[boost] date_time using CPU performance counter

Subject: [boost] date_time using CPU performance counter
From: Kenneth Porter (shiva.blacklist_at_[hidden])
Date: 2011-11-17 14:28:23

I need high precision under Windows XP but don't need long-term date 
accuracy. To that end, I think it would be useful to have a microsec_clock 
implemented in terms of the Windows QueryPerformanceCounter API (which 
wraps a CPU register query) instead of the GetSystemTimeAsFileTime API 
(which is only good to 15 msecs and almost guarantees a context switch).

Has anyone attempted this? How hard is it to code up a new clock source to 
fit into the Boost date_time design?