source: vis_dev/vis-2.3/src/ntmaig/ntmaig.c @ 23

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

  FileName    [ntmaig.c]

  PackageName [ntmaig]

  Synopsis    [Routines to build mAigs from a network.]

  Author      [Mohammad Awedh]

  Copyright [ This file was created at the University of Colorado at
  Boulder.  The University of Colorado at Boulder makes no warranty
  about the suitability of this software for any purpose.  It is
  presented on an AS IS basis.]

******************************************************************************/

#include "ntmaigInt.h"
#include "baig.h"

static char rcsid[] UNUSED = "$Id: ntmaig.c,v 1.15 2005/04/28 08:54:35 bli Exp $";

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

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

static MvfAig_Function_t * NodeBuildMvfAigRecursively(Ntk_Node_t * node, st_table * leaves, st_table * nodeToMvfTable, mAig_Manager_t *manager);
static MvfAig_Function_t * NodeBuildInputMvfAig(mAig_Manager_t *manager, Ntk_Node_t * node);
static MvfAig_Function_t * NodeBuildPseudoInputMvfAigNew(mAig_Manager_t *manager, Ntk_Node_t * node);
/*static MvfAig_Function_t * NodeBuildPseudoInputMvfAig(mAig_Manager_t *manager, Ntk_Node_t * node);*/
static MvfAig_Function_t * NodeBuildConstantMvfAig(Ntk_Node_t * node, int constantValue, mAig_Manager_t *manager);
static MvfAig_Function_t * NodeBuildInternalMvfAig(Ntk_Node_t * node, st_table * leaves, st_table * nodeToMvfAigTable, mAig_Manager_t *manager);
static MvfAig_Function_t * NodeReadMvfAig(Ntk_Node_t * node, st_table * nodeToMvfAigTable);
static void NodeSetMvfAig(Ntk_Node_t * node, st_table * nodeToMvfAigTable, MvfAig_Function_t * MvfAig);
static void RegionInitializeReferenceCounts(array_t *roots, st_table *leaves);
static void NodeDecrementRefCount(Ntk_Node_t *node, st_table *nodeToMvfTable);

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


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

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

  Synopsis    [Builds multi-valued functions for roots, in terms of leaves.]

  Description [Takes an array of root nodes and a table of leaf nodes, and
  builds the multi-valued functions (MvfAigs) for the roots in terms of the
  leaves. This function returns an array of MvfAig_Function_t*, in one-to-one
  correspondence with the roots array.  It is assumed that every path, from a
  root backwards to a combinational input, passes through a node in the leaves
  table, and that there are no combinational cycles within the region defined
  by the roots and leaves. Also, it is assumed that every node in the leaves
  table already has an mAig Id.<p>

  A leaf that is a primary input, latch, or combinational node, is treated as
  a "free" input (i.e. can assume any value in its domain). A leaf that is a
  pseudo input can assume only those values for which it was specified.<p>

  The leaves table maps nodes (Ntk_Node_t*) to integers.  If the value
  corresponding to a leaf is ntmaig_UNUSED, then the MvfAig for the leaf is built
  as described above.  However, the value can be specified as the index of
  some value in the domain of the variable of the leaf.  For example, if leaf
  node x can take values (RED, GREEN, BLUE), then the value 1 refers to GREEN.
  In this case, the MvfAig built for x is simply the constant MvfAig representing
  This feature can be used to evaluate the MvfAigs of the roots on a minterm, or 
  partial minterm, over the leaves.<p>

  nodeToMvfAigTable is a table mapping nodes to MvfAig_Function_t's (for nodes for
  which MvfAig_Function's have already been built); Call NodeBuildMvfAigRecursively
  on the roots. Free MvfAig's at internal nodes ASAP, so no excessive storage.]

