source: vis_dev/vis-2.3/src/sim/simIo.c @ 40

/**CFile***********************************************************************

  FileName    [simIo.c]

  PackageName [sim]

  Synopsis    [Routines to read and write simulation vectors.]

  Author      [Shaker Sarwary, Tom Shiple and Rajeev Ranjan]

  Copyright   [Copyright (c) 1994-1996 The Regents of the Univ. of California.
  All rights reserved.

  Permission is hereby granted, without written agreement and without license
  or royalty fees, to use, copy, modify, and distribute this software and its
  documentation for any purpose, provided that the above copyright notice and
  the following two paragraphs appear in all copies of this software.

  IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
  DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
  OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
  CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

  THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
  INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS ON AN
  "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO PROVIDE
  MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.]

******************************************************************************/
#include "simInt.h"

static char rcsid[] UNUSED = "$Id: simIo.c,v 1.5 2005/05/10 15:50:43 hhkim Exp $";

/*---------------------------------------------------------------------------*/
/* Constant declarations                                                     */
/*---------------------------------------------------------------------------*/

/*
 * Maximum permissible length of a line in the simulation file.
 */
#define MAX_LINE_LENGTH 500000


/**AutomaticStart*************************************************************/

/*---------------------------------------------------------------------------*/
/* Static function prototypes                                                */
/*---------------------------------------------------------------------------*/

static array_t * SimObtainInputsArray(Sim_Sim_t * sim);
static void FreeArrays(array_t *array1, array_t *array2, array_t *array3, array_t *array4);
static array_t * BufferBuildInputsNodeArray(char * buffer, Ntk_Network_t * network);
static array_t * BufferBuildLatchesNodeArray(char * buffer, Ntk_Network_t * network);
static array_t * BufferBuildOutputsNodeArray(char * buffer, Ntk_Network_t * network);
static array_t * BufferBuildValuesArray(char * buffer, array_t * nodesArray);
static void SimAddVector(Sim_Sim_t * sim, array_t * vector);
static void BufferSkipWhiteSpace(char * buffer, int * position);
static char * BufferObtainStringAtPosition(char * buffer, int * position);
static void PrintValue(array_t *nodesArray, array_t *vector, int vectorIndex, int strSize, FILE *file);

/**AutomaticEnd***************************************************************/


/*---------------------------------------------------------------------------*/
/* Definition of exported functions                                          */
/*---------------------------------------------------------------------------*/

/**Function********************************************************************

  Synopsis    [Print the simulation vectors contained in a SimSimStruct.]

  Description [Print the simulation vectors contained in a SimSimStruct. If
  printMode is 0, then only vectors are printed, else the header is also
  printed(.inputs, .outputs ...). printInputsFlag,
  printPseudoInputsFlag, printOutputsFlag, and printStatesFlag control
  the printing of primary inputs, pseudo inputs, primary outputs and
  state variables respectively. A value of 1 of these flags indicate
  printing is enabled, and value 0 indicates otherwise.  This function writes
  warnings into error_string. The printed file is accepted as input file in sim.]

  SideEffects []

******************************************************************************/
void
Sim_SimPrint(
  Sim_Sim_t       * sim,
  FILE            * of,
  boolean         printMode,
  int             printInputsFlag,
  int             printOutputsFlag,
  int             printPseudoInputsFlag,
  int             printStatesFlag
  )

{
  int             i, j;
  char           *str;
  array_t        *vector = NIL(array_t);
  array_t        *formatArray;
  Ntk_Node_t     *node;
  Var_Variable_t *var;
  int             index;
  int             strSize     = 0;
  int             numNodes    = array_n(sim->nodesArray);  
  int             inputWidth  = sim->currentStateHead;

  if(sim->verbose) {
    (void) printf("Printing %d vectors...\n", array_n(sim->vectorArray));
  }
  
  formatArray = SimSimInitDataFormat(sim);
  
  if (printMode) {
    (void) fprintf(of, "# %s\n", Vm_VisReadVersion());
    (void) fprintf(of, "# Network: %s\n", Ntk_NetworkReadName(sim->network));

