Undeclared identifiers (C-mex S-Functions) - matlab

Question

I understand that this is a very common problem that a lot is facing. however I don't understand how to link to my program. It's a simple c = a+b program. I have the following as my C-Mex S-function:
#define S_FUNCTION_NAME Addition
#define S_FUNCTION_LEVEL 2
#include "simstruc.h"
static void mdlInitializeSizes(SimStruct *S)
{
int_T nInputPorts = 2; /* Set no. of input ports */
int_T nOutputPorts = 1; /* Set no. of output ports */
int_T needsInput = 1; /* Direct feed through = yes */
int_T inputPortIdx = 0;
int_T outputPortIdx = 0;
ssSetNumSFcnParams(S, 0);
if (ssGetNumSFcnParams(S) != ssGetSFcnParamsCount(S))
{
return; /* If no. of expected input parameters is not equal to no.
of parameters entered in dialog box, return. Simulink
to generate an error indicating parameter mismatched */
}
/* Configure input ports */
if (!ssSetNumInputPorts(S, 2)) return;
/* Configure first input ports */
ssSetInputPortWidth(S, 0, DYNAMICALLY_SIZED); /* Set dimensions of first input port */
ssSetInputPortDirectFeedThrough(S, 0, 1); /* Set direct feed through */
/* Configure second input ports */
ssSetInputPortWidth(S, 1, DYNAMICALLY_SIZED); /* Set dimensions of second input port */
ssSetInputPortDirectFeedThrough(S, 1, 1); /* Set direct feed through */
/* Configure output ports */
if (!ssSetNumOutputPorts(S,1)) return;
ssSetOutputPortWidth(S, 0, DYNAMICALLY_SIZED); /* Set dimensions of output ports */
ssSetNumSampleTimes(S, 1); /* Set no. of sample times */
ssSetSimStateCompliance(S, USE_DEFAULT_SIM_STATE);
ssSetOptions (S,0);
} /* End of mdlInitializeSizes */
static void mdlInitializeSampleTimes (SimStruc *S)
{
ssSetSampleTimes(S, 0, INHERITED_SAMPLE_TIME);
/* Inherited Sample time: S-function block executes whenever driving block executes */
ssSetOffsetTime(S, 0, 0.0); /* No offset required */
ssSetModelReferenceSampleTimeDefaultInheritance(S); /* */
} /* End of mdlInitializeSampleTime */
static void mdlOutputs (SimStruc *S, int_T tid)
{
int_T i;
InputRealPtrsType uPtrs = ssGetInputPortRealSignalPtrs(S,0);
real_T *y = ssGetOutputPortRealSignal(S,0);
int_T width = ssGetOutputPortWidth(S,0);
for (i=0; i<width; i++) /* i = location of memory. from 0 to 1. */
{
*y++ = (*uPtrs[i+1]) + (*uPtrs[i]); /* c = a + b */
}
} /* End of mdlOutputs */
static void mdlTerminate(SimStruct *S)
{
/* No task to be perform at end of simulation therefore no termination required.
But this is a compulsory function to have for C-mex S-function */
} /* End of mdlTerminate */
#ifdef MATLAB_MEX_FILE
#include "simulink.c"
#else
#include "cg_sfun.h"
#endif
however when compiling on matlab, i keep getting the following error:
Addition.c:47: error: expected ‘)’ before ‘*’ token
Addition.c:56: error: expected ‘)’ before ‘*’ token
In file included from Addition.c:82:
/DIST/it/sw/amd64/matlab/r2010b/simulink/include/simulink.c: In function ‘_ProcessMexSfunctionCmdLineCall’:
/DIST/it/sw/amd64/matlab/r2010b/simulink/include/simulink.c:2545: error: ‘mdlInitializeSampleTimes’ undeclared (first use in this function)
/DIST/it/sw/amd64/matlab/r2010b/simulink/include/simulink.c:2545: error: (Each undeclared identifier is reported only once
/DIST/it/sw/amd64/matlab/r2010b/simulink/include/simulink.c:2545: error: for each function it appears in.)
/DIST/it/sw/amd64/matlab/r2010b/simulink/include/simulink.c:2601: error: ‘mdlOutputs’ undeclared (first use in this function)
Any comments will be greatly appreciated!

Answer 1

You misspelled SimStruct in the two lines mentioned at the top of your error message. That error about the parentheses means that the compiler doesn't know that SimStruc is a type, so the * doesn't fit. After that, those two functions aren't defined, so the simulink interface gets upset that it can't find those two required functions in your file.