/usr/share/psychtoolbox-3/PsychBasic/RestrictKeysForKbCheck.m is in psychtoolbox-3-common 3.0.11.20140816.dfsg1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 52 53 54 55 56 57 58 59 | function ret = RestrictKeysForKbCheck(enablekeys)
% Restrict operation of KbCheck et al. to a subset of keys on the keyboard.
%
% oldenablekeys = RestrictKeysForKbCheck([enablekeys])
%
% Specify a vector of keycodes for keys which should be
% checked/used by KbCheck and KbWait. This is useful to
% only enable specific keys, e.g., to save time. The function
% returns the old set of enabled keys.
%
% Example: To enable the keys with keycodes 4, 6 and 7, do
% RestrictKeysForKbCheck([4, 6, 7]);
%
% Calling RestrictKeysForKbCheck([]); ie., with an empty vector, will
% reenable all keys.
%
% Caution: This setting is reset to "empty" during a "clear all" command,
% ie., all keys will be enabled again after a "clear all"!
%
% Background info:
%
% Some users of Laptops experienced the problem of "stuck keys": Some keys
% are always reported as "down", so KbWait returns immediately and KbCheck
% always reports keyIsDown == 1. This is often due to special function keys.
% These keys or system functionality are assigned vendor specific
% key codes, e.g., the status of the Laptop lid (opened/closed) could be
% reported by some special keycode. Whenever the Laptop lid is open, this key
% will be reported as pressed. You can work around this problem by passing
% a subset of keycodes to be used by KbCheck and KbWait, whereas all other
% unwanted keys are ignored.
%
% Another advantage is a significant speed gain for KbCheck et al. on
% MacOS/X systems, where the execution time of KbChecks is proportional to
% the number of keys to check.
% _________________________________________________________________________
%
% See also: FlushEvents, KbName, KbDemo, KbWait, KbCheck, GetChar, CharAvail.
% History:
% 11/16/08 Written (MK).
% This global variable is used to pass the vector of enabled keys
% to the KbCheck command:
global ptb_kbcheck_enabledKeys;
% Return old vector:
ret = find(ptb_kbcheck_enabledKeys > 0);
if nargin>0
% Set new vector:
if isempty(enablekeys)
ptb_kbcheck_enabledKeys = [];
else
ptb_kbcheck_enabledKeys = zeros(1,256);
ptb_kbcheck_enabledKeys(enablekeys) = 1;
end
end
return;
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