    if (sim->inputFile != NIL(char)) {
      (void) fprintf(of, "# Input Vectors File: %s\n", sim->inputFile);
    }
    else {
      (void) fprintf(of, "# Simulation vectors have been randomly generated\n");
    }
    (void) fprintf(of, "\n\n");
    (void) fprintf(of, ".inputs  ");
    for (i = 0; i < inputWidth; i++) {
      node = array_fetch(Ntk_Node_t *, sim->nodesArray, i);
      (void) fprintf(of, "%s ", Ntk_NodeReadName(node));
    }
    (void) fprintf(of, "\n");
    (void) fprintf(of, ".latches ");
    for (i = sim->currentStateHead; i < sim->internalPartitionHead; i++) {
      node = array_fetch(Ntk_Node_t *, sim->nodesArray, i);
      (void) fprintf(of, "%s ", Ntk_NodeReadName(node));
    }
    (void) fprintf(of, "\n");

    (void) fprintf(of, ".outputs ");
    for (i = sim->outputHead; i < numNodes; i++) {
      node = array_fetch(Ntk_Node_t *, sim->nodesArray, i);
      (void) fprintf(of, "%s ", Ntk_NodeReadName(node));
    }
    (void) fprintf(of, "\n");

    /* Reset State is the current state of the first vector */
    (void) fprintf(of, ".initial ");
    vector = array_fetch(array_t *, sim->vectorArray, 0);
    for (i = sim->currentStateHead; i < sim->internalPartitionHead; i++) {
      if(i >= array_n(vector)) {/* If currentState is not specified '*' is printed */
        (void) fprintf(of, "* ");
      }
      else {
        node = array_fetch(Ntk_Node_t *, sim->nodesArray, i);
        var = Ntk_NodeReadVariable(node);
        index = array_fetch(int, vector, i);
        if (Var_VariableTestIsSymbolic(var)) {
          (void) fprintf(of, "%s ", Var_VariableReadSymbolicValueFromIndex(var, index));
        }
        else { /* Binary or enumerative type */
          str = SimInteger2ASCII(index);
          (void) fprintf(of, "%s ", str);
          FREE(str);
        }
      }
    }
    
    (void) fprintf(of, "\n\n.start_vectors");

    (void) fprintf(of, "\n\n");

    /*
     * Print the order of variables for which values
     * are printed in the next lines.
     */
    
    (void) fprintf(of, "# ");
    /*
     * If either printInputsFlag or printPseudoInputsFlag is zero, we
     * cannot use the output as the input for simulation. Print a
     * warning message regarding that.
     */
    if ((printInputsFlag == 0) || (printPseudoInputsFlag == 0)){
      (void) fprintf(vis_stderr,"Warning - print flag of some inputs is set to zero.\n");
      (void) fprintf(vis_stderr,"Hence the output file you specified cannot be used as an input\n");
      (void) fprintf(vis_stderr,"file for a subsequent simulation run.\n");
    }
      
    if (printInputsFlag || printPseudoInputsFlag){
      for (i = 0; i < inputWidth; i++) {
        node = array_fetch(Ntk_Node_t *, sim->nodesArray, i);
        if (Ntk_NodeTestIsPrimaryInput(node)){
          if (printInputsFlag){
            (void) fprintf(of, "%s ", Ntk_NodeReadName(node));
          }
        }
        else{
          if (printPseudoInputsFlag){
            (void) fprintf(of, "%s ", Ntk_NodeReadName(node));
          }
        }
      }
      (void) fprintf(of, "; ");
    }
    
    if (printStatesFlag) {
      for (i = sim->currentStateHead; i < sim->internalPartitionHead; i++) {
        node = array_fetch(Ntk_Node_t *, sim->nodesArray, i);
        (void) fprintf(of, "%s ", Ntk_NodeReadName(node));
      }
      (void) fprintf(of, "; ");      
    }
    if (printOutputsFlag){
      for (i = sim->outputHead; i < numNodes; i++) {
        node = array_fetch(Ntk_Node_t *, sim->nodesArray, i);
        (void) fprintf(of, "%s ", Ntk_NodeReadName(node));
      }
      (void) fprintf(of, "\n\n");
    }
  }
  
