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/** @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 */
#define 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 */
UNIV_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 */
UNIV_INLINE
ibool 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 */
UNIV_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 */
UNIV_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 */
UNIV_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