readmsg.m

一个MATLAB的应用程序

function data = readmsg(varargin)
%READMSG Read data messages from specified RDTX(tm) channel.
%   DATA = READMSG(R, CHANNELNAME, DATATYPE, SIZ, NUMMSGS, TIMEOUT) reads 
%   NUMMSGS number of data messages of type DATATYPE from a 'read' configured 
%   RTDX channel queue specified by the string CHANNEL, and as defined in the 
%   RTDX object R.  The output data is formatted as a single-row cell-array of
%   NUMMSGS number of matrices whose dimensions are specified by the dimension 
%   vector SIZ.  If NUMMSGS is set to 'all' or 'ALL', all messages in the 
%   channel queue at the time of the method call will be read.  The number of 
%   elements of the output matrix must correspond exactly to the number of 
%   elements in the corresponding message.  TIMEOUT in units of seconds is used
%   instead of the global timeout stored in the object R.  If the specified 
%   number of messages, NUMMSGS, is not available in the channel queue when 
%   this method is called, the routine will enter a 'wait' loop until either 
%   the full complement of data is made available, or the timeout period 
%   expires.
%       DATATYPE:    'uint8'
%                    'int16'
%                    'int32'
%                    'single'
%                    'double'
%
%   DATA = READMSG(R, CHANNELNAME, DATATYPE, SIZ, NUMMSGS) reads NUMMSGS number
%   of messages as described above, using the global time value stored in the
%   object R.
%
%   DATA = READMSG(R, CHANNELNAME, DATATYPE, SIZ) reads a single data message
%   as NUMMSGS defaults to 1.
%
%   DATA = READMSG(R, CHANNELNAME, DATATYPE, NUMMSGS) reads NUMMSGS messages, 
%   and returns the messages as a single-row cell array of row matrices of the
%   form [data(1) data(N)], where N is equal to the number of data values in 
%   the current message, i.e., SIZ defaults to [1 N].  Unlike the above calling
%   sequences, the length of each message can be of variable length.
%
%   DATA = READMSG(R, CHANNELNAME, DATATYPE) reads one message and returns a 
%   single row vector.  Defaults apply for all unspecified input arguments.
%
%   In all of the above cases, SIZ and NUMMSGS may be set to an empty matrix, 
%   in which case the defaults discussed above are substituted.
%
%   WARNING: If the timeout expires before the requested number of messages
%            have been read from the channel, all messages read to that point 
%            will be lost.
%
%   Example:
%
%       outData = readmsg(cc.rtdx, 'ochan', 'int32', [3 5], 2);
%
%       Two messages of data type 'int32' are read from the read-configured
%       channel named 'ochan'.  Both messages are formatted as 3x5 matrices and
%       returned in a 1x2 cell array, outData, of matrices.
%   See also READMAT, WRITEMSG
%

% Copyright 2002 The MathWorks, Inc.