page.h

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// ============================================================================
// Project:     Deductive Database
// Filename:    page.h
// Purpose:     A memory page
// Last Change: 03.08.2017
// Language:    C++
// EMail:       brass@informatik.uni-halle.de
// WWW:         http://www.informatik.uni-halle.de/~brass/
// Address:     Feldschloesschen 15, D-06120 Halle (Saale), GERMANY
// Copyright:   (c) 2015-2017 by Stefan Brass
// License:     See file "LICENSE" for copying conditions.
// Note:        There is no warranty at all - this code may contain bugs.
// ============================================================================


//=============================================================================
// Include File Frame:
//=============================================================================

#ifndef PAGE_INCLUDED
#define PAGE_INCLUDED


//=============================================================================
// Used Types and Macros:
//=============================================================================

#ifndef VER_INCLUDED
#include "../base/ver.h"
#endif

#ifndef CHECK_INCLUDED
#include "../base/check.h"
#endif


//=============================================================================
// Basic Types and Macros for Memory Pages:
//=============================================================================

//-----------------------------------------------------------------------------
// Type of memory pages (pointer to start of VER_PAGESIZE bytes):
//-----------------------------------------------------------------------------

typedef void *page_t;

//-----------------------------------------------------------------------------
// Define null pointer:
//-----------------------------------------------------------------------------

#define PAGE_NULL (static_cast<page_t>(0))

//=============================================================================
// For Pages Used for Storing Objects of Only One Type:
//=============================================================================

//-----------------------------------------------------------------------------
// Size of a page in variables of a given type T:
//-----------------------------------------------------------------------------

#define PAGE_SIZE(TYPE)  \
        (VER_PAGESIZE/static_cast<int>(sizeof(TYPE)))

//=============================================================================
// For Pages Used for Storing Objects of Different Types:
//=============================================================================

//-----------------------------------------------------------------------------
// Union with maximal alignment requirements (unit for memory allocation):
//-----------------------------------------------------------------------------

union page_u {
        int i;
        long l;
        double d;
        str_t s;
        void *p;
        VER_INT64 i64;
};

//-----------------------------------------------------------------------------
// Define pointer type:
//-----------------------------------------------------------------------------

typedef union page_u *page_u_t;

//-----------------------------------------------------------------------------
// Define null pointer:
//-----------------------------------------------------------------------------

#define PAGE_U_NULL (static_cast<page_u_t>(0))

//-----------------------------------------------------------------------------
// Size of page units:
//-----------------------------------------------------------------------------

#define PAGE_UNIT_BYTES \
        (static_cast<int>(sizeof(union page_u)))

//-----------------------------------------------------------------------------
// Size of a type in page units:
//-----------------------------------------------------------------------------

#define PAGE_UNITS(TYPE) \
        ((static_cast<int>(sizeof(TYPE))+PAGE_UNIT_BYTES-1) / PAGE_UNIT_BYTES)

//-----------------------------------------------------------------------------
// Size of memory page in units:
//-----------------------------------------------------------------------------

#define PAGE_SIZE_UNITS \
        (VER_PAGESIZE / PAGE_UNIT_BYTES)


//=============================================================================
// Other macros:
//=============================================================================

//-----------------------------------------------------------------------------
// Translate number of pages to number of kilobytes:
//-----------------------------------------------------------------------------

#define PAGE_KB(NUM_PAGES) \
        (static_cast<int>( \
                (static_cast<long>(NUM_PAGES) * VER_PAGESIZE) / 1024))

//=============================================================================
// End of Include File:
//=============================================================================

#endif