  SideEffects []
******************************************************************************/
array_t *
ntmaig_NetworkBuildMvfAigs(
  Ntk_Network_t * network,
  array_t       * roots,
  st_table      * leaves)
{
  int               i;
  MvfAig_Function_t *MvfAig;
  st_table          *nodeToMvfAigTable;  /* mapes each node with its mvfAig */
  int                numRoots = array_n(roots);
  array_t           *result   = array_alloc(MvfAig_Function_t *, numRoots);
  mAig_Manager_t    *manager  = Ntk_NetworkReadMAigManager(network);
  MvfAig_Function_t *tmpMvf;

  
  /*
   * Before initializing the reference counts, verify that the leaves form a
   * support set for the roots.
   */
  if (!Ntk_NetworkTestLeavesCoverSupportOfRoots(network, roots, leaves)) {
    fail("Leaves do not cover support of roots");
  }
  /*
   * Each node in the region defined by the roots and leaves is assigned a
   * reference count equaling the number of fanouts within the region.  As a
   * special case, the roots are initialized to MAX_INT.
   */
  RegionInitializeReferenceCounts(roots, leaves);
  /*
   * For each root, compute its MvfAig and store a duplicate copy of it in the
   * result array. The nodeToMvfAigTable is used to keep track of intermediate
   * computations. Intermediate MvfAigs are freed as soon as possible by using
   * the reference count mechanism.
   */
  nodeToMvfAigTable = (st_table *) Ntk_NetworkReadApplInfo(network, MVFAIG_NETWORK_APPL_KEY);
  if (nodeToMvfAigTable == NIL(st_table)){
    nodeToMvfAigTable = st_init_table(st_ptrcmp, st_ptrhash);
    /* Register the MvfAig Table in the network*/
    Ntk_NetworkAddApplInfo(network, MVFAIG_NETWORK_APPL_KEY,
                         (Ntk_ApplInfoFreeFn) ntmAig_MvfAigTableFreeCallback,
                         (void *) nodeToMvfAigTable);
  }
  for (i = 0; i < numRoots; i++) {
    Ntk_Node_t        *root   = array_fetch(Ntk_Node_t *, roots, i);
    tmpMvf = NodeBuildMvfAigRecursively(root, leaves,
                                     nodeToMvfAigTable, manager);
    MvfAig = MvfAig_FunctionDuplicate(tmpMvf);
    array_insert(MvfAig_Function_t *, result, i, MvfAig);
  }

  return result;
}

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

  Synopsis    [Call-back function to free a MvfAig Table.]

  Description [This function will be stored in the network together with the
  pointer to the MvfAig Table. Whenever the network deletes the MvfAig 
  information, this function is called and it will free the table and
  the information attached to it.]

  SideEffects []

  SeeAlso     [Ntk_NetworkAddApplInfo]

******************************************************************************/
void
ntmAig_MvfAigTableFreeCallback(
   void *data)
{
  st_generator      *stGen;
  MvfAig_Function_t *MvfAig;
  Ntk_Node_t        *node;
  st_table          *nodeToMvfAigTable = (st_table*) data;

  st_foreach_item(nodeToMvfAigTable, stGen,  &node,  &MvfAig) {
    MvfAig_FunctionFree(MvfAig);
  }
  st_free_table(nodeToMvfAigTable);
} /* End of ntmAig_MvfAigTableFreeCallback */


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


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


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

  Synopsis    [Builds MvfAig for a node, recursively in terms of fanins.]

  Description [Recursively builds MvfAig_Functions_t's. Base cases - input nodes,
  latch nodes, constant nodes, pseudo inputs, and leaf nodes. Fail if a
  combinational input is reached that is not in leaves.  In the case that the
  node is combinational, and in the leaves, we treat it as an input.  When
  it's a pseudo input, we treat it as taking only values designated in table.]

  SideEffects []

  SeeAlso     [NodeBuildInputMvfAig,NodeBuildPseudoInputMvfAig,NodeBuildInternalMvfAig]
[Done]
******************************************************************************/
static MvfAig_Function_t *
NodeBuildMvfAigRecursively(
  Ntk_Node_t * node,
  st_table * leaves,
  st_table * nodeToMvfTable,
  mAig_Manager_t *manager)
{
  MvfAig_Function_t *MvfAig = NodeReadMvfAig(node, nodeToMvfTable);
  
