/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
#ident "$Id$"
/*======
This file is part of PerconaFT.


Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.

    PerconaFT is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License, version 2,
    as published by the Free Software Foundation.

    PerconaFT 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 for more details.

    You should have received a copy of the GNU General Public License
    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.

----------------------------------------

    PerconaFT is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License, version 3,
    as published by the Free Software Foundation.

    PerconaFT 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 Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
======= */

#ident "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."

#pragma once

/* Purpose of this file is to provide definitions of 
 * Host to Disk byte transposition functions, an abstraction of
 * htod32()/dtoh32() and htod16()/dtoh16() functions.
 *
 * These htod/dtoh functions will only perform the transposition
 * if the disk and host are defined to be in opposite endian-ness.
 * If we define the disk to be in host order, then no byte 
 * transposition is performed.  (We might do this to save the 
 * the time used for byte transposition.) 
 * 
 * This abstraction layer allows us to define the disk to be in
 * any byte order with a single compile-time switch (in htod.c).
 *
 * NOTE: THIS FILE DOES NOT CURRENTLY SUPPORT A BIG-ENDIAN
 *       HOST AND A LITTLE-ENDIAN DISK.
 */

#include <portability/toku_config.h>

#if defined(HAVE_ENDIAN_H)
# include <endian.h>
#elif defined(HAVE_MACHINE_ENDIAN_H)
# include <machine/endian.h>
# define __BYTE_ORDER __DARWIN_BYTE_ORDER
# define __LITTLE_ENDIAN __DARWIN_LITTLE_ENDIAN
# define __BIG_ENDIAN __DARWIN_BIG_ENDIAN
#endif
#if !defined(__BYTE_ORDER) || \
    !defined(__LITTLE_ENDIAN) || \
    !defined(__BIG_ENDIAN)
#error Standard endianness things not all defined
#endif


static const int64_t toku_byte_order_host = 0x0102030405060708LL;

#define NETWORK_BYTE_ORDER  (__BIG_ENDIAN)
#define INTEL_BYTE_ORDER    (__LITTLE_ENDIAN)
#define HOST_BYTE_ORDER     (__BYTE_ORDER)

//DISK_BYTE_ORDER is the byte ordering for integers written to disk.
//If DISK_BYTE_ORDER is the same as HOST_BYTE_ORDER no conversions are necessary.
//Otherwise some structures require conversion to HOST_BYTE_ORDER on loading from disk (HOST_BYTE_ORDER in memory), and
//others require conversion to HOST_BYTE_ORDER on every access/mutate (DISK_BYTE_ORDER in memory).
#define DISK_BYTE_ORDER     (INTEL_BYTE_ORDER)

#if HOST_BYTE_ORDER!=INTEL_BYTE_ORDER
//Even though the functions are noops if DISK==HOST, we do not have the logic to test whether the file was moved from another BYTE_ORDER machine.
#error Only intel byte order supported so far.
#endif

#if DISK_BYTE_ORDER == HOST_BYTE_ORDER
static inline uint64_t
toku_dtoh64(uint64_t i) {
    return i;
}

static inline uint64_t
toku_htod64(uint64_t i) {
    return i;
}

static inline uint32_t
toku_dtoh32(uint32_t i) {
    return i;
}

static inline uint32_t
toku_htod32(uint32_t i) {
    return i;
}
#else
#error Not supported
#endif