readhex.m

这是一个关于MATLAB的函数

function resp = readhex(rn,index,timeout)
%READ2HEX Retrieves a block of DSP memory as hexadecimal strings.
%   DN = READ2HEX(NN)
%   DN = READ2HEX(NN,[],TIMEOUT)
%   DN = READ2HEX(NN,INDEX)
%   DN = READ2HEX(NN,INDEX,TIMEOUT)
%
%   HS = READ2HEX(NN) - returns a hex representation of the DSP's numeric 
%   values.  For arrays, the returned values will be a cell array
%   of hex strings.  Conversely, if NN.SIZE equals 1,
%   (indicating a scalar), the output is an array of hex characters. 
%
%   DN = READ2HEX(NN,TIMEOUT) - The time alloted to perform the read is 
%   limited  by the NN.TIMEOUT property of the NN object.  However, 
%   this method can be used to explicitly define a different timeout
%   for the read.  For example, this may be necessary for very large 
%   data transfers.
%  
%   See also WRITE, READ, CAST, NUMERICMEM.

%   Copyright 2002 The MathWorks, Inc.
%   $Revision: 1.3 $ $Date: 2002/03/23 02:46:27 $

error(nargchk(1,3,nargin));
if ~ishandle(rn),
    error('First Parameter must be a MEMORYOBJ Handle.');
end
% Call base class (memoryobj) to get unformatted data
if nargin == 1,
    uidata = read_registerobj(rn);
elseif nargin == 2, % index only (1 value)
    uidata = read_registerobj(rn,index);
elseif nargin == 3 & isempty(index),
    resp = read_registerobj(rn,1,timeout);
    % TBD
    % resp = read_memoryobj(rn,?,autype,1,timeout);
else
    resp = read_registerobj(rn,1,timeout);
end

% Re-arrange data as described by object
nvalues = prod(rn.size);
uidata = reshape(uidata,[rn.storageunitspervalue nvalues]);

% Endianness swap (if necessary)    
if ~strcmp( rn.endianness,'little') & (rn.storageunitspervalue > 1),
    uidata = flipud(uidata);
end

% Trim pre/post bytes (if necessary)
% For now, limited to increments of bitsperstorageunit
if rn.prepad > 0 |  rn.postpad > 0,
    if rn.prepad + rn.postpad > rn.storageunitspervalue * rn.bitsperstorageunit,
        error(' Pre/Post padding exceeds available memory area');
    end    
    % prepad
    uidata(1) = bitshift(uidata(1),-1 * rn.prepad,rn.bitsperstorageunit);
    % postpad
    uidata(end) = bitand( uidata(end),bitshift(2^rn.bitsperstorageunit-1,-rn.postpad,rn.bitsperstorageunit) );
end 

% convert adjusted array of 'valid' au into hex array
if nvalues == 1,
   resp{1} = reshape(fliplr(dec2hex(double(uidata),ceil(rn.bitsperstorageunit/4))'),1,[]);
else % create cell array TBD
   for iv=1:nvalues,
       resp{iv} = reshape(fliplr(dec2hex(double(uidata(:,iv)),ceil(rn.bitsperstorageunit/4))'),1,[]);
   end
   if length(rn.size) > 1,
        resp = reshape(resp,rn.size);
   end   
end

% [EOF] readhex.m