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Michal Princ (nxa17570) edited this page Apr 17, 2020 · 8 revisions

This chapter is about creating simple eRPC client/server application. From the eRPC point of view, creating an application contains two steps:

  • Generating and importing eRPC shim code.
  • Import eRPC common files and call functions to init environment.

An application demo is shown on the matrix multiplication client/server baremetal application, which is using UART transport.

Generating and importing eRPC shim code

This chapter contains three topics. First, IDL file needs be created. Use this file for generating shim code. Finally, the client application needs to import client-relevant files, and server needs to import server-relevant files.

Creating IDL file

IDL files contains all declarations used in eRPC calls. Simple example can looks like.

IDL.erpc:

/*!
 * You can write copyrights rules here. These rules will be copied into the outputs.
 */
@outputDir("erpc_outputs") // output directory
program erpc_matrix_multiply; // specify name of output files

/*! This const defines the matrix size. The value has to be the same as the
    Matrix array dimension. Do not forget to re-generate the eRPC code once the
    matrix size is changed in the eRPC file */
const int32 matrix_size = 5;

/*! This is the matrix array type. The dimension has to be the same as the
    matrix size const. Do not forget to re-generate the eRPC code once the
    matrix size is changed in the eRPC file */
type Matrix = int32[matrix_size][matrix_size];

interface MatrixMultiplyService // cover functions for same topic
{
    erpcMatrixMultiply(in Matrix matrix1, in Matrix matrix2, out Matrix result_matrix) -> void
}

This function sends two matrices from client to server and one matrix with results are sent back.

Generating shim code

For generating shim code is needed two things:

  • eRPC generator tool - See erpcgen documentation section.
  • IDL file - Created in previous topic.

The easiest way for generating code is have both the tool and the IDL file in same directory. Then, the following command needs be executed:

erpcgen.exe IDL.erpc

This action creates four files in erpc_outputs folder:

  • erpc_matrix_multiply.h
  • erpc_matrix_multiply_client.cpp
  • erpc_matrix_multiply_server.h
  • erpc_matrix_multiply_server.cpp

Importing client/server files

Client project needs to count with erpc_matrix_multiply.h and erpc_matrix_multiply_client.cpp files. In the source file where the eRPC functions are called, the erpc_matrix_multiply.h header file needs to be included.

Server project needs to count with erpc_matrix_multiply.h, erpc_matrix_multiply_server.h, and erpc_matrix_multiply_server.cpp files. In source file where eRPC functions calls are implemented, the erpc_matrix_multiply_server.h header file needs to be included.

Import eRPC common files and call functions to the init environment.

This chapter contains three topics:

  • Common contains information which common files needs be imported for the client and server application.
  • Client contains information which client files needs be imported for the client and server application.
  • Server contains information which server files needs be imported for the client and server application.

Common

The basic rule is that files do not contain "client" or "server" string in their names. These files need the server and client application:

  • From ERPCRootDir/erpc_c/config file erpc_config.h. This file should be copied to application specific directory and used it instead of using this global file.
  • From ERPCRootDir/erpc_c/infra files erpc_codec.h, erpc_basic_codec.h, erpc_basic_codec.cpp, erpc_common.h, erpc_version.h, erpc_framed_transport.h, erpc_framed_transport.cpp, erpc_manually_constructed.h, erpc_message_buffer.h erpc_transport.h and erpc_message_buffer.cpp
  • From ERPCRootDir/erpc_c/port files erpc_config_internal.h, erpc_port.h and erpc_port_stdlib.cpp
  • From ERPCRootDir/erpc_c/setup files erpc_mbf_setup.h, erpc_setup_mbf_dynamic.cpp, erpc_transport_setup.h and erpc_setup_uart_cmsis.cpp
  • From ERPCRootDir/erpc_c/transports files erpc_uart_cmsis_transport.h and erpc_uart_cmsis_transport.cpp

Client

The basic rule is client files contains "client" string in their names.

  • From ERPCRootDir/erpc_c/infra files erpc_client_manager.h and erpc_client_manager.cpp
  • From ERPCRootDir/erpc_c/setup files erpc_client_setup.h and erpc_client_setup.cpp

In source file where eRPC client environment init functions are called needs be included erpc_client_setup.h header file.

Server

The basic rule is client files contains "server" string in their names.

  • From ERPCRootDir/erpc_c/infra files erpc_server.h, erpc_server.cpp, erpc_simple_server.h and erpc_simple_server.cpp
  • From _ERPCRootDir/erpc_c/setup files erpc_server_setup.h and erpc_server_setup.cpp

In the source file where the eRPC server environment init functions are called, the erpc_server_setup.h header file needs to be included.

Example of client/server main files.

This chapter shows the easiest main source file for the client and server side.

Client main file

#include "erpc_matrix_multiply.h"
#include "erpc_client_setup.h"
#include "fsl_uart_cmsis.h" /* Not an eRPC file. Needs to be replaced with the included transport type. */

int main()
{
    /* Matrices definitions */
    Matrix matrix1, matrix2, result_matrix = {{0}};

    /* Init eRPC client environment */
    /* UART transport layer initialization */
    erpc_transport_t transport = erpc_transport_cmsis_uart_init((void *)&DEMO_UART); /* DEMO_UART defined in fsl_uart_cmsis.h */

    /* MessageBufferFactory initialization */
    erpc_mbf_t message_buffer_factory = erpc_mbf_dynamic_init();

    /* eRPC client side initialization */
    erpc_client_init(transport, message_buffer_factory);

    /* other code like init matrix1 and matrix2 values */
    ...

    /* call eRPC functions */
    erpcMatrixMultiply(matrix1, matrix2, result_matrix);

    /* other code like print result matrix */
    ...

    return 0;
}

Server main file

#include "erpc_matrix_multiply_server.h"
#include "erpc_server_setup.h"
#include "fsl_uart_cmsis.h" /* Not eRPC file. Need be replaced with include of transport type. */

/* implementation of function call */
void erpcMatrixMultiply(Matrix matrix1, Matrix matrix2, Matrix result_matrix)
{
    /* code for multiplication of matrices */
    ...
}

int main()
{
    /* Init eRPC server environment */
    /* UART transport layer initialization */
    erpc_transport_t transport = erpc_transport_cmsis_uart_init((void *)&DEMO_UART); /* DEMO_UART defined in fsl_uart_cmsis.h */

    /* MessageBufferFactory initialization */
    erpc_mbf_t message_buffer_factory = erpc_mbf_dynamic_init();

    /* eRPC server side initialization */
    erpc_server_init(transport, message_buffer_factory);

    /* connect generated service into server, look into erpc_matrix_multiply_server.h */
    erpc_service_t service = create_MatrixMultiplyService_service();
    erpc_add_service_to_server(service);

    /* run server */
    erpc_server_run(); /* or erpc_server_poll(); */

    return 0;
}

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