  for (i = 0; i < array_n(sim->vectorArray); i++) {
    vector = array_fetch(array_t *, sim->vectorArray, i);
    if ((printInputsFlag) || (printPseudoInputsFlag)){
      for (j = 0; j < sim->currentStateHead; j++) {
        strSize = array_fetch(int, formatArray, j);
        node = array_fetch(Ntk_Node_t *, sim->nodesArray, j);
        if (Ntk_NodeTestIsPrimaryInput(node)){
          if(printInputsFlag){
            PrintValue(sim->nodesArray, vector, j, strSize, of);
          }
        }
        else {
          if (printPseudoInputsFlag){
            PrintValue(sim->nodesArray, vector, j, strSize, of);
          }
        }
      }
    }
    if (printStatesFlag){
      (void) fprintf(of,"; ");
      for (j = sim->currentStateHead; j < sim->internalPartitionHead; j++){
        strSize = array_fetch(int, formatArray, j);
        node = array_fetch(Ntk_Node_t *, sim->nodesArray, j);
        PrintValue(sim->nodesArray, vector, j, strSize, of);
      }
    }
    if (printOutputsFlag){
      (void) fprintf(of,"; ");
      for (j = sim->outputHead; j < numNodes; j++){
        strSize = array_fetch(int, formatArray, j);
        node = array_fetch(Ntk_Node_t *, sim->nodesArray, j);
        PrintValue(sim->nodesArray, vector, j, strSize, of);
      }
    }
    (void) fprintf(of, "\n");
  }
  if (printStatesFlag){
    /*
     * Need to print the final state on a separate line.
     */
    (void) fprintf(of,"# Final State : ");
    for (j = sim->currentStateHead; j < sim->internalPartitionHead; j++){
      strSize = array_fetch(int, formatArray, j);
      node = array_fetch(Ntk_Node_t *, sim->nodesArray, j);
      PrintValue(sim->nodesArray, vector, j, strSize, of);
    }
    (void) fprintf(of, "\n");
  }
  array_free(formatArray);
}



/**Function********************************************************************

  Synopsis [Parses the header of the simulation vectors file containing
  declarations, and builds a SimSimStruct.]

  Description [Parses the header of the simulation vectors file containing
  declarations, and builds a SimSimStruct. nodeToMvfTable providing MDDs of
  primary outputs and next-state functions is also built. verbose is here for
  initialization of sim structure. The header of a simulation-vectors file
  contains .inputs, .latches, .outputs, and .initial fields. If a variable is
  found for which there doesn't exist a corresponding node in the network, or
  a value is found that does not belong to the domain of its specific
  variable, then an error message is written in error_string, the allocated
  memory is freed, and the function returns NULL. The simulation file must
  contain each category of declaration in a line(Two ".inputs" is not allowed
  in the same file). initial-state declaration must be written after the
  latches declaration. The function returns the initialized sim structure.]

  SideEffects []

******************************************************************************/
Sim_Sim_t *
Sim_FileParseDeclaration(
  Ntk_Network_t * network,
  FILE          * fp,
  char          * inputFile,
  boolean         verbose)
{
  int            i;
  Ntk_Node_t    *node;
  char           buffer[MAX_LINE_LENGTH];
  char          *buffer2;
  int            currentStateHead;
  int            internalPartitionHead;
  int            nextStateHead;
  int            outputHead;
  st_table      *nodeToMvfTable;
  array_t       *nodesArray;
  int            lineNumber              = 0;
  array_t       *inputsArray             = NIL(array_t);
  array_t       *latchesArray            = NIL(array_t);
  array_t       *internalPartitionArray  = NIL(array_t);
  array_t       *outputsArray            = NIL(array_t);
  array_t       *initState               = NIL(array_t);
  Sim_Sim_t     *sim                     = NIL(Sim_Sim_t);
  graph_t       *partition;
  vertex_t      *vertex;
  array_t       *dfsarray;

  internalPartitionArray = array_alloc(Ntk_Node_t *, 0);

