CoreAudio/PublicUtility/CATink.h
/* |
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// as the APIs that made tinks useful have been replaced by APIs that do away |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 |
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