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/*
File: CATink.h
Abstract: Part of CoreAudio Utility Classes
Version: 1.1
Disclaimer: IMPORTANT: This Apple software is supplied to you by Apple
Inc. ("Apple") in consideration of your agreement to the following
terms, and your use, installation, modification or redistribution of
this Apple software constitutes acceptance of these terms. If you do
not agree with these terms, please do not use, install, modify or
redistribute this Apple software.
In consideration of your agreement to abide by the following terms, and
subject to these terms, Apple grants you a personal, non-exclusive
license, under Apple's copyrights in this original Apple software (the
"Apple Software"), to use, reproduce, modify and redistribute the Apple
Software, with or without modifications, in source and/or binary forms;
provided that if you redistribute the Apple Software in its entirety and
without modifications, you must retain this notice and the following
text and disclaimers in all such redistributions of the Apple Software.
Neither the name, trademarks, service marks or logos of Apple Inc. may
be used to endorse or promote products derived from the Apple Software
without specific prior written permission from Apple. Except as
expressly stated in this notice, no other rights or licenses, express or
implied, are granted by Apple herein, including but not limited to any
patent rights that may be infringed by your derivative works or by other
works in which the Apple Software may be incorporated.
The Apple Software is provided by Apple on an "AS IS" basis. APPLE
MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION
THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND
OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.
IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL
OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION,
MODIFICATION AND/OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED
AND WHETHER UNDER THEORY OF CONTRACT, TORT (INCLUDING NEGLIGENCE),
STRICT LIABILITY OR OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
Copyright (C) 2014 Apple Inc. All Rights Reserved.
*/
#if !defined(__CATink_h__)
#define __CATink_h__
//=============================================================================
// Includes
//=============================================================================
// System Includes
#if !defined(__COREAUDIO_USE_FLAT_INCLUDES__)
#include <CoreServices/CoreServices.h>
#else
#include <CoreServices.h>
#endif
//=============================================================================
// CATink
//
// A Tink is a small jump island that can make one function appear as if it
// has many addresses. Note that Tinks are not supported for 64 bit environments
// as the APIs that made tinks useful have been replaced by APIs that do away
// with all the reasons for using a tink.
//=============================================================================
template <class F>
class CATink
{
public:
CATink(F proc) { Set(proc); }
~CATink() { Set((F)0xDEADDEAD); } // jump to an obviously bad (odd) address if accessed after destruction
#if TARGET_CPU_PPC
void Set(F proc)
{
/*
lis r11,0x1234
00000000: 3D601234 lis r11,4660
ori r11,r11,0x5678
00000004: 616B5678 ori r11,r11,$5678
mtctr r11
00000008: 7D6903A6 mtctr r11
bctr
0000000C: 4E800420 bctr
*/
UInt32 p = UInt32(proc);
mCode[0] = 0x3D600000 | (p >> 16);
mCode[1] = 0x616B0000 | (p & 0xFFFF);
mCode[2] = 0x7D6903A6;
mCode[3] = 0x4E800420;
MakeDataExecutable(mCode, sizeof(mCode));
}
operator F () { return F(mCode); }
private:
UInt32 mCode[4];
#elif TARGET_CPU_X86
void Set(F proc)
{
/*
<tink>: push $0x12345678
<tink+5>: ret
<tink>: 0x34567868
<tink+4>: 0x00e8c312
*/
UInt32 p = UInt32(proc);
mCode[0] = ((p & 0xFFFFFF) << 8) | 0x00000068;
mCode[1] = 0xCCCCC300 | (p >> 24);
MakeDataExecutable(mCode, sizeof(mCode));
}
operator F () { return F(&mCode[0]); }
private:
UInt32 mCode[2];
#else
#warning: CPU not directly supported by CATink
// For other CPU's, just wrap the function pointer for now.
// this bypasses what we're trying to accomplish with the Tink
// (multiple unique "instances" of a function), but it will at
// least compile and run.
void Set(F proc) { mProcPtr = proc; }
operator F () { return mProcPtr; }
private:
F mProcPtr;
#endif
// Tinks cannot be allocated in STL Containers, so we make a few key methods private
private:
CATink(){}
CATink(const CATink&){}
CATink& operator=(const CATink&){ return *this;}
};
#endif
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