Matlab code to parse an OSC message into a vector of floats

 function [message args] = parse_message(bytes)
 % Parse a single OSC message whose arguments are all floats,
 % returning a matlab string for the address and a vector of floats
 % for the arguments
 
 message = ''; args = [];
 
 firstnull = find(bytes==0,1);
 
 if isempty(firstnull) 
 disp(['Invalid OSC message (no null character = no string = no address)']);
 return
 end
 
 % zero vs one origin indicing meets OSC's possible extra null characters
 % to bring all strings up to a multiple of 4-byte length
 lastnullafteraddress = firstnull + 3 - mod(firstnull-1, 4);
 
 for i=firstnull:lastnullafteraddress
 if bytes(i) ~= 0
 disp(['Invalid OSC message (improper string termination)'])
 return
 end
 end
 
 message = char(bytes(1:firstnull-1)');
 
 % Got the message, now throw away those bytes
 bytes = bytes(lastnullafteraddress+1:end);
 
 
 firstnull = find(bytes==0,1);
 
 if isempty(firstnull)
 disp(['Invalid OSC message (missing type tag string?)']);
 return
 end
 % zero vs one origin indicing meets OSC's possible extra null characters
 % to bring all strings up to a multiple of 4-byte length
 
 lastnullaftertypetags = firstnull + 3 - mod(firstnull-1, 4);
 
 for i=firstnull:lastnullaftertypetags
 if bytes(i) ~= 0
 disp(['Invalid OSC message (typetag has improper string termination)'])
 return
 end
 end
 
 
 
 typetags = char(bytes(1:firstnull-1));
 argbytes = bytes(lastnullaftertypetags+1:end);
 
 
 if typetags(1) ~= ','
 disp(['Invalid OSC message (type tag string needs leading comma)']);
 return
 end
 
 if ~all(typetags(2:end) == 'f')
 disp(['Sorry; I only handle floating point arguments, not ' typetags]);
 return
 end 
 
 
 % Chop into groups of 4 bytes
 for i = 1:4:length(argbytes)
 % big->little endian and interpret bytes as 32-bit float
 f = typecast(uint8(argbytes(i+3:-1:i)),'single');
 args = [args f];
 end
 
 end

 function udp_listen(handler, port, timeout, address)
 % function udp_listen(handler, port, timeout, address)
 %
 % udp_listen accepts 4 arguments:
 %
 % handler - a function that accepts a column vector of bytes and returns nothing
 % port - the port on which to listen
 % timeout - the number of seconds to wait before giving up on a single read
 % address - the ipv4 address on which to listen
 %
 % try these examples:
 %
 % udp_listen(@(bytes) disp(bytes'), 12345, 0.01, '127.0.0.1')
 % udp_listen(@(bytes) disp(char(bytes')), 12345, 0.01, '127.0.0.1')
 %
 
 % open a udp socket and listen
 %
 udp_object = udp(address, ...
 'LocalPort', port, ...
 'Timeout', timeout, ...
 'Terminator', '', ...
 'InputBufferSize', 65536);
 fopen(udp_object);
 
 % ensure that the udp socket gets destroyed when this function is done
 %
 localObject = onCleanup(@() delete(udp_object));
 
 % loop forever (until ctrl-c, matlab shutdown, crash, or earthquake)
 %
 while true
 try
 [data, count, error_message, from_address, from_port] = fread(udp_object);
 
 % uncomment for debugging
 disp(['got ', int2str(count), ' bytes from ', from_address, ':', int2str(from_port)])
 
 if isempty(data)
 disp(['still listening...']);
 else
 handler(data);
 end
 
 catch me
 % hide errors/exceptions when we break this infinite loop with ctrl-c
 % we should actually check if this is exception is ctrl-c related (TBD)
 %
 disp(['Exception caught ', me])
 return
 end
 end
 end