I was just following up on my previous reply and was puzzled by the implementation of
this fn.
XMLPlatformUtils::compareAndSwap( void** toFill
, const void* const newValue
, const void* const toCompare)
{
#if defined WIN64
return ::InterlockedCompareExchangePointer(toFill, (void*)newValue,
(void*)toCompare);
#else
//
// InterlockedCompareExchange is only supported on Windows 98,
// Windows NT 4.0, and newer -- not on Windows 95...
// If you are willing to give up Win95 support change this to #if 0
// otherwise we are back to using assembler.
// (But only if building with compilers that support inline assembler.)
//
#if defined(_MSC_VER) || defined(__BCPLUSPLUS__)
void* result;
__asm
{
mov eax, toCompare;
mov ebx, newValue;
mov ecx, toFill
lock cmpxchg [ecx], ebx;
mov result, eax;
}
return result;
#else
//
// Note we have to cast off the constness of some of these because
// the system APIs are not C++ aware in all cases.
//
return (void*) ::InterlockedCompareExchange((LPLONG)toFill, (LONG)newValue,
(LONG)toCompare);
#endif
#endif
}
here, the developer has used #if defined(_MSC_VER) to branch to his inline assembly
code. But _MSC_VER is ALWAYS defined on Most windows versions. So, I guess we would
always be hitting the assembly code (unless you are using win64). Does someone think
this if define condition needs modifying ? we may probably want to use _WIN32_WINNT or
atleast check if _MSC_VER > 1000 or something like that.
-Vinayak
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