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88 lines
2.5 KiB
C++
88 lines
2.5 KiB
C++
/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
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// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
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#ident "$Id$"
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#ident "Copyright (c) 2007 Tokutek Inc. All rights reserved."
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/* Purpose of this file is to provide definitions of
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* Host to Disk byte transposition functions, an abstraction of
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* htod32()/dtoh32() and htod16()/dtoh16() functions.
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*
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* These htod/dtoh functions will only perform the transposition
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* if the disk and host are defined to be in opposite endian-ness.
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* If we define the disk to be in host order, then no byte
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* transposition is performed. (We might do this to save the
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* the time used for byte transposition.)
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*
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* This abstraction layer allows us to define the disk to be in
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* any byte order with a single compile-time switch (in htod.c).
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*
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* NOTE: THIS FILE DOES NOT CURRENTLY SUPPORT A BIG-ENDIAN
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* HOST AND A LITTLE-ENDIAN DISK.
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*/
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#ifndef _TOKU_HTOD_H
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#define _TOKU_HTOD_H
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#include <config.h>
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#if defined(HAVE_ENDIAN_H)
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# include <endian.h>
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#elif defined(HAVE_MACHINE_ENDIAN_H)
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# include <machine/endian.h>
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# define __BYTE_ORDER __DARWIN_BYTE_ORDER
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# define __LITTLE_ENDIAN __DARWIN_LITTLE_ENDIAN
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# define __BIG_ENDIAN __DARWIN_BIG_ENDIAN
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#endif
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#if !defined(__BYTE_ORDER) || \
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!defined(__LITTLE_ENDIAN) || \
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!defined(__BIG_ENDIAN)
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#error Standard endianness things not all defined
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#endif
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static const int64_t toku_byte_order_host = 0x0102030405060708LL;
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#define NETWORK_BYTE_ORDER (__BIG_ENDIAN)
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#define INTEL_BYTE_ORDER (__LITTLE_ENDIAN)
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#define HOST_BYTE_ORDER (__BYTE_ORDER)
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//DISK_BYTE_ORDER is the byte ordering for integers written to disk.
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//If DISK_BYTE_ORDER is the same as HOST_BYTE_ORDER no conversions are necessary.
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//Otherwise some structures require conversion to HOST_BYTE_ORDER on loading from disk (HOST_BYTE_ORDER in memory), and
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//others require conversion to HOST_BYTE_ORDER on every access/mutate (DISK_BYTE_ORDER in memory).
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#define DISK_BYTE_ORDER (INTEL_BYTE_ORDER)
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#if HOST_BYTE_ORDER!=INTEL_BYTE_ORDER
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//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.
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#error Only intel byte order supported so far.
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#endif
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#if DISK_BYTE_ORDER == HOST_BYTE_ORDER
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static inline uint64_t
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toku_dtoh64(uint64_t i) {
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return i;
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}
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static inline uint64_t
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toku_htod64(uint64_t i) {
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return i;
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}
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static inline uint32_t
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toku_dtoh32(uint32_t i) {
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return i;
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}
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static inline uint32_t
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toku_htod32(uint32_t i) {
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return i;
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}
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#else
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#error Not supported
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#endif
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#endif
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