void mem_init(void)
{
struct free_arena_header *fp;
int i;
uint16_t *bios_free_mem = (uint16_t *)0x413;
/* Initialize the head nodes */
fp = &__malloc_head[0];
for (i = 0 ; i < NHEAP ; i++) {
fp->a.next = fp->a.prev = fp->next_free = fp->prev_free = fp;
fp->a.attrs = ARENA_TYPE_HEAD | (i << ARENA_HEAP_POS);
fp->a.tag = MALLOC_HEAD;
fp++;
}
/* Initialize the main heap */
fp = (struct free_arena_header *)main_heap;
fp->a.attrs = ARENA_TYPE_USED | (HEAP_MAIN << ARENA_HEAP_POS);
ARENA_SIZE_SET(fp->a.attrs, sizeof main_heap);
__inject_free_block(fp);
/* Initialize the lowmem heap */
fp = (struct free_arena_header *)__lowmem_heap;
fp->a.attrs = ARENA_TYPE_USED | (HEAP_LOWMEM << ARENA_HEAP_POS);
ARENA_SIZE_SET(fp->a.attrs, (*bios_free_mem << 10) - (uintptr_t)fp);
__inject_free_block(fp);
}
static struct free_arena_header *
__free_block(struct free_arena_header *ah)
{
struct free_arena_header *pah, *nah;
struct free_arena_header *head =
&__core_malloc_head[ARENA_HEAP_GET(ah->a.attrs)];
pah = ah->a.prev;
nah = ah->a.next;
if ( ARENA_TYPE_GET(pah->a.attrs) == ARENA_TYPE_FREE &&
(char *)pah+ARENA_SIZE_GET(pah->a.attrs) == (char *)ah ) {
/* Coalesce into the previous block */
ARENA_SIZE_SET(pah->a.attrs, ARENA_SIZE_GET(pah->a.attrs) +
ARENA_SIZE_GET(ah->a.attrs));
pah->a.next = nah;
nah->a.prev = pah;
#ifdef DEBUG_MALLOC
ARENA_TYPE_SET(ah->a.attrs, ARENA_TYPE_DEAD);
#endif
ah = pah;
pah = ah->a.prev;
} else {
/* Need to add this block to the free chain */
ARENA_TYPE_SET(ah->a.attrs, ARENA_TYPE_FREE);
ah->a.tag = MALLOC_FREE;
ah->next_free = head->next_free;
ah->prev_free = head;
head->next_free = ah;
ah->next_free->prev_free = ah;
}
/* In either of the previous cases, we might be able to merge
with the subsequent block... */
if ( ARENA_TYPE_GET(nah->a.attrs) == ARENA_TYPE_FREE &&
(char *)ah+ARENA_SIZE_GET(ah->a.attrs) == (char *)nah ) {
ARENA_SIZE_SET(ah->a.attrs, ARENA_SIZE_GET(ah->a.attrs) +
ARENA_SIZE_GET(nah->a.attrs));
/* Remove the old block from the chains */
nah->next_free->prev_free = nah->prev_free;
nah->prev_free->next_free = nah->next_free;
ah->a.next = nah->a.next;
nah->a.next->a.prev = ah;
#ifdef DEBUG_MALLOC
ARENA_TYPE_SET(nah->a.attrs, ARENA_TYPE_DEAD);
#endif
}
/* Return the block that contains the called block */
return ah;
}
