79 lines
2.0 KiB
C
79 lines
2.0 KiB
C
#include "malloc.h"
|
|
#include <stdbool.h>
|
|
#include <string.h>
|
|
#include <sys/mman.h>
|
|
|
|
// Fast allocator for sizes 16, 32, 48, 64 bytes
|
|
|
|
malloc_header_t* free_blocks[5];
|
|
|
|
void prepare_free_blocks(size_t size)
|
|
{
|
|
int block_id = size >> 4;
|
|
const size_t alloc_size = MALLOC_DEFAULT_BLOCK_SIZE;
|
|
intptr_t ret = (intptr_t)mmap(NULL, alloc_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
|
|
if (ret < 0) {
|
|
free_blocks[block_id] = NULL;
|
|
return;
|
|
}
|
|
|
|
void* raw_area = (void*)ret;
|
|
const size_t sizeof_block_with_header = size + sizeof(malloc_header_t);
|
|
size_t passed = 0;
|
|
|
|
free_blocks[block_id] = (malloc_header_t*)raw_area;
|
|
malloc_header_t* prev_header = NULL;
|
|
|
|
while (passed + sizeof_block_with_header <= alloc_size) {
|
|
malloc_header_t* current = (malloc_header_t*)raw_area;
|
|
|
|
current->flags = FLAG_SLAB | FLAG_ALLOCATED;
|
|
current->next = NULL;
|
|
current->prev = prev_header;
|
|
current->size = size;
|
|
|
|
prev_header = current;
|
|
raw_area += sizeof_block_with_header;
|
|
passed += sizeof_block_with_header;
|
|
}
|
|
|
|
malloc_header_t* next_header = NULL;
|
|
while (prev_header) {
|
|
prev_header->next = next_header;
|
|
prev_header = prev_header->prev;
|
|
}
|
|
}
|
|
|
|
void _slab_init()
|
|
{
|
|
prepare_free_blocks(16);
|
|
prepare_free_blocks(32);
|
|
prepare_free_blocks(48);
|
|
prepare_free_blocks(64);
|
|
}
|
|
|
|
void* slab_alloc(size_t size)
|
|
{
|
|
if (size > 64) {
|
|
return NULL;
|
|
}
|
|
int block_id = ((size + 15) >> 4);
|
|
malloc_header_t* zone = free_blocks[block_id];
|
|
if (!zone) {
|
|
return NULL;
|
|
}
|
|
|
|
free_blocks[block_id] = zone->next;
|
|
return (void*)&((malloc_header_t*)zone)[1];
|
|
}
|
|
|
|
void slab_free(malloc_header_t* mem_header)
|
|
{
|
|
malloc_header_t* next = free_blocks[((mem_header->size) >> 4)];
|
|
free_blocks[((mem_header->size) >> 4)] = mem_header;
|
|
mem_header->next = next;
|
|
mem_header->prev = NULL;
|
|
if (next) {
|
|
next->prev = mem_header;
|
|
}
|
|
} |