Transcript Computer Engineering I (Part I) - fh

Computer Engineering
Dynamic Link Libraries - DLL'S
Dipl.-Ing. (FH) Christian V. Madritsch
University of Applied Science
Electronics and Equipment Engineering
www.cti.ac.at/rts
Copyright Notice
 All rights reserved. No part of this publication
may be reproduced, stored in a retrieval system
or transmitted, in any form or by any means,
electronic, mechanical, photocopying, recording,
or otherwise, without prior written permission of
the author except for student usage.
 Copyright © 2006 by Christian V. Madritsch
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Outline
 How to create DLL's using MSVC?
 How to use DLL's in MSVC Applications?
 Load-Time Dynamic Linking
 Run-Time Dynamic Linking
 How to create DLL's for Matlab?
 Using DLL's with Matlab
 Creating cpp-DLL's with Matlab
 How to create S-Functions for Simulink?
 How to use DLL's in LabVIEW?
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General
 Dynamic-link libraries (DLL) are modules that
contain functions and data.
 A DLL is loaded at runtime by its calling modules
(.EXE or DLL).
 When a DLL is loaded, it is mapped into the
address space of the calling process.
 DLLs can define two kinds of functions:

Exported functions can be called by other modules.
 Internal functions can only be called from within the
DLL where they are defined.
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Types of Dynamic Linking
 There are two methods for calling a function in a DLL:

In load-time dynamic linking, a module makes explicit calls
to exported DLL functions.
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In run-time dynamic linking, a module uses the
LoadLibrary function to load the DLL at run time.
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This requires you to link the module with the import library for
the DLL.
An import library supplies the system with the information
needed to load the DLL and locate the exported DLL functions
when the application is loaded.
After the DLL is loaded, the module calls the GetProcAddress
function to get the addresses of the exported DLL functions.
The module calls the exported DLL functions using the function
pointers returned by GetProcAddress.
This eliminates the need for an import library.
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DllMain Function (i)

Every DLL must have an entry point. The system calls the entry-point function
whenever processes and threads load or unload the DLL.
BOOL WINAPI DllMain(
HINSTANCE hInstance,
DWORD dwReason,
LPVOID lpReserved);