  /* Add internal partition nodes */
  partition = Part_NetworkReadPartition(network);
  dfsarray = g_dfs(partition);
  for(i=0; i< array_n(dfsarray); i++){
    vertex = array_fetch(vertex_t *, dfsarray, i);
    node = Ntk_NetworkFindNodeByName(network, Part_VertexReadName(vertex));
    if(!(Ntk_NodeTestIsCombInput(node) || Ntk_NodeTestIsCombOutput(node))){
      array_insert_last(Ntk_Node_t *, internalPartitionArray, node);
    }
  }
  array_free(dfsarray);

  while (fgets(buffer, MAX_LINE_LENGTH -1, fp) != NULL) {
    int position = 0;
    lineNumber++;

    /* Every line must end by '\n' */
    if (buffer[strlen(buffer) -1] != '\n') {
      SimAppendErrorMsg("Simulate: Line ",
                       SimInteger2ASCII(lineNumber), "istoolong!\n");
      FreeArrays(inputsArray, latchesArray, outputsArray, internalPartitionArray);
      return(sim);
    }
    
  
    /* Eliminate spaces */
    BufferSkipWhiteSpace(buffer, &position);
    /* buffer2 will contain buffer without space in the begining */
    buffer2 = buffer + position;
    /* Avoid comment and empty lines */
    if (buffer[position] != '#' && buffer[position] != '\n') {
      if (!strncmp(buffer2, ".inputs", 7)) {
        inputsArray = BufferBuildInputsNodeArray(buffer2 + 7, network);
        if (inputsArray == NIL(array_t)) {
          SimAppendErrorMsg("Simulate: Error line ",
                           SimInteger2ASCII(lineNumber), ".\n");
          FreeArrays(inputsArray, latchesArray, outputsArray, internalPartitionArray);
          return(sim);
        }
      }
      else if (!strncmp(buffer2, ".latches", 8)) {
        latchesArray = BufferBuildLatchesNodeArray(buffer2 + 8, network);
        if (latchesArray == NIL(array_t)) {
          SimAppendErrorMsg("Simulate: Error line ",
                           SimInteger2ASCII(lineNumber), ".\n");
          FreeArrays(inputsArray, latchesArray, outputsArray, internalPartitionArray);
          return(sim);
        }
      }
      else if (!strncmp(buffer2, ".outputs", 8)) {
        outputsArray = BufferBuildOutputsNodeArray(buffer2 + 8, network);
        if (outputsArray == NIL(array_t)) {
          SimAppendErrorMsg("Simulate: Error line ", SimInteger2ASCII(lineNumber),
                           ".\n");
          FreeArrays(inputsArray, latchesArray, outputsArray, internalPartitionArray);
          return(sim);
        }
      }
      else if (!strncmp(buffer2, ".initial", 8)) {
        /* Error if latches are not  already read before initial-state */
        if (latchesArray == NIL(array_t)) {
          error_append("Simulate: Latches must be declared before initial state declaration.\n");
          FreeArrays(inputsArray, latchesArray, outputsArray, internalPartitionArray);
          return(sim);
        }
        initState = BufferBuildValuesArray(buffer2 + 8, latchesArray);
        if (initState == NIL(array_t)) {
          SimAppendErrorMsg("Simulate: Error line ",
                           SimInteger2ASCII(lineNumber), ".\n");
          FreeArrays(inputsArray, latchesArray, outputsArray, internalPartitionArray);
          return(sim);
        }
      }
      else if (!strncmp(buffer2, ".start_vectors", 14)) {
        /* Verification of the declarations */
        if (inputsArray == NIL(array_t)) {
          error_append("Simulate: Input file is missing inputs declaration.\n");
          FreeArrays(inputsArray, latchesArray, outputsArray, internalPartitionArray);
          return(sim);
        }
          