  /* If the MvfAig for this node has already been computed, then just return it. */

  if (MvfAig != NIL(MvfAig_Function_t)) {
    return MvfAig;
  }
  if (Ntk_NodeTestIsConstant(node)) {
    /* Doesn't matter if constant is a leaf or not. */
    MvfAig = NodeBuildConstantMvfAig(node, ntmaig_UNUSED, manager);
  }
  else {
    int constValue;
  
    if (st_lookup_int(leaves,  node, &constValue)) { 
      if (constValue == ntmaig_UNUSED) {
        /* Node is a leaf. */
        if ((Ntk_NodeTestIsPrimaryInput(node)) ||
            (Ntk_NodeTestIsLatch(node)) ||
            (Ntk_NodeTestIsCombinational(node))) {
          /* Node can assume any value. */
          MvfAig = NodeBuildInputMvfAig(manager, node);
        }
        else if (Ntk_NodeTestIsPseudoInput(node)) {
          /* Node may assume only a subset of possible values. */
          MvfAig = NodeBuildPseudoInputMvfAigNew(manager, node);
        }
        else {
          fail("Encountered unknown type in MvfAig recursion\n");
        }
      }
      else {
        /* treat the leaf node as being a constant taking the value constValue */
        MvfAig = NodeBuildConstantMvfAig(node, constValue, manager);
      }
    }
    else {

      /* Node is not a leaf.  If it is a combinational input, then fail. */
      if (Ntk_NodeTestIsCombInput(node)) {
        fail("Encountered combinational input not in leaves table\n");
      }
      else {
        MvfAig = NodeBuildInternalMvfAig(node, leaves, nodeToMvfTable, manager);
      }
    }
  }
  NodeSetMvfAig(node, nodeToMvfTable, MvfAig);
  return MvfAig;

}


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

  Synopsis  [Builds MvfAig for a node that is treated as a free input.]

  SideEffects []
[Done]
******************************************************************************/
static MvfAig_Function_t *
NodeBuildInputMvfAig(
  mAig_Manager_t *manager,
  Ntk_Node_t * node)
{
  int mAigId = Ntk_NodeReadMAigId(node);

  assert(mAigId != NTK_UNASSIGNED_MAIG_ID);
  return MvfAig_FunctionCreateFromVariable(manager, mAigId);
}

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

  Synopsis    [Builds MvfAig for a node that is a pseudo input.]

  Description [Builds MvfAig for a node that is a pseudo input.  This node has
  a single output and no inputs. Its table has several row entries.  We build
  an MvfAig whose components correspond exactly to possible table outputs.]

  SideEffects []

 Comment [Although pseudo inputs, constants, and internal nodes all have
  tables, a single procedure cannot be used to build their MvfAig.  A pseudo
  input MvfAig is built in terms of its mddId, whereas a constant or internal is
  not.  A constant or pseudo input doesn't have any inputs, whereas an
  internal does.]
  
  SeeAlso     [Tbl_TableBuildMvfAigForNonDetConstant]
[Done]
******************************************************************************/
static MvfAig_Function_t *
NodeBuildPseudoInputMvfAigNew(
  mAig_Manager_t *manager,
  Ntk_Node_t * node)
{
  int lIndex=0, needProcess, i;
  mAigEdge_t  mAig, tmpAig;
  MvfAig_Function_t *MvfAig;
  int                columnIndex = Ntk_NodeReadOutputIndex(node);
  Tbl_Table_t       *table       = Ntk_NodeReadTable(node);
  int                mAigId      = Ntk_NodeReadMAigId(node);

  assert(mAigId != NTK_UNASSIGNED_MAIG_ID);
  MvfAig = Tbl_TableBuildNonDetConstantMvfAig(table, columnIndex,
mAigId,
                                              manager);
  needProcess = 0;
  tmpAig = mAig_Zero;
  for(i=0; i<MvfAig->num; i++) {
    mAig = array_fetch(mAigEdge_t, MvfAig, i);
    if(mAig == tmpAig) {
      needProcess = 1;
    }
    else {
      lIndex = i;
    }
  }
  if(needProcess) {
    for(i=0; i<lIndex; i++) {
      mAig   = array_fetch(mAigEdge_t, MvfAig, i);
      tmpAig = mAig_Or(manager, tmpAig, mAig);
    }
    array_insert(mAigEdge_t, MvfAig, lIndex, mAig_Not(tmpAig));
  }
  
  return MvfAig;
}

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

  Synopsis    [Builds MvfAig for a node that is a pseudo input.]

  Description [Builds MvfAig for a node that is a pseudo input.  This node has a
  single output and no inputs. Its table has several row entries.  We build an
  MvfAig whose components correspond exactly to possible table outputs.]

  SideEffects []

  Comment [Although pseudo inputs, constants, and internal nodes all have
  