// handle to DLL module
// reason for calling function
// reserved
dwReason:
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DLL_PROCESS_ATTACH: Indicates that the DLL is being loaded into the virtual
address space of the current process. DLLs can use this opportunity to initialize any
instance data.
DLL_THREAD_ATTACH: Indicates that the current process is creating a new thread.
DLL_THREAD_DETACH: Indicates that a thread is exiting cleanly.
DLL_PROCESS_DETACH: Indicates that the DLL is being unloaded from the virtual
address space of the calling process. The DLL can use this opportunity to free any
thread local data.
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DllMain Function (ii)
#include <windows.h>
BOOL WINAPI DllMain( HINSTANCE hInstance, DWORD dwReason, LPVOID
lpReserved)
{ switch(dwReason)
{
case DLL_PROCESS_ATTACH:
// Initialize once for each new process.
// Return FALSE to fail DLL load.
break;
case DLL_THREAD_ATTACH:
// Do thread-specific initialization.
break;
case DLL_THREAD_DETACH:
// Do thread-specific cleanup.
break;
case DLL_PROCESS_DETACH:
// Perform any necessary cleanup.
break;
}
return TRUE; // Successful DLL_PROCESS_ATTACH.
}
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Exporting Functions and
Import Libraries
 Using the _declspec(dllexport) modifier:
__declspec(dllexport) int Add(int x, int y)
{
return x+y;
}
__declspec(dllexport) int Sub(int x, int y)
{
return x-y;
}
 The import library (.LIB) file contains information the linker
needs to resolve external references to exported DLL
functions, so the system can locate the specified DLL and
exported DLL functions at run time.
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Outline
 How to create DLL's using MSVC?
 How to use DLL's in MSVC Applications?
 Load-Time Dynamic Linking
 Run-Time Dynamic Linking
 How to create DLL's for Matlab?
 Using DLL's with Matlab
 Creating cpp-DLL's with Matlab
 How to create S-Functions for Simulink?
 How to use DLL's in LabVIEW?
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Using Load-Time Dynamic Linking (i)
 Copy .lib-File to the search path of the compiler
 Include .lib-File in Project Settings/Link/Input
 Define import functions or user header-file
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Using Load-Time Dynamic Linking (ii)
#include <windows.h>
#include <iostream.h>
int Add(int x, int y);
int main (void)
{
int x, y = 0;
cout << "Enter x: ";
cin >> x;
cout << "Enter y: ";
cin >> y;
cout << "Result x+y= " << Add(x, y) << endl;
return 0;
}
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Outline
 How to create DLL's using MSVC?
 How to use DLL's in MSVC Applications?
 Load-Time Dynamic Linking
 Run-Time Dynamic Linking
 How to create DLL's for Matlab?
 Using DLL's with Matlab
 Creating cpp-DLL's with Matlab
 How to create S-Functions for Simulink?
 How to use DLL's in LabVIEW?
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Using Run-Time Dynamic Linking (i)
 Create .def-File for the DLL:
LIBRARY
EXPORTS
Add
Sub
dll_01
@1
@2
 Use the following functions to access the DLL:
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LoadLibrary
GetProcAddress
FreeLibrary
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Using Run-Time Dynamic Linking (ii)
#include <windows.h>
#include <iostream.h>
typedef int (*MYPROC)(int, int);
int main (void){
HINSTANCE hinstLib;
MYPROC ProcAdd;
hinstLib = LoadLibrary("dll_01");
if (hinstLib != NULL){
ProcAdd = (MYPROC) GetProcAddress(hinstLib, "Add");
if (ProcAdd != NULL){
int x, y = 0;
cout << "Enter x: ";
cin >> x;
cout << "Enter y: ";
cin >> y;
cout << "Result x+y= " << ProcAdd(x, y) << endl;
}
FreeLibrary(hinstLib);
}
return 0;
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}
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Outline
 How to create DLL's using MSVC?
 How to use DLL's in MSVC Applications?
 Load-Time Dynamic Linking
 Run-Time Dynamic Linking
 How to create DLL's for Matlab?
 Using DLL's with Matlab
 Creating cpp-DLL's with Matlab
 How to create S-Functions for Simulink?
 How to use DLL's in LabVIEW?
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Using DLL's with Matlab
 DLL modifications:
 Create a header-File containing prototypes:
__declspec(dllexport) int Add(int x, int y);
__declspec(dllexport) int Sub(int x, int y);
 Matlab functions:
 loadlibrary
 libfunctions
 libfunctionsview
 libisloaded
 calllib
 unloadlibrary
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Matlab Functions (i)
 loadlibrary:
 To load an external library into MATLAB
loadlibrary(libfile, headerfile)
 libfunctions:
 Return information on functions in external library
 libfunctionsview:
 Create window displaying information on functions in
external library
 libisloaded:
 To determine if external library is loaded
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Matlab Functions (ii)
 calllib:
 Call function in external library
 calllib(libfile, functions, arg1, arg2, ...)
 unloadlibrary:
 To unload an external library from memory
 More information:
 Matlab External Interfaces Reference
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Example
loadlibrary('C:\temp\dll_01.dll', 'c:\temp\dll_01.h')
libfunctions dll_01
libfunctionsview dll_01
a = calllib('dll_01', 'Add', 2, 3)
b = calllib('dll_01', 'Sub', 5, 2)
unloadlibrary('dll_01')
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Outline
 How to create DLL's using MSVC?
 How to use DLL's in MSVC Applications?
 Load-Time Dynamic Linking
 Run-Time Dynamic Linking
 How to create DLL's for Matlab?
 Using DLL's with Matlab
 Creating cpp-DLL's with Matlab
 How to create S-Functions for Simulink?
 How to use DLL's in LabVIEW?
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Creating cpp-DLL's with Matlab
 cpp-File:
 The entry point is called mexFunction
void mexFunction(int nlhs, mxArray *plhs[],
int nrhs, const mxArray *prhs[])

nlhs: number of left-handed side arguments
 plhs: pointer to array of left-handed side arguments
 nrhs: number of right-handed side arguments
 prhs: pointer to array of right-handed side arguments
 [a, b, c, ...] = function(d, e, f, ...)
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Example
#include "mex.h"
int Add(double x[], double y[]){
return x[0]+y[0];
}
void mexFunction(int nlhs,mxArray *plhs[],int nrhs,const mxArray *prhs[])
{
double *x, *y, *res;
if(nrhs < 2){
mexPrintf("Too few arguments!");
return;}
if(nlhs > 1){
mexPrintf("Too many outputs!");
return;}
x = mxGetPr(prhs[0]);
y = mxGetPr(prhs[1]);
plhs[0] = mxCreateDoubleMatrix(1,1, mxREAL);
res = mxGetPr(plhs[0]);
res[0] = Add(x, y);
}
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How to compile?
 mex -setup

