a, next->next);
if (nextnext) nextnext->prev = bh_offset(a, block);
}
void* small_alloc(SmallAllocator* a, uint32_t size)
@@ -169,12 +154,12 @@ void* small_alloc(SmallAllocator* a, uint32_t size)
do {
if (block_is_free(curr) && block_size(curr) >= size) {
split_block(a, curr, size);
maybe_split_block(a, curr, size);
block_set_used(curr);
a->last_alloc = curr;
return (uint8_t*)curr + sizeof(BlockHeader);
}
curr = bh_from_offset(a, curr->next) ? bh_from_offset(a, curr->next) : a->heap_start;
curr = block_from_offset(a, curr->next) ? block_from_offset(a, curr->next) : a->heap_start;
} while (curr != start);
return NULL;
@@ -197,7 +182,7 @@ void small_free(SmallAllocator* a, void* ptr)
block_set_free(block);
merge_with_next(a, block);
BlockHeader* prev = bh_from_offset(a, block->prev);
BlockHeader* prev = block_from_offset(a, block->prev);
if (prev != NULL && block_is_free(prev)) {
merge_with_next(a, prev);
@@ -215,13 +200,13 @@ void small_free(SmallAllocator* a, void* ptr)
void debug_alloc(const SmallAllocator* a)
{
puts("--debug start--");
for (BlockHeader *b = a->heap_start ; b ; b = bh_from_offset(a, b->next)) {
for (BlockHeader* b = a->heap_start; b; b = block_from_offset(a, b->next)) {
printf("Block size %u free %d prev %u next %u \n", block_size(b), block_is_free(b), b->prev, b->next);
}
puts("--debug end--");
}
char buff[1023*1023];
[[gnu::aligned(16)]] char buff[1023 * 1023];
int main(void)
{
printf("bh size %zu\n", sizeof(BlockHeader));
@@ -230,9 +215,19 @@ int main(void)
char* ptrs[SZ];
small_allocator_init(&a, buff, sizeof buff);
ptrs[0] = small_alloc(&a, 16);
debug_alloc(&a);
ptrs[0] = small_alloc(&a, 32);
ptrs[1] = small_alloc(&a, 80);
ptrs[2] = small_alloc(&a, 32);
small_free(&a, ptrs[1]);
ptrs[3] = small_alloc(&a, 12);
ptrs[4] = small_alloc(&a, 12);
debug_alloc(&a);
small_free(&a, ptrs[0]);
small_free(&a, ptrs[2]);
small_free(&a, ptrs[3]);
small_free(&a, ptrs[4]);
for (int i = 0; i < SZ; i++) {
ptrs[i] = small_alloc(&a, rand() % 256 + 1);