// k_heap_compress - Merge free blocks
// This function "compresses" the linked list, consolidating as many adjacent free blocks as possible, to reduce fragmentation.
int k_heap_compress() {
k_heap_blk* blk = heap.start;
k_heap_blk* next = NULL;
int blks_deleted = 0;
__dynmem_lock.lock_cli();
while((blk != NULL) && (blk->next != NULL)) { // Don't compress the first or last block in the heap.
next = blk->next;
if(blk->prev != NULL) {
if(!blk->used && !blk->prev->used) { // If both the current block and the one before it are free...
// ...then _delete_ this block.
k_heap_delete(blk);
blks_deleted++;
}
}
blk = next;
}
if((heap.end->prev != NULL) && (!heap.end->prev->used)) {
k_heap_delete(heap.end);
blks_deleted++;
}
__dynmem_lock.unlock_cli();
return blks_deleted;
}
// k_heap_add_at_offset - Add a new heap block
// This function places a new heap block in memory, linked to an "origin" block.
void k_heap_add_at_offset(k_heap_blk* origin_blk, int block_offset) {
__dynmem_lock.lock_cli();
k_heap_blk* blk = (k_heap_blk*)((size_t)origin_blk+(block_offset*HEAP_BLK_SIZE));
blk->prev = origin_blk;
blk->next = origin_blk->next;
blk->magic = HEAP_MAGIC_NUMBER;
blk->prev->next = blk;
if(blk->next != NULL)
blk->next->prev = blk;
else
heap.end = blk;
__dynmem_lock.unlock_cli();
}
// k_heap_delete - Unlink a block
// This function removes a block from the linked list, effectively "deleting" it.
void k_heap_delete(k_heap_blk* blk) {
__dynmem_lock.lock_cli();
if(blk == NULL) {
panic("dynmem: Attempted to delete NULL block!");
}
if(blk->prev != NULL) {
blk->prev->next = blk->next;
} else {
return; // can't delete the first block
}
if(blk->next != NULL) {
blk->next->prev = blk->prev;
} else {
heap.end = blk->prev;
}
blk->next = NULL;
blk->prev = NULL;
blk->magic = 0;
blk->used = false;
__dynmem_lock.unlock_cli();
}
