[boost] Re: xtime_get unsafe on Windows for IA64

From: Michael Glassford (glassfordm_at_[hidden])
Date: 2004-09-16 14:03:06

Michael Glassford wrote:
> Ben Hutchings wrote:
> 
>> Michael Glassford <glassfordm_at_[hidden]> wrote:
>>
>>> Ben Hutchings wrote:
>>>
>>>> The implementation of the boost::xtime_get() function in
>>>> libs/thread/src/xtime.cpp includes the following code for Windows:
>>
>>
>> <snip>
>>
>>>> The pointer casts are not safe because although the representations
>>>> of FILETIME and __int64 are compatible, FILETIME is only 32-bit-
>>>> aligned whereas __int64 must be 64-bit-aligned on IA64 (in some
>>>> processor modes).
>>>>
>>>> One can instead use union { FILETIME ft; __int64 i64; } and read out
>>>> i64, though I'm not sure this code should be unconditionally using
>>>> __int64 anyway.  There is a longer explanation at
>>>> <http://weblogs.asp.net/oldnewthing/archive/2004/08/25/220195.aspx>.
>>>
>>>
>>> How about this instead:
>>>
>>>     const boost::uint64_t TIMESPEC_TO_FILETIME_OFFSET =
>>>         (static_cast<boost::uint64_t>(27111902UL) << 32)
>>>         + 3577643008UL;
>>
>>
>>
>> I think this should use the UINT64_C macro instead of messing about
>> with casts.
> 
> 
> OK.
> 
> I see this is defined in boost/cstdint.hpp, but only if 
> __STDC_CONSTANT_MACROS is #defined. How does this happen? Do I #define 
> it myself, or does it get #defined some other way?
> 

Any help on how to use the Boost UINT64_C macro?

Mike