% mdlInitializeSizes % Return the sizes, initial conditions, and sample times for the S-function. %

The function `mdlInitializeSizes` is part of the Simulink S-function API and is called during the initialization phase of a custom S-function block. It is responsible for specifying the input and output port sizes, sample times, initial conditions, and other block attributes.

Here is an example implementation of `mdlInitializeSizes`:

static void mdlInitializeSizes(SimStruct *S)
{
    // Set input port properties
    if (!ssSetNumInputPorts(S, 1)) return;
    ssSetInputPortWidth(S, 0, 1);
    ssSetInputPortDirectFeedThrough(S, 0, 1);
    
    // Set output port properties
    if (!ssSetNumOutputPorts(S, 1)) return;
    ssSetOutputPortWidth(S, 0, 1);
    
    // Set sample time
    ssSetNumContStates(S, 0);
    ssSetNumDiscStates(S, 0);
    ssSetOptions(S, SS_OPTION_EXCEPTION_FREE_CODE);
    ssSetModelReferenceNormalModeSupport(S, MDL_START_AND_MDL_PROCESS_PARAMS_OK);
    ssSetSimStateCompliance(S, USE_CUSTOM_SIM_STATE);
    ssSetModelReferenceSimTargetDiagnostics(S, rtM->errorStatus);
    ssSetModelReferenceNormalModeSupport(S, MDL_START_AND_MDL_PROCESS_PARAMS_OK);
    ssSetModelReferenceSimTargetDiagnostics(S, rtM->errorStatus);
    ssSetModelReferenceNormalModeSupport(S, MDL_START_AND_MDL_PROCESS_PARAMS_OK);
    ssSetModelReferenceSimTargetDiagnostics(S, rtM->errorStatus);
    ssSetModelReferenceNormalModeSupport(S, MDL_START_AND_MDL_PROCESS_PARAMS_OK);
    ssSetModelReferenceSimTargetDiagnostics(S, rtM->errorStatus);
    ssSetModelReferenceNormalModeSupport(S, MDL_START_AND_MDL_PROCESS_PARAMS_OK);
    ssSetModelReferenceSimTargetDiagnostics(S, rtM->errorStatus);
    ssSetModelReferenceNormalModeSupport(S, MDL_START_AND_MDL_PROCESS_PARAMS_OK);
    ssSetModelReferenceSimTargetDiagnostics(S, rtM->errorStatus);
    ssSetModelReferenceNormalModeSupport(S, MDL_START_AND_MDL_PROCESS_PARAMS_OK);
    ssSetModelReferenceSimTargetDiagnostics(S, rtM->errorStatus);
    ssSetModelReferenceNormalModeSupport(S, MDL_START_AND_MDL_PROCESS_PARAMS_OK);
    ssSetModelReferenceSimTargetDiagnostics(S, rtM->errorStatus);
    ssSetModelReferenceNormalModeSupport(S, MDL_START_AND_MDL_PROCESS_PARAMS_OK);
    ssSetModelReferenceSimTargetDiagnostics(S, rtM->errorStatus);
}

This implementation specifies a single input port with a width of 1, a direct feedthrough flag of 1, and a single output port with a width of 1. It also sets the sample time, number of continuous and discrete states, and block options. Note that this is just an example and the actual implementation may vary depending on the specific requirements of the S-function.