/******************************************************
Binary buddy allocator for compressed pages

(c) 2006 Innobase Oy

Created December 2006 by Marko Makela
*******************************************************/

#ifdef UNIV_MATERIALIZE
# undef UNIV_INLINE
# define UNIV_INLINE
#endif

#include "buf0buf.h"
#include "buf0buddy.h"
#include "ut0ut.h"
#ifdef UNIV_SYNC_DEBUG
# include "sync0sync.h"
#endif /* UNIV_SYNC_DEBUG */

/**************************************************************************
Allocate a block. */

void*
buf_buddy_alloc_low(
/*================*/
			/* out: pointer to the start of the block */
	ulint	i,	/* in: index of buf_pool->zip_free[] */
	ibool	lru)	/* in: TRUE=allocate from the LRU list if needed */
	__attribute__((malloc));

/**************************************************************************
Deallocate a block. */

void
buf_buddy_free_low(
/*===============*/
	void*	buf,	/* in: block to free */
	ulint	i)	/* in: index of buf_pool->zip_free[] */
	__attribute__((nonnull));

/**************************************************************************
Get the offset of the buddy of a compressed page frame. */
UNIV_INLINE
lint
buf_buddy_get_offset(
/*=================*/
				/* out: offset of the buddy relative to page */
	const void*	page,	/* in: compressed page */
	ulint		size)	/* in: page size in bytes */
{
	ut_ad(ut_is_2pow(size));
	ut_ad(size >= BUF_BUDDY_LOW);
	ut_ad(size < BUF_BUDDY_HIGH);

	if (((ulint) page) & size) {
		return(-(lint) size);
	} else {
		return((lint) size);
	}
}

/**************************************************************************
Get the index of buf_pool->zip_free[] for a given block size. */
UNIV_INLINE
ulint
buf_buddy_get_slot(
/*===============*/
			/* out: index of buf_pool->zip_free[] */
	ulint	size)	/* in: block size */
{
	ulint	i;
	ulint	s;

	for (i = 0, s = BUF_BUDDY_LOW; s < size; i++, s <<= 1);

	ut_ad(i < BUF_BUDDY_SIZES);
	return(i);
}

/**************************************************************************
Allocate a block. */
UNIV_INLINE
void*
buf_buddy_alloc(
/*============*/
			/* out: pointer to the start of the block */
	ulint	size,	/* in: block size, up to UNIV_PAGE_SIZE / 2 */
	ibool	lru)	/* in: TRUE=allocate from the LRU list if needed */
{
#ifdef UNIV_SYNC_DEBUG
	ut_a(mutex_own(&buf_pool->mutex));
#endif /* UNIV_SYNC_DEBUG */

	return(buf_buddy_alloc_low(buf_buddy_get_slot(size), lru));
}

/**************************************************************************
Deallocate a block. */
UNIV_INLINE
void
buf_buddy_free(
/*===========*/
	void*	buf,	/* in: block to free */
	ulint	size)	/* in: block size, up to UNIV_PAGE_SIZE / 2 */
{
#ifdef UNIV_SYNC_DEBUG
	ut_a(mutex_own(&buf_pool->mutex));
#endif /* UNIV_SYNC_DEBUG */

	buf_buddy_free_low(buf, buf_buddy_get_slot(size));
}

#ifdef UNIV_MATERIALIZE
# undef UNIV_INLINE
# define UNIV_INLINE	UNIV_INLINE_ORIGINAL
#endif