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/*****************************************************************************
Copyright (c) 2005, 2025, Oracle and/or its affiliates.
Copyright (c) 2012, Facebook Inc.
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License, version 2.0, as published by the
Free Software Foundation.
This program is designed to work with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation. The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have either included with
the program or referenced in the documentation.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License, version 2.0,
for more details.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*****************************************************************************/
/** @file page/zipdecompress.ic
Compressed page interface
Created June 2005 by Marko Makela
*******************************************************/
/** NOTE: The functions in this file should only use functions from
other files in library. The code in this file is used to make a library for
external tools. */
#ifndef zip_decompress_ic
#define zip_decompress_ic
#include "btr0types.h"
#include "fil0types.h"
#include "page0types.h"
#include "page/page.ic"
/** Size of an compressed page directory entry */
constexpr uint32_t PAGE_ZIP_DIR_SLOT_SIZE = 2;
/** Gets a pointer to the compressed page trailer (the dense page directory),
including deleted records (the free list).
@param[in] page_zip compressed page
@param[in] n_dense number of entries in the directory
@return pointer to the dense page directory */
#define page_zip_dir_start_low(page_zip, n_dense) \
((page_zip)->data + page_zip_dir_start_offs(page_zip, n_dense))
/** Gets a pointer to the compressed page trailer (the dense page directory),
including deleted records (the free list).
@param[in] page_zip compressed page
@return pointer to the dense page directory */
#define page_zip_dir_start(page_zip) \
page_zip_dir_start_low(page_zip, page_zip_dir_elems(page_zip))
/** Determine the size of a compressed page in bytes.
@return size in bytes */
static inline ulint page_zip_get_size(
const page_zip_des_t *page_zip) /*!< in: compressed page */
{
ulint size;
if (!page_zip->ssize) {
return (0);
}
size = (UNIV_ZIP_SIZE_MIN >> 1) << page_zip->ssize;
ut_ad(size >= UNIV_ZIP_SIZE_MIN);
ut_ad(size <= UNIV_PAGE_SIZE);
return (size);
}
#ifdef UNIV_DEBUG
/** Validate a compressed page descriptor.
@return true if ok */
static inline bool page_zip_simple_validate(
const page_zip_des_t *page_zip) /*!< in: compressed page descriptor */
{
ut_ad(page_zip);
ut_ad(page_zip->data);
ut_ad(page_zip->ssize <= PAGE_ZIP_SSIZE_MAX);
ut_ad(page_zip_get_size(page_zip) > PAGE_DATA + PAGE_ZIP_DIR_SLOT_SIZE);
ut_ad(page_zip->m_start <= page_zip->m_end);
ut_ad(page_zip->m_end < page_zip_get_size(page_zip));
ut_ad(page_zip->n_blobs <
page_zip_get_size(page_zip) / BTR_EXTERN_FIELD_REF_SIZE);
return true;
}
#endif /* UNIV_DEBUG */
/** Gets the number of elements in the dense page directory,
including deleted records (the free list).
@return number of elements in the dense page directory */
static inline ulint page_zip_dir_elems(
const page_zip_des_t *page_zip) /*!< in: compressed page */
{
/* Exclude the page infimum and supremum from the record count. */
return (page_dir_get_n_heap(page_zip->data) - PAGE_HEAP_NO_USER_LOW);
}
/** Gets the size of the compressed page trailer (the dense page directory),
including deleted records (the free list).
@return length of dense page directory, in bytes */
static inline ulint page_zip_dir_size(
const page_zip_des_t *page_zip) /*!< in: compressed page */
{
return (PAGE_ZIP_DIR_SLOT_SIZE * page_zip_dir_elems(page_zip));
}
/** Read a given slot in the dense page directory.
@return record offset on the uncompressed page, possibly ORed with
PAGE_ZIP_DIR_SLOT_DEL or PAGE_ZIP_DIR_SLOT_OWNED */
static inline ulint page_zip_dir_get(
const page_zip_des_t *page_zip, /*!< in: compressed page */
ulint slot) /*!< in: slot
(0=first user record) */
{
ut_ad(page_zip_simple_validate(page_zip));
ut_ad(slot < page_zip_dir_size(page_zip) / PAGE_ZIP_DIR_SLOT_SIZE);
return (mach_read_from_2(page_zip->data + page_zip_get_size(page_zip) -
PAGE_ZIP_DIR_SLOT_SIZE * (slot + 1)));
}
#endif
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