        currentStateHead = array_n(inputsArray);
          
        nodesArray = array_dup(inputsArray);
        array_free(inputsArray);
        inputsArray = NIL(array_t);
        if(latchesArray == NIL(array_t)) {
          /* Verify if actually there is no latch in the network */
          if (Ntk_NetworkReadNumLatches(network) > 0) {
            error_append("Simulate: Input file is missing latches declaration.\n");
            FreeArrays(inputsArray, latchesArray, outputsArray, internalPartitionArray);
            return(0);
          }
          else {
            internalPartitionHead = currentStateHead;
            nextStateHead = internalPartitionHead + array_n(internalPartitionArray);
            outputHead = nextStateHead;
          }
        }
        else {
          internalPartitionHead = currentStateHead + array_n(latchesArray);
          nextStateHead = internalPartitionHead + array_n(internalPartitionArray);
          outputHead = nextStateHead + array_n(latchesArray);
          /* Add current states node */
          array_append(nodesArray, latchesArray);
          array_append(nodesArray, internalPartitionArray);
          array_free(internalPartitionArray);
          /* Add next state node as data-input of current-state node */
          for(i = 0; i < array_n(latchesArray); i++) {
            node = array_fetch(Ntk_Node_t *, latchesArray, i);
            node = Ntk_LatchReadDataInput(node);
            array_insert_last(Ntk_Node_t *, nodesArray, node);
          }
          array_free(latchesArray);
        }
        if (outputsArray != NIL(array_t)) {
          array_append(nodesArray, outputsArray);
          array_free(outputsArray);
        }
        /* Building nodeToMvfTable */
        nodeToMvfTable = Sim_NetworkBuildNodeToMvfTable(network, nodesArray,
                                                       internalPartitionHead,
                                                       nextStateHead);
        sim = Sim_SimCreate(network, nodeToMvfTable, inputFile, lineNumber,
                            nodesArray, currentStateHead, internalPartitionHead, 
                            nextStateHead, outputHead, initState, NULL, verbose);

        return(sim); /* Normal end */
      }
      
      /* Unknown string in the declaration part */
      else {
        SimAppendErrorMsg("Simulate: Syntax error in the declaration line: ",
                         SimInteger2ASCII(lineNumber),
                         " or missing .start_vectors statement.\n") ;
        FreeArrays(inputsArray, latchesArray, outputsArray, internalPartitionArray);
        return(sim);
      }
    }
  }
  array_free(internalPartitionArray);
  return(sim);  
}

/**Function********************************************************************

  Synopsis    [Parses the vectors of a simulation vectors file.]

  Description [Parses the vectors of a simulation vectors file. This function
  should be called after Sim_FileParseDeclaration. Reads lines from first line
  after ".start_vectors" statement. Fills the vectorArray field of sim. If
  this field is already set, it will be lost. Only "num" vectors are read(even
  if the number of vectors in the file is greater than this number). If num is
  0, then all vectors in the file are read.  If value is found that does not
  belong to the domain of its specific variable, then an error message is
  written in error_string, and the function returns 0. The function returns 1
  if it normally ends and no EOF is detected. It returns 2 otherwise(normal
  end and EOF).]

  SideEffects []

  SeeAlso     [Sim_FileParseDeclaration, Sim_SimReset]

******************************************************************************/
int
Sim_FileParseVectors(
  FILE      * fp,
  Sim_Sim_t  * sim,
  int         num)
{
  char           buffer[MAX_LINE_LENGTH];
  char          *buffer2;
  array_t       *vectorArray;
  int            numberVector            = 0;
  array_t       *inputsArray             = SimObtainInputsArray(sim);

  sim->vectorArray = array_alloc(array_t *, 0);
  
  while (fgets(buffer, MAX_LINE_LENGTH -1, fp) != NULL) {
    int position = 0;
    (sim->lineNumber)++;

