/usr/share/psychtoolbox-3/PsychBasic/MachAbsoluteTimeClockFrequency.m is in psychtoolbox-3-common 3.0.11.20131230.dfsg1-1build1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 | function timebaseFrequencyHz = MachAbsoluteTimeClockFrequency
% timebaseFrequencyHz = MachAbsoluteTimeClockFrequency
%
% OS X: ___________________________________________________________________
%
% Return the frequency of the Mach Kernel "absolute timebase clock". The
% frequency depends your hardware, both the model of CPU and a system
% hardware clock.
%
% Mach Kernel functions which assign real-time "Time constraint priority"
% status to threads give parameters in Mach time base units. The counter which
% clocks time allocated to your thread counts time in these units. Use the
% absolute timebase clock frequency returned by MachAbsoluteTimeClockFrequency to convert
% seconds into absolute timebase units which you pass to functions which
% set which set priority:
%
% time_interval_in_mach_units=
% time_interval_in_seconds * timebaseFrequencyHz;
%
% For more information on the Mach absolute time clock see Apple Technical
% Q&A 1398:
%
% http://developer.apple.com/qa/qa2004/qa1398.html
%
% OS 9: ___________________________________________________________________
%
% MachAbsoluteTimeClockFrequency is not provided on OS 9 because the Mach
% time base is a feature of only the OS X Mach Kernel.
%
%
% WINDOWS: ________________________________________________________________
%
% MachAbsoluteTimeClockFrequency is not provided on Windows because the
% Mach time base is a feature of only the OS X Mach Kernel.
% _________________________________________________________________________
%
% see also: Priority
% HISTORY
% 4/6/05 awi Wrote it. Based on Mario's changes to GetBusFrequencyMex
% 4/8/05 awi Added link to Q&A 1398
% 4/8/05 awi Updated "MachTimebase" to new name "MachAbsoluteTimeClockFrequency"
% On OS X MATLAb should find and execute a mex file of the same name,
% not this help file. So issue and error about a missing mex file if this
% help file executes on OSX.
AssertMex('OSX');
% On every platform except OS X we arrive here.
error('The Mach absolute time clock is a feature of only the Mac OS X Mach Kernel.');
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