/*  File    : mixedm.c
 *  Abstract:
 *
 *      An example S-function illustrating multiple sample times by implementing
 *         integrator -> ZOH(Ts=1second) -> UnitDelay(Ts=1second) 
 *      with an initial condition of 1.
 *	(e.g. an integrator followed by unit delay operation).
 *
 *      For more details about S-functions, see simulink/src/sfuntmpl_doc.c
 *
 *  Copyright 1990-2000 The MathWorks, Inc.
 *  $Revision: 1.11 $
 */

#define S_FUNCTION_NAME mixedm
#define S_FUNCTION_LEVEL 2

#include "simstruc.h"

#define U(element) (*uPtrs[element])  /* Pointer to Input Port0 */

/*====================*
 * S-function methods *
 *====================*/

/* Function: mdlInitializeSizes ===============================================
 * Abstract:
 *    The sizes information is used by Simulink to determine the S-function
 *    block's characteristics (number of inputs, outputs, states, etc.).
 */
static void mdlInitializeSizes(SimStruct *S)
{
    ssSetNumSFcnParams(S, 0);  /* Number of expected parameters */
    if (ssGetNumSFcnParams(S) != ssGetSFcnParamsCount(S)) {
        return; /* Parameter mismatch will be reported by Simulink */
    }

    ssSetNumContStates(S, 1);
    ssSetNumDiscStates(S, 1);
    ssSetNumRWork(S, 1);  /* for zoh output feeding the delay operator */

    if (!ssSetNumInputPorts(S, 1)) return;
    ssSetInputPortWidth(S, 0, 1);
    ssSetInputPortDirectFeedThrough(S, 0, 1);
    ssSetInputPortSampleTime(S, 0, CONTINUOUS_SAMPLE_TIME);
    ssSetInputPortOffsetTime(S, 0, 0.0);

    if (!ssSetNumOutputPorts(S, 1)) return;
    ssSetOutputPortWidth(S, 0, 1);
    ssSetOutputPortSampleTime(S, 0, 1.0);
    ssSetOutputPortOffsetTime(S, 0, 0.0);

    ssSetNumSampleTimes(S, 2);

    /* Take care when specifying exception free code - see sfuntmpl_doc.c. */
    ssSetOptions(S, (SS_OPTION_EXCEPTION_FREE_CODE |
                     SS_OPTION_PORT_SAMPLE_TIMES_ASSIGNED));

} /* end mdlInitializeSizes */



/* Function: mdlInitializeSampleTimes =========================================
 * Abstract:
 *    Two tasks: One continuous, one with discrete sample time of 1.0.
 */
static void mdlInitializeSampleTimes(SimStruct *S)
{
    ssSetSampleTime(S, 0, CONTINUOUS_SAMPLE_TIME);
    ssSetOffsetTime(S, 0, 0.0);

    ssSetSampleTime(S, 1, 1.0);
    ssSetOffsetTime(S, 1, 0.0);

} /* end mdlInitializeSampleTimes */



#define MDL_INITIALIZE_CONDITIONS
/* Function: mdlInitializeConditions ==========================================
 * Abstract:
 *    Initialize both continuous states to one.
 */
static void mdlInitializeConditions(SimStruct *S)
{
    real_T *xC0 = ssGetContStates(S);
    real_T *xD0 = ssGetRealDiscStates(S);

    xC0[0] = 1.0;
    xD0[0] = 1.0;

} /* end mdlInitializeConditions */



/* Function: mdlOutputs =======================================================
 * Abstract:
 *      y = xD, and update the zoh internal output.
 */
static void mdlOutputs(SimStruct *S, int_T tid)
{
    /* update the internal "zoh" output */
    if (ssIsContinuousTask(S, tid)) {
        if (ssIsSpecialSampleHit(S, 1, 0, tid)) {
            real_T *zoh = ssGetRWork(S);
            real_T *xC  = ssGetContStates(S);
            *zoh = *xC;
        }
    }

    /* y=xD */
    if (ssIsSampleHit(S, 1, tid)) {
        real_T *y   = ssGetOutputPortRealSignal(S,0);
        real_T *xD  = ssGetRealDiscStates(S);
        y[0]=xD[0];
    }


} /* end mdlOutputs */



#define MDL_UPDATE
/* Function: mdlUpdate ======================================================
 * Abstract:
 *      xD = xC
 */
static void mdlUpdate(SimStruct *S, int_T tid)
{
    UNUSED_ARG(tid); /* not used in single tasking mode */

    /* xD=xC */
    if (ssIsSampleHit(S, 1, tid)) {
        real_T *xD = ssGetRealDiscStates(S);
        real_T *zoh = ssGetRWork(S);
        xD[0]=*zoh;
    }

} /* end mdlUpdate */



#define MDL_DERIVATIVES
/* Function: mdlDerivatives =================================================
 * Abstract:
 *      xdot = U
 */
static void mdlDerivatives(SimStruct *S)
{
    real_T            *dx   = ssGetdX(S);
    InputRealPtrsType uPtrs = ssGetInputPortRealSignalPtrs(S,0);

    /* xdot=U */
    dx[0]=U(0);

} /* end mdlDerivatives */



/* Function: mdlTerminate =====================================================
 * Abstract:
 *    No termination needed, but we are required to have this routine.
 */
static void mdlTerminate(SimStruct *S)
{
    UNUSED_ARG(S); /* unused input argument */
}

#ifdef  MATLAB_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