Adjust Microsoft Compiler
 mex add.app
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Compiles add.cpp File into Matlab DLL
 More information:
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Matlab External Interfaces Reference
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Outline
 How to create DLL's using MSVC?
 How to use DLL's in MSVC Applications?
 Load-Time Dynamic Linking
 Run-Time Dynamic Linking
 How to create DLL's for Matlab?
 Using DLL's with Matlab
 Creating cpp-DLL's with Matlab
 How to create S-Functions for Simulink?
 How to use DLL's in LabVIEW?
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S-Functions for Simulink
 A S-function is a computer language description of a Simulink
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block.
 S-functions can be written in MATLAB, C, C++, Ada, or
Fortran.
C, C++, Ada, and Fortran S-functions are compiled as MEXfiles using the mex utility.
As with other MEX-files, they are dynamically linked into
MATLAB when needed.
S-functions allow you to add your own blocks to Simulink
models.
More information:
 Simulink: Writing S-Functions
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S-Functions Structure
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Sample Code (i)
#define S_FUNCTION_NAME add
#define S_FUNCTION_LEVEL 2
#include "simstruc.h"
static void mdlInitializeSizes(SimStruct *S){
ssSetNumSFcnParams(S, 0);
if (ssGetNumSFcnParams(S) != ssGetSFcnParamsCount(S))
return;
if (!ssSetNumInputPorts(S, 2))
return;
ssSetInputPortWidth(S, 0, DYNAMICALLY_SIZED );
ssSetInputPortDataType(S, 0, DYNAMICALLY_TYPED );
ssSetInputPortDirectFeedThrough(S, 0, 1 );
ssSetInputPortWidth(S, 1, DYNAMICALLY_SIZED );
ssSetInputPortDataType(S, 1, DYNAMICALLY_TYPED );
ssSetInputPortDirectFeedThrough(S, 1, 1 );
if (!ssSetNumOutputPorts(S, 1))
return;
ssSetOutputPortWidth(S, 0, DYNAMICALLY_SIZED );
ssSetOutputPortDataType(S, 0, DYNAMICALLY_TYPED );
ssSetNumSampleTimes(S, 1);
ssSetOptions(S,SS_OPTION_WORKS_WITH_CODE_REUSE | SS_OPTION_EXCEPTION_FREE_CODE);
}
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Sample Code (ii)
static void mdlInitializeSampleTimes(SimStruct *S)
{
ssSetSampleTime(S, 0, INHERITED_SAMPLE_TIME);
ssSetOffsetTime(S, 0, 0.0);
}
static void mdlOutputs(SimStruct *S, int_T tid)
{
InputRealPtrsType x = ssGetInputPortRealSignalPtrs(S,0);
InputRealPtrsType y = ssGetInputPortRealSignalPtrs(S,1);
real_T *ergebnis
= ssGetOutputPortRealSignal(S,0);
*ergebnis = *x[0] + *y[0];
}
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Sample Code (iii)
static void mdlTerminate(SimStruct *S)
{
}
/*=============================*
* Required S-function trailer *
*=============================*/
#ifdef MATLAB_MEX_FILE
#include "simulink.c"
#else
#include "cg_sfun.h"
#endif
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Include S-Functions to Simulink (i)
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Include S-Functions to Simulink (ii)
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Outline
 How to create DLL's using MSVC?
 How to use DLL's in MSVC Applications?
 Load-Time Dynamic Linking
 Run-Time Dynamic Linking
 How to create DLL's for Matlab?
 Using DLL's with Matlab
 Creating cpp-DLL's with Matlab
 How to create S-Functions for Simulink?
 How to use DLL's in LabVIEW?
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Including DLL's in LabVIEW
 Select:

Connectivity/Libraries&Executables function palette
 Select:

Call Library Function Node and place
it on diagram
 Double-Click LFN on diagram
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Configuring
 Enter Library or Path Name
 Select Function Name
 Select Return Type
 Add Parameters
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Calling the function
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