    /* Every line must end by '\n' */
    if (buffer[strlen(buffer) -1] != '\n') {
      SimAppendErrorMsg("Simulate: Line ", SimInteger2ASCII(sim->lineNumber),
                       " is too long!\n");
      array_free(inputsArray);
      return(0);
    }
    
    /* Eliminate spaces */
    BufferSkipWhiteSpace(buffer, &position);
    /* buffer2 will contain buffer without space in the begining */
    buffer2 = buffer + position;
    /* Avoid comment and empty lines */
    if (buffer[position] != '#' && buffer[position] != '\n') {
      /* Read only "num" vectors */
      if (numberVector >= num && num != 0) {
        array_free(inputsArray);
        return(1); /* Normal end before EOF */
      }
      vectorArray = BufferBuildValuesArray(buffer2, inputsArray);
      if (vectorArray == NIL(array_t)) {
        SimAppendErrorMsg("Simulate: Error line ",
                         SimInteger2ASCII(sim->lineNumber), ".\n");
        array_free(inputsArray);
        return(0);
      }
      numberVector++;
      SimAddVector(sim, vectorArray);
    }
  }
  array_free(inputsArray);
  return(2); /* End of file */
}

/*---------------------------------------------------------------------------*/
/* Definition of internal functions                                          */
/*---------------------------------------------------------------------------*/

/*---------------------------------------------------------------------------*/
/* Definition of static functions                                            */
/*---------------------------------------------------------------------------*/
/**Function********************************************************************

  Synopsis    [Returns a new array containing the input nodes.]

  Description [Returns a new array containing the input nodes. If there is no
  inputs node in sim structure, then an empty array is returned.]
  
  SideEffects []

******************************************************************************/
static array_t *
SimObtainInputsArray(
  Sim_Sim_t * sim)
{
  int          i;
  Ntk_Node_t * node;
  array_t    * inputsArray = array_alloc(Ntk_Node_t *, 0);

  for (i = 0; i < sim->currentStateHead; i++) {
    node = array_fetch(Ntk_Node_t *, sim->nodesArray, i);
    array_insert_last(Ntk_Node_t *, inputsArray, node);
  }
  return(inputsArray);
}

/**Function********************************************************************

  Synopsis    [Frees arrays.]

  Description [Frees array. Verifies if array is non NULL.]
  
  SideEffects []

******************************************************************************/
static void
FreeArrays(
  array_t *array1,
  array_t *array2,
  array_t *array3,
  array_t *array4)
{
  if (array1 != NIL(array_t)) {
    array_free(array1);
  }
  if (array2 != NIL(array_t)) {
    array_free(array2);
  }
  if (array3 != NIL(array_t)) {
    array_free(array3);
  }
  if (array4 != NIL(array_t)) {
    array_free(array4);
  }
}
  

/**Function********************************************************************

  Synopsis    [Builds an array of nodes corresponding to the name of inputs
  read in the buffer.]

  Description [Builds an array of nodes corresponding to the name of inputs
  read in the buffer. If the name does not correspond to any input node in the
  network, or the number of values is not correct, then an error message is
  written in error_string, and NULL is returned.]
  
  SideEffects []

******************************************************************************/
static array_t *
BufferBuildInputsNodeArray(
  char * buffer,
  Ntk_Network_t * network)
{
  char       *str;
  Ntk_Node_t *node;
  int         position = 0;
  array_t    *array    = array_alloc(Ntk_Node_t *, 0);
    
  while((str = BufferObtainStringAtPosition(buffer, &position)) != NULL) {
    node = Ntk_NetworkFindNodeByActualName(network, str);
    if (node == NIL(Ntk_Node_t) || !Ntk_NodeTestIsInput(node)) {
      SimAppendErrorMsg("Simulate: ", str, " is not a valid input name.\n");
      array_free(array);
      FREE(str);
      return(NIL(array_t));
    }
    FREE(str);
    array_insert_last(Ntk_Node_t *, array, node);
  }
  /* Verification of number of values */
  if (array_n(array) != Ntk_NetworkReadNumInputs(network)) {
    error_append("Simulate: All inputs and pseudo-inputs must be specified.\n");
    array_free(array);
    return(NIL(array_t));
  }
  return(array);
}


/**Function********************************************************************

  Synopsis    [Builds an array of nodes corresponding to the name of latches
  read in the buffer.]

