Files
my-os-project2/ulib/umalloc/umalloc.c
2025-09-28 19:55:37 +02:00

122 lines
2.5 KiB
C

#include <stdint.h>
#include <stddef.h>
#include <umalloc/umalloc.h>
#include <sysdefs/mman.h>
#include <system/system.h>
#include <errors.h>
#include <linklist.h>
#include <string/string.h>
#include <write/write.h>
#include <util/util.h>
#include <assert.h>
#define ARENA_SIZE (1<<20)
#define BLOCK_MAGIC 0xDEADBEEF
typedef struct UmArena {
struct UmArena *next;
uintptr_t mem;
uintptr_t base;
size_t cursor;
int64_t balance;
} __attribute__((aligned(16))) UmArena;
typedef struct {
uint32_t magic;
size_t size;
uint8_t data[];
} __attribute__((aligned(16))) UmBlock;
static UmArena *ARENAS = NULL;
UmArena *um_newarena(void) {
size_t arenasize = ARENA_SIZE;
uint8_t *mem = NULL;
int32_t err = mman_map(NULL, arenasize, MMAN_MAP_PF_RW, 0, &mem);
if (mem == NULL || err != E_OK) {
return NULL;
}
UmArena *arena = (UmArena *)mem;
arena->base = (uintptr_t)mem;
arena->mem = ((uintptr_t)mem + sizeof(UmArena) + 15) & ~0xF;
arena->cursor = 0;
arena->balance = 0;
LL_APPEND(ARENAS, arena);
return arena;
}
void *umalloc(size_t size) {
UmArena *usable = NULL;
size = (size + 15) & ~(size_t)0xF;
UmArena *arena, *arenatmp;
LL_FOREACH_SAFE(ARENAS, arena, arenatmp) {
if (arena->cursor + sizeof(UmBlock) + size <= ARENA_SIZE - ((uintptr_t)arena->mem - arena->base)) {
usable = arena;
break;
}
}
if (usable == NULL) {
usable = um_newarena();
}
if (usable == NULL) {
return NULL;
}
uintptr_t addr = usable->mem + usable->cursor;
UmBlock *block = (UmBlock *)addr;
block->size = size;
block->magic = BLOCK_MAGIC;
usable->cursor += sizeof(UmBlock) + size;
usable->balance += size;
string_memset(block->data, 0, size);
return block->data;
}
void ufree(void *ptr_) {
if (ptr_ == NULL) {
return;
}
uintptr_t ptr = (uintptr_t)ptr_;
UmArena *freeable = NULL;
size_t size = 0;
UmArena *arena, *arenatmp;
LL_FOREACH_SAFE(ARENAS, arena, arenatmp) {
if (ptr >= arena->mem && ptr < arena->mem + arena->cursor) {
UmBlock *block = (UmBlock *)(ptr - sizeof(UmBlock));
if (((uintptr_t)block->data != ptr)
|| (block->magic != BLOCK_MAGIC)
|| (block->size == 0)
|| (block->size > ARENA_SIZE)) {
return;
}
string_memset(block->data, 0xDD, block->size);
block->magic = 0;
arena->balance -= block->size;
ASSERT(arena->balance >= 0, "umalloc: imbalance after free\n");
if (arena->balance == 0) {
LL_REMOVE(ARENAS, arena);
mman_unmap((void *)arena->base);
}
return;
}
}
}