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livetrax/libs/appleutility/CoreAudio/PublicUtility/CATink.h

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/*
File: CATink.h
Abstract: Part of CoreAudio Utility Classes
Version: 1.1
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*/
#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// as the APIs that made tinks useful have been replaced by APIs that do away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