  Description [Builds an array of nodes corresponding to the name of latches
  read in the buffer. If the name does not correspond to any latch node in the
  network, or the number of values is not correct, then an error message is
  written in error_string, and NULL is returned.]
  
  SideEffects []

******************************************************************************/
static array_t *
BufferBuildLatchesNodeArray(
  char * buffer,
  Ntk_Network_t * network)
{
  char       *str;
  Ntk_Node_t *node;
  int         position = 0;
  array_t    *array    = array_alloc(Ntk_Node_t *, 0);
    
  while ((str = BufferObtainStringAtPosition(buffer, &position)) != NULL) {
    node = Ntk_NetworkFindNodeByActualName(network, str);
    if (node == NIL(Ntk_Node_t) || !Ntk_NodeTestIsLatch(node)) {
      SimAppendErrorMsg("Simulate: ", str, " is not a valid latch name\n");
      array_free(array);
      FREE(str);
      return(NIL(array_t));
    }
    FREE(str);
    array_insert_last(Ntk_Node_t *, array, node);
  }
  /* Verification of number of items */
  if (array_n(array) != Ntk_NetworkReadNumLatches(network)) {
    error_append("Simulate: All latches must be specified.\n");
    array_free(array);
    return(NIL(array_t));
  }
  return(array);
}

/**Function********************************************************************

  Synopsis    [Builds an array of nodes corresponding to the name of outputs
  read in the buffer.]

  Description [Builds an array of nodes corresponding to the name of outputs
  read in the buffer. If the name does not correspond to any output node in the
  network, then an error message is written in error_string, and NULL is
  returned. The number of outputs may be incomplete.]
  
  SideEffects []

******************************************************************************/
static array_t *
BufferBuildOutputsNodeArray(
  char * buffer,
  Ntk_Network_t * network)
{
  char       *str;
  Ntk_Node_t *node;
  int         position = 0;
  array_t    *array    = array_alloc(Ntk_Node_t *, 0);
    
  while((str = BufferObtainStringAtPosition(buffer, &position)) != NULL) {
    node = Ntk_NetworkFindNodeByActualName(network, str);
    if (node == NIL(Ntk_Node_t) || !Ntk_NodeTestIsPrimaryOutput(node)) {
      SimAppendErrorMsg("Simulate: ", str, " is not a valid output name\n");
      FREE(str);
      array_free(array);
      return(NIL(array_t));
    }
    FREE(str);
    array_insert_last(Ntk_Node_t *, array, node);
  }
  return(array);
}

/**Function********************************************************************

  Synopsis    [Builds an array of integers representing the code of strings
  contained in the buffer.]

  Description [Builds an array of integers representing the code of strings
  contained in the buffer. The code is 1 or 0, if the value is equal "1" or
  "0" and the variable is a binary variable. For a symbolic variable it is
  equal to the index of the value of the variable. The code is equal to the
  value of a variable if the variable has an enumerative type. If a wrong
  value is detected, then an error message is written in error_string and NULL
  is returned. This function verifies also if the number of values is equal to
  the number of nodes in the nodesArray. If it is not, it returns NULL.]
  
