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## Copyright (C) 2018 John Donoghue <john.donoghue@ieee.org>
##
## This program is free software: you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
## the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
##
## This program is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with this program. If not, see
## <https://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @deftypefn {} {@var{retval} =} read (@var{register})
## @deftypefnx {} {@var{retval} =} read (@var{register}, @var{precision})
## read a value from the shift register.
##
## @subsubheading Inputs
## @var{register} - shift register created from shiftRegister call.
##
## @var{precision} - optional precision of the data, where precision can be a
## number in a multiple of 8 (ie: 8,16,32) or can be a named integer type: 8
## of 'uint8', 'uint16', 'uint32'. The default precision is 8.
##
## @subsubheading Outputs
## @var{retval} - returned data read from the register.
##
## @seealso{shiftRegister, write}
## @end deftypefn
function out = read(register, precision)
persistent ARDUINO_SHIFTREG_READ = 3;
persistent endian;
if isempty(endian)
[~, ~, endian] = computer ();
endif
if nargin < 1 || nargin > 2
print_usage ();
endif
if nargin == 2
if ischar(precision)
precision = tolower(precision);
switch(precision)
case "uint8"
precision = 8;
case "uint16"
precision = 16;
case "uint32"
precision = 32;
otherwise
error ("unknown precsison value '%s'", precision)
endswitch
elseif isscalar(precision)
if precision <= 0 || mod(precision, 8) != 0
error ("precision should be positive number that is a muiltiple of 8");
endif
endif
else
precision = 8;
endif
# attempt to clock out precision bits
[tmp, sz] = sendCommand(register.parent, "shiftregister", ARDUINO_SHIFTREG_READ, [register.id precision]);
out = typecast(uint8(tmp(2:end)), ['uint' num2str(precision)]);
if (endian == 'L')
out = swapbytes (out);
endif
endfunction
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