ImfVersion.h

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//
// SPDX-License-Identifier: BSD-3-Clause
// Copyright (c) Contributors to the OpenEXR Project.
//

#ifndef INCLUDED_IMF_VERSION_H
#define INCLUDED_IMF_VERSION_H

//-----------------------------------------------------------------------------
//
//      Magic and version number.
//
//-----------------------------------------------------------------------------

#include "ImfExport.h"
#include "ImfNamespace.h"

OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_ENTER

//
// The MAGIC number is stored in the first four bytes of every
// OpenEXR image file.  This can be used to quickly test whether
// a given file is an OpenEXR image file (see isImfMagic(), below).
//

static const int MAGIC = 20000630;

//
// The second item in each OpenEXR image file, right after the
// magic number, is a four-byte file version identifier.  Depending
// on a file's version identifier, a file reader can enable various
// backwards-compatibility switches, or it can quickly reject files
// that it cannot read.
//
// The version identifier is split into an 8-bit version number,
// and a 24-bit flags field.
//

static const int VERSION_NUMBER_FIELD = 0x000000ff;
static const int VERSION_FLAGS_FIELD  = 0xffffff00;

//
// Value that goes into VERSION_NUMBER_FIELD.
//

static const int EXR_VERSION = 2;

//
// Flags that can go into VERSION_FLAGS_FIELD.
// Flags can only occupy the 1 bits in VERSION_FLAGS_FIELD.
//

static const int TILED_FLAG      = 0x00000200; // File is tiled
static const int LONG_NAMES_FLAG = 0x00000400; // File contains long
                                               // attribute or channel
                                               // names
static const int NON_IMAGE_FLAG = 0x00000800;  // File has at least one part
                                               // which is not a regular
// scanline image or regular tiled image
// (that is, it is a deep format)
static const int MULTI_PART_FILE_FLAG = 0x00001000; // File has multiple parts

//
// Bitwise OR of all known flags.
//
static const int ALL_FLAGS =
    TILED_FLAG | LONG_NAMES_FLAG | NON_IMAGE_FLAG | MULTI_PART_FILE_FLAG;

//
// Utility functions
//

inline bool
isTiled (int version)
{
    return !!(version & TILED_FLAG);
}
inline bool
isMultiPart (int version)
{
    return !!(version & MULTI_PART_FILE_FLAG);
}
inline bool
isNonImage (int version)
{
    return !!(version & NON_IMAGE_FLAG);
}
inline int
makeTiled (int version)
{
    return version | TILED_FLAG;
}
inline int
makeNotTiled (int version)
{
    return version & ~TILED_FLAG;
}
inline int
getVersion (int version)
{
    return version & VERSION_NUMBER_FIELD;
}
inline int
getFlags (int version)
{
    return version & VERSION_FLAGS_FIELD;
}
inline bool
supportsFlags (int flags)
{
    return !(flags & ~ALL_FLAGS);
}

//
// Given the first four bytes of a file, returns true if the
// file is probably an OpenEXR image file, false if not.
//

IMF_EXPORT
bool isImfMagic (const char bytes[4]);

OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_EXIT

#endif