  SideEffects []

******************************************************************************/
static array_t *
BufferBuildValuesArray(
  char * buffer,
  array_t * nodesArray)
{
  char       *str;
  Ntk_Node_t *node;
  int         index;
  int         i         = 0;
  int         arraySize = array_n(nodesArray);
  int         position  = 0;
  array_t    *array     = array_alloc(int, 0);
    
  while((str = BufferObtainStringAtPosition(buffer, &position)) != NULL) {
    if (i >= arraySize) {
      SimAppendErrorMsg("Simulate: Too many values(", str, " invalid value).\n");
      array_free(array);
      FREE(str);
      return(NIL(array_t));
    }  
    node = array_fetch(Ntk_Node_t *, nodesArray, i);
    i++;
    index = SimNodeReadValueCode(node, str);
    if (index == -1) {
      SimAppendErrorMsg("Simulate: ", str, ": invalid value.\n");
      array_free(array);
      FREE(str);
      return(NIL(array_t));
    }

    FREE(str);
    array_insert_last(int, array, index);
  }
  
  /* Verification of number of items */
  if (array_n(array) != array_n(nodesArray)) {
    error_append("Simulate: incomplete number of values.\n");
    array_free(array);
    return(NIL(array_t));
  }
  return(array);
}


/**Function********************************************************************

  Synopsis    [Add a vector to the array of vectors of a sim.]

  Description [Add a vector to the array of vectors of a sim. It is an error
  to call this function with a NULL sim or a sim that does not have a vectors
  array.]
  
  SideEffects []

******************************************************************************/
static void
SimAddVector(
  Sim_Sim_t * sim,
  array_t * vector)
{
  array_insert_last(array_t *, sim->vectorArray, vector);
}

/**Function********************************************************************

  Synopsis    [skip over white space in a string.]

  Description [skip over white space in a string. set position to the first
  character different from ' ' and '\t'.]
  
  SideEffects []

******************************************************************************/
static void
BufferSkipWhiteSpace(
  char * buffer,
  int * position)
{
  for (; buffer[*position] == ' ' || buffer[*position] == '\t'; (*position)++);
}

/**Function********************************************************************

  Synopsis    [Returns a string read in a buffer at the given position.]

  Description [Returns a string read in a buffer at the given position. The
  end of string is detected by ' ', '\t', ';' or '\n'. Eliminates the Space in
  the begining of the buffer. Returns NULL if an empty string has been found
  before ';' or '\n'.]
  
  SideEffects []

******************************************************************************/
static char *
BufferObtainStringAtPosition(
  char * buffer,
  int * position)
{
  char *str;
  int   strPosition;
  int   len;
  
  /* Traverse Space */
  BufferSkipWhiteSpace(buffer, position);

  strPosition = *position;
  for (;buffer[*position] != ' ' && buffer[*position] != '\t' &&
            buffer[*position] != ';'  && buffer[*position] != '\n'; (*position)++);

  if (strPosition == *position) {
    return(NIL(char));
  }
  len = *position - strPosition + 1;
  str = ALLOC(char, len);
  strncpy(str, buffer + strPosition, len - 1);
  str[len-1] = '\0';
  return(str);
}

/**Function********************************************************************

  Synopsis    [Prints the value of a particular variable for a given
  simulation vector.]

  Description [Prints the value of a particular variable for a given
  simulation vector. The variable is obtained from the node at the
  vectorIndex position of the nodesArray. The value is obtained from
  the vectorIndex position of the vector. strSize is used for
  formatting. If the number of elements in the vector is less than the
  vectorIndex, a * is printed instead.]

  SideEffects []

******************************************************************************/
static void
PrintValue(array_t *nodesArray, array_t *vector, int vectorIndex,
           int strSize, FILE *file)
{
  int index;
  Var_Variable_t *var;
  char *str;
  Ntk_Node_t *node;
  
  if (array_n(vector) > vectorIndex) {
    node = array_fetch(Ntk_Node_t *, nodesArray, vectorIndex);
    var = Ntk_NodeReadVariable(node);
    index = array_fetch(int, vector, vectorIndex);
    if (Var_VariableTestIsSymbolic(var)) {
      SimStringPrint(file, Var_VariableReadSymbolicValueFromIndex(var, index),
                     strSize);
    }
    else { /* Binary or enumerative type */
      str = SimInteger2ASCII(index);
      SimStringPrint(file, str, strSize);
      FREE(str);
    }
  }
  else {
    error_append("Warning: Value is missing in vector.\n");
    SimStringPrint(file, "*", strSize);
  }
}