OSCrossEndian.h   [plain text]

/*
 * Copyright (c) 2000-2006 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */

/*
 * This private header exports 3 APIs.
 *	_OSRosettaCheck() - 	An inline function that returns true if we are
 *				currently running under Rosetta.
 *	IF_ROSETTA() -		Which is used to as a regular conditional
 *				expression that is true only if the current
 *				code is executing in the Rosetta
 *				translation space.
 *	ROSETTA_ONLY(exprs) - 	Which is used to create a block code that only
 *				executes if we are running in Rosetta.
 *
 * for example
 *
 * IF_ROSETTA() {
 *	// Do Cross endian swapping of input data
 *	outdata = OSSwap??(indata);
 * }
 * else {
 * 	// Do straight through 
 *	outdata = indata;
 * }
 *
 * outdata = indata;
 * ROSETTA_ONLY(
 *	// Do Cross endian swapping of input data
 *	outdata = OSSwap??(outdata);
 * );
 */

#ifndef _LIBKERN_OSCROSSENDIAN_H
#define _LIBKERN_OSCROSSENDIAN_H

#include <sys/sysctl.h>

#if __ppc__

static __inline__ int
_OSRosettaCheck(void)
{
	int isCrossEndian = 0;
	int val = 0;
	size_t size = sizeof val;

	if (sysctlbyname("sysctl.proc_native", &val, &size, NULL, 0) == -1)
		isCrossEndian = 0;
	else
		isCrossEndian = val ? 0 : 1;

	return isCrossEndian;
}

#else /* __ppc__ */

static __inline__ int _OSRosettaCheck(void) { return 0; }

#endif /* __ppc__ */

#define IF_ROSETTA() if (__builtin_expect(_OSRosettaCheck(), 0) )

#define ROSETTA_ONLY(exprs)	\
do {				\
    IF_ROSETTA() {		\
	exprs			\
    }				\
} while(0)

#endif /*  _LIBKERN_OSCROSSENDIAN_H */