MATLAB: Mex file compiling error

c file s-functionmex compiler

I want to create mex file but the compiler give this error..

1. Error ForceSensor.c: 121 undeclared identifier `USE_DEFAULT_SIM_STATE' 2. Warning ForceSensor.c: 121 possible usage of USE_DEFAULT_SIM_STATE before definition 1 errors, 1 warnings

anybody could help

Best Answer

Is this an S-function? If yes, you are probably missing:

   #include "simstruc.h"

Related Solutions

MATLAB: How to allocate and free memory for a PWork vector in a C-MEX S-function

First, the S-Function needs to specify how many PWork vectors it needs (using ssSetNumPWork) either in mdlInitializeSizes or in mdlSetWorkWidths. Simulink calls the above functions in the S-Function at the beginning of the model initialization stage (internally we refer to this part of the initialization stage as the compile phase). Towards the end of model initialization stage (internally we refer to this part of the initialization stage as the link phase), Simulink allocates the specified number of PWorks. Upon completing the model initialization stage, Simulink calls the S-Function's mdlStart. In the mdlStart function, the S-Function can allocate memory and store a pointer to it in the PWork array. The following code snippet illustrates specifying, allocating, using, and freeing memory using PWorks.

mdlInitializeSizes(SimStruct* S) 
{ 
/* snip */
ssSetNumPWork(S, 1);
/* snip */ 
}
mdlStart(SimStruct* S) 
{ 
/* snip */
void* ptr = malloc(1024 /* number of bytes */); 
if (ptr == NULL) { 
/* report memory allocation error */ 
ssSetErrorStatus(S, "Memory allocation error"); 
return; 
} 
ssSetPWorkValue(S, 0, ptr);
/* snip */ 
}
mdlOutputs(SimStruct* S, int_T tid) 
{ 
void* ptr = ssGetPWorkValue(S, 0);
/* snip */ 
}
mdlTerminate(SimStruct* S) 
{ 
/* snip */
/* free the memory allocated in mdlStart */ 
if (ssGetPWork(S) != NULL) { 
void* ptr = ssGetPWorkVale(S,0); 
if (ptr != NULL) free(ptr); 
}
/* snip */ 
}

For a more complete example on using PWork vectors please look at the following example in the documentation.

http://www.mathworks.com/help/releases/R2009b/toolbox/simulink/sfg/bre1pj2.html#bre1ps0

MATLAB: Can I create a C++ MEX-file S-function

We officially support C++ MEX-file S-functions as of Simulink 4.0 (R12).

To view an example of how to do this, please type:

sfundemos

at the MATLAB Command Prompt. This will open sfundemos.mdl. This demo that ships with SIMULINK provides examples of how to write different types of S-Functions and includes a C++ example.

You can also take a look at chapter 4 of the "Writing S-function" manual which has a good description on writing C++ MEX-file S-functions.

When writing the S-function, declare the MEX Function as extern "C". The rest of the code that you write can all be in C++. For example:

 extern "C" 
 {
 void mexFunction(
     int nlhs_,
     mxArray *plhs_[],
     int nrhs_,
     const mxArray *prhs_[])
 {
   /* Body can use all C++ language features and file can be compiled with a
      C++ compiler
    */
 }
 }

Below is the 'Timestwo' example written as a C++ file. You can compile the file using the MEX command. Note that if you are using the Watcom compiler, you need to add the -DNO_BUILT_IN_SUPPORT_FOR_BOOL flag to your COMPFLAGS option in your options file.

If you are using MSVC 5.0, you do not need to add this flag. The C compiler will automatically know to compile it as C++ code using the mex command.

 /*
* TIMESTWO An example C-file S-function for multiplying an input by 2
*      
*      y  = 2*x
*   
*   See sfuntmpl.c for a general S-function template.
*
*   See also VSFUNC, DSFUNC, SFUNTMPL.
* 
*   Copyright (c) 1990-96 by MathWorks, Inc.
*   All Rights Reserved
*   $Revision: 1.1 $
*/
 #ifdef __cplusplus
     extern "C" {
 #endif
 #define S_FUNCTION_NAME timestwo_level1_cpp
 /* The following three lines are necessary for the WATCOM compiler
* only. You need to remove these lines for the MSVC compiler.
*/
 #ifndef COMPILER_SUPPORTS_BOOL
 typedef int bool;
 #endif
 #include "simstruc.h"
 /*
* mdlInitializeSizes - initialize the sizes array
*/
 static void mdlInitializeSizes(SimStruct *S)
 {
     ssSetNumContStates(    S, 0);   /* number of continuous states */
     ssSetNumDiscStates(    S, 0);   /* number of discrete states */
     ssSetNumInputs(        S, DYNAMICALLY_SIZED);   /* number of inputs */
     ssSetNumOutputs(       S, DYNAMICALLY_SIZED);   /* number of outputs */
     ssSetDirectFeedThrough(S, 1);   /* direct feedthrough flag */
     ssSetNumSampleTimes(   S, 1);   /* number of sample times */
     ssSetNumSFcnParams(    S, 0);   /* number of input arguments */
     ssSetNumRWork(         S, 0);   /* number of real work vector elements */
     ssSetNumIWork(         S, 0);   /* number of integer work vector elements */
     ssSetNumPWork(         S, 0);   /* number of pointer work vector elements */
 }
 /*
* mdlInitializeSampleTimes - initialize the sample times array
*/
 static void mdlInitializeSampleTimes(SimStruct *S)
 {
     ssSetSampleTime(S, 0, CONTINUOUS_SAMPLE_TIME);
     ssSetOffsetTime(S, 0, 0.0);
 }
 /*
* mdlInitializeConditions - initialize the states
*/
 static void mdlInitializeConditions(double *x0, SimStruct *S)
 {
 }
 /*
* mdlOutputs - compute the outputs
*/
 static void mdlOutputs(double *y, double *x, double *u, SimStruct *S, int tid)
 {
     class mul2 {
         double            *u;
         double            *y;
         int                width;
     public:
         mul2(double *u_i, double *y_i, int width_i) 
         {
             u = u_i;
             y = y_i;
             width = width_i;
         }
         void output(void) 
         {
             for (int i=0;i<width;i++)
             { 
                 *y++=2.0*(*u++); 
             }
         }
     };
     class mul2 m(u,y,ssGetNumOutputs(S));
     m.output();
 }
 /*
* mdlUpdate - perform action at major integration time step
*/
 static void mdlUpdate(double *x, double *u, SimStruct *S, int tid)
 {
 }
 /*
* mdlDerivatives - compute the derivatives
*/
 static void mdlDerivatives(double *dx, double *x, 
                            double *u, SimStruct *S, int tid)
 {
 }
 /*
* mdlTerminate - called when the simulation is terminated.
*/
 static void mdlTerminate(SimStruct *S)
 {
 }
 #ifdefMATLAB_MEX_FILE    /* Is this file being compiled as a MEX-file? */
 #include "simulink.c"      /* MEX-file interface mechanism */
 #else
 #include "cg_sfun.h"       /* Code generation registration function */
 #endif
 #ifdef __cplusplus
     }
 #endif

Best Answer

Related Solutions

MATLAB: How to allocate and free memory for a PWork vector in a C-MEX S-function

MATLAB: Can I create a C++ MEX-file S-function

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