rtIOStreamBlockingSend and rtIOStreamBlockingRecv functions

Hi. I'm trying to implement Host/Target Communication using serial transfer. I used a guide from http://www.mathworks.de/de/help/rtw/ug/creating-a-tcp-ip-transport-layer-for-external-communication.html#f7917 "Create a Custom Server (Target) Transport Protocol" to modify Target interface to my communication interface on target board. (I use Cortex-M3 Platform).

The problem is when I generate code for my model and add recomended files to my build: matlabroot/rtw/c/src/ext_mode/serial/ext_serial_pkt.c matlabroot/rtw/c/src/ext_mode/serial/rtiostream_serial_interface.c matlabroot/rtw/c/src/ext_mode/serial/ext_svr_serial_transport.c

besides customized transport functions, defined in rtiostream.h file . E.g. rtIOStreamOpen, rtIOStreamClose, rtIOStreamSend,and rtIOStreamRecv, I got the error, that some functions - rtIOStreamBlockingSend and rtIOStreamBlockingRecv are implicit defined. E.g there are no prototypes or definitions available in any file for these functions. What do those functions do? And what I should implement for them?