ZealOS/src/Kernel/Memory/MemPag.CC

U0 SysBadFree(I64 *ptr)
{
	Panic("Bad Free:", ptr);
}

U0 SysBadMAlloc(I64 *ptr)
{
	Panic("Bad MAlloc:", ptr);
}

U8 *MemPagAlloc(I64 pags, CBlkPool *bp=NULL)
{/*Alloc pags from BlkPool. Don't link to task.
(Linking to a task means they will be freed when the task dies.)
It might give you more than you asked for.

Return: NULL if out of memory.
*/
	CMemBlk	*res = NULL, *m;
	I64		 i;

	if (!bp)
		bp = sys_code_bp;

	PUSHFD
	CLI
	while (LBts(&bp->locked_flags, BPlf_LOCKED))
		PAUSE
	if (pags < MEM_FREE_PAG_HASH_SIZE)
	{
		if (res = bp->free_pag_hash[pags])
		{
			bp->free_pag_hash[pags] = res->next;
			goto at_done;
		}
		i = Bsr(MEM_FREE_PAG_HASH_SIZE) + 1;
	} else {
//We'll now round-up to a power of two.
		//There is some overhead on allocations and
		//we wouldn't want to round to the next
		//power of two if a power of two was requested.
		//So we use a little more than a power of two.
		pags -= MEM_EXTRA_HASH2_PAGS;
		i = Bsr(pags) + 1;
		pags = 1 << i + MEM_EXTRA_HASH2_PAGS;
		if (res = bp->free_pag_hash2[i])
		{
			bp->free_pag_hash2[i] = res->next;
			goto at_done;
		}
	}
	m = &bp->mem_free_list;
	while (TRUE)
	{
		if (!(res = m->next))
		{
//We're probably out of luck, but lets search for a
			//freed larger size block... and, screw-it, return the whole thing.
			do
			{
				if (res = bp->free_pag_hash2[++i])
				{
					pags = 1 << i + MEM_EXTRA_HASH2_PAGS;
					bp->free_pag_hash2[i] = res->next;
					goto at_done;
				}
			}
			while (i < 64 - MEM_PAG_BITS - 1);

			pags = 0;
			res = NULL; //Out of memory
			goto at_done2;
		}
		if (res->pags < pags)
			m = res;
		else
		{
			if (res->pags == pags)
			{
				m->next = res->next;
				goto at_done;
			}
			else
			{
				res->pags -= pags;
				res(U8 *) += res->pags << MEM_PAG_BITS;
				res->pags = pags;
				goto at_done;
			}
		}
	}
at_done:
	bp->used_u8s += res->pags << MEM_PAG_BITS;
at_done2:
	LBtr(&bp->locked_flags, BPlf_LOCKED);
	POPFD

	return res;
}

U0 MemPagFree(CMemBlk *m, CBlkPool *bp=NULL)
{//Return non-task pags to BlkPool.
	I64 i, pags;

	if (m)
	{
		if (!bp)
			bp = sys_code_bp;

		PUSHFD
		CLI
		while (LBts(&bp->locked_flags, BPlf_LOCKED))
			PAUSE
		pags = m->pags;
		m->mb_signature = MBS_UNUSED_SIGNATURE_VAL;
		bp->used_u8s -= pags << MEM_PAG_BITS;
		if (pags < MEM_FREE_PAG_HASH_SIZE)
		{
			m->next = bp->free_pag_hash[pags];
			bp->free_pag_hash[pags] = m;
		}
		else
		{
//We'll now round-up to a power of two.
			//There is some overhead on allocations and
			//we wouldn't want to round to the next
			//power of two if a power of two was requested.
			//So we use a little more than a power of two.
			pags -= MEM_EXTRA_HASH2_PAGS;
			i = Bsr(pags);
			m->next = bp->free_pag_hash2[i];
			bp->free_pag_hash2[i] = m;
		}
		LBtr(&bp->locked_flags, BPlf_LOCKED);
		POPFD
	}
}

CMemBlk *MemPagTaskAlloc(I64 pags, CHeapCtrl *hc)
{/*hc must be locked.  Don't preempt this routine.
Currently, this is only called from $LK,"MAlloc",A="MN:MAlloc"$().
Return: NULL if out of memory.
*/
	CMemBlk		*res;
	I64			 threshold, count, size;
	CMemUnused	*uum, **_uum, **_ptr;

	if (res = MemPagAlloc(pags, hc->bp))
	{
		QueueInsert(res, hc->last_mem_blk);
		res->mb_signature = MBS_USED_SIGNATURE_VAL;
		hc->alloced_u8s += res->pags << MEM_PAG_BITS;

		//Tidy-up free list (Move into heap hash)
		//because if free list gets long, delay causes crash.
		threshold = MEM_HEAP_HASH_SIZE >> 4;
#assert MEM_HEAP_HASH_SIZE >> 4 >= sizeof(U8 *)
		do
		{
			count = 0;
			_uum = &hc->malloc_free_list;
			while (uum = *_uum)
			{
#assert !offset(CMemUnused.next)
				size = uum->size;
				if (size < threshold)
				{
					*_uum = uum->next;
					_ptr = (&hc->heap_hash)(U8 *) + size;
					uum->next = *_ptr;
					*_ptr = uum;
				}
				else
				{
					count++;
					_uum = uum;
				}
			}
			threshold <<= 1;
		}
		while (count > 8 && threshold <= MEM_HEAP_HASH_SIZE);
	}
	return res;
}

U0 MemPagTaskFree(CMemBlk *m, CHeapCtrl *hc)
{//hc must be locked
	if (m)
	{
		PUSHFD
		CLI
		if (m->mb_signature != MBS_USED_SIGNATURE_VAL)
			SysBadFree(m);
		else
		{
			QueueRemove(m);
			hc->alloced_u8s -= m->pags << MEM_PAG_BITS;
			MemPagFree(m, hc->bp);
		}
		POPFD
	}
}