schdint.c

数字通信第四版原书的例程

/*
 * SCHDINT   A SIMULINK scheduling integration
 *
 *           Syntax:  [sys, x0] = schdint(t, x, u, flag, TD, TS, Modulo)
 *
 *      This block will reset the integration to be zero at K*TD(1) + TD(2).
 *      TS: sampling time of the integration. This is a discrete-time block.
 *      Modulo: Limitation of the integration. When State is larger than this
 *              value it will do x=rem(x,Modulo) computation.
 *
 * Wes Wang Dec. 8, 1994
 * Copyright (c) 1994 by The MathWorks, Inc.
 * All Rights Reserved
 */

#define S_FUNCTION_NAME schdint

#include <math.h>     /* needed for declaration of sprintf */

#ifdef MATLAB_MEX_FILE
#include <stdio.h>    /* needed for declaration of sprintf */
#include "mex.h"      /* needed for declaration of mexErrMsgTxt */
#endif

/*
 * need to include simstruc.h for the definition of the SimStruct and
 * its associated macro definitions.
 */

#include "simstruc.h"

/*
 * Defines for easy access of the input parameters
 */

#define NUM_ARGS  3
#define TD     ssGetArg(S,0)
#define TS ssGetArg(S,1)
#define Modulo     ssGetArg(S,2)

/*
 * mdlInitializeSizes - called to initialize the sizes array stored in
 *                      the SimStruct.  The sizes array defines the
 *                      characteristics (number of inputs, outputs,
 *                      states, etc.) of the S-Function.
 */

static void mdlInitializeSizes(S)
    SimStruct *S;
{
    /*
     * Set-up size information.
     */ 
    
    if (ssGetNumArgs(S) == NUM_ARGS) {
      int in_length, num_points;
    char method[2];
    double mod_bound;

    mod_bound = mxGetPr(Modulo)[0];
	
   if ((mxGetN(TD)*mxGetM(TD) != 1) &&
         (mxGetN(TD)*mxGetM(TD) != 2)) {
#ifdef MATLAB_MEX_FILE
           mexErrMsgTxt("The reset time must be a scalar or a vector of length 2");
#endif
      }
       if ((mxGetN(TS)*mxGetM(TS) != 1) &&
         (mxGetN(TS)*mxGetM(TS) != 2)) {
#ifdef MATLAB_MEX_FILE
           mexErrMsgTxt("The sample time must be a scalar or a vector of length 2");
#endif
     }
       if (mxGetN(Modulo)*mxGetM(Modulo) != 1) {
#ifdef MATLAB_MEX_FILE
     mexErrMsgTxt("The modulo number can be an scalar only.");
#endif
     }
       if (mod_bound <= 0) {
#ifdef MATLAB_MEX_FILE
         mexErrMsgTxt("The modulo number can be positive number only.");
#endif
       }           

    ssSetNumContStates(    S, 0);
   ssSetNumDiscStates(    S, -1);
  ssSetNumInputs(        S, -1);
  ssSetNumOutputs(       S, -1);
          ssSetDirectFeedThrough(S, 0);
   ssSetNumInputArgs(     S, NUM_ARGS);
   if (mxGetPr(TD)[0] > 1.e30) {
       ssSetNumSampleTimes(   S, 1);
   } else {
       ssSetNumSampleTimes(   S, 2);
   }
#if defined(applec)
       ssSetNumSampleTimes(   S, 1);
#endif   	   
   ssSetNumRWork(         S, 2);
   ssSetNumIWork(         S, 1);
   ssSetNumPWork(         S, 0);
    } else {
#ifdef MATLAB_MEX_FILE
 char err_msg[256];
      sprintf(err_msg, "Wrong number of input arguments passed to S-function MEX-file.\n"
             "%d input arguments were passed in when expecting %d input arguments.\n", ssGetNumArgs(S) + 4, NUM_ARGS + 4);
   mexErrMsgTxt(err_msg);
#endif
    }
}

/*
 * mdlInitializeSampleTimes - initializes the array of sample times stored in
 *                            the SimStruct associated with this S-Function.
 */

static void mdlInitializeSampleTimes(S)
    SimStruct *S;
{
    double sampleTime, offsetTime;

    /*
     * Note, blocks that are continuous in nature should have a single
     * sample time of 0.0.
     */
 
    sampleTime = mxGetPr(TS)[0];
    if ((mxGetN(TS) * mxGetM(TS)) == 2)
           offsetTime = mxGetPr(TS)[1];
    else
            offsetTime = 0.;
    
    ssSetSampleTimeEvent(S, 0, sampleTime);
    ssSetOffsetTimeEvent(S, 0, offsetTime);   
 	
#if defined(applec)

#else
    sampleTime = mxGetPr(TD)[0];
    if (sampleTime <= 1.e30) {
        if ((mxGetN(TD) * mxGetM(TD)) == 2)
           offsetTime = mxGetPr(TD)[1];
        else
           offsetTime = 0.;
        ssSetSampleTimeEvent(S, 1, sampleTime);
        ssSetOffsetTimeEvent(S, 1, offsetTime);
    }
#endif
}

/*
 * mdlInitializeConditions - initializes the states for the S-Function
 */

static void mdlInitializeConditions(x0, S)
    double *x0;
    SimStruct *S;
{
    double *current_drive_time  = ssGetRWork(S);
    double *last_time = ssGetRWork(S) + 1;
    double sampleTime;
    int    *hitted_num = ssGetIWork(S);
    int in_length = ssGetNumInputs(S);
    int i;

    if (ssGetT(S) <= 0) {
        sampleTime = mxGetPr(TS)[0];    
        /*take the following number instead of 0 to avoid additive error for miss hitting*/
        *current_drive_time = 0.0;
        *last_time = ssGetT(S)-sampleTime;
        *hitted_num = 0;
        for (i=0; i<in_length; i++)
            x0[i] = 0.0;
    }
}

/*
 * mdlOutputs - computes the outputs of the S-Function
 */

static void mdlOutputs(y, x, u, S, tid)
    double *y, *x, *u;
    SimStruct *S;
    int tid;
{
    int in_length = ssGetNumInputs(S);
    int i;
    for (i=0; i<in_length;i++)
        y[i] = x[i];
}

/*
 * mdlUpdate - computes the discrete states of the S-Function
 */

static void mdlUpdate(x, u, S, tid)
    double *x, *u;
    SimStruct *S;
    int tid;
{
    double *current_drive_time  = ssGetRWork(S);
    double *last_time = ssGetRWork(S) + 1;
    double current_time = ssGetT(S);
    double sampleTime, offsetTime, time_step, it_time;

    int    *hitted_num = ssGetIWork(S);    
    int in_length = ssGetNumInputs(S);
    int i;

    it_time = mxGetPr(TS)[0];    
    sampleTime = mxGetPr(TD)[0];
    if ((mxGetN(TD) * mxGetM(TD)) == 2)
       offsetTime = mxGetPr(TD)[1];
    else
       offsetTime = 0.;

    /* calculation only if the time is passed offset time. */
#ifdef MATLAB_MEX_FILE
 	if (0) {
	    char err_msg[256];
        sprintf(err_msg, "offsetTime %f, Current_time %f, Sample_time %f\n", offsetTime, current_time, sampleTime);
        mexPrintf(err_msg);        
	}
#endif
    if (current_time >= offsetTime) {
        int itmp;
        double mod_bound;

      
        mod_bound = mxGetPr(Modulo)[0];
        time_step = current_time - (*last_time);
        time_step = time_step < it_time ? time_step : it_time;
        *current_drive_time += time_step;
#ifdef MATLAB_MEX_FILE
        if (0) {
	   char err_msg[256];
           sprintf(err_msg, "Current_drive_time %f, Current_time %f, Sample_time %f, hitted_num %i, offsetTime %f\n", *current_drive_time, current_time, sampleTime, *hitted_num, offsetTime);
           mexPrintf(err_msg);        
	}
#endif
        if ((*current_drive_time >= sampleTime) || ((*hitted_num>0) && (current_time >= (double)(*hitted_num) * sampleTime + offsetTime))){
            /*reset*/
            for (i=0; i<in_length; i++) {
#ifdef MATLAB_MEX_FILE
                if (0) {
	            char err_msg[256];
                    sprintf(err_msg, "x %f, time_step %f\n", x[i], time_step);
                    mexPrintf(err_msg);                        
                }
#endif
                x[i] = u[i] * time_step;
                x[i] = fmod(x[i], mod_bound);               
           }
            *hitted_num += 1;
            /*take the following number instead of 0 to avoid additive error for miss hitting*/
            *current_drive_time = sampleTime/1000000000;
        } else {
            for (i=0; i<in_length; i++) {
#ifdef MATLAB_MEX_FILE
	        if (0) {
	            char err_msg[256];
                    sprintf(err_msg, "ELSE x %f, time_step %f\n", x[i], time_step);
                    mexPrintf(err_msg);                                        
                }
#endif
                x[i] += u[i] * time_step;
                x[i] = fmod(x[i], mod_bound); 
            }
        }
    }
    if (current_time > *last_time)
        *last_time = current_time;
}

/*
 * mdlDerivatives - computes the derivatives of the S-Function
 */

static void mdlDerivatives(dx, x, u, S, tid)
    double *dx, *x, *u;
    SimStruct *S;
    int tid;
{
}

/*
 * mdlTerminate - called at termination of model execution.
 */

static void mdlTerminate(S)
    SimStruct *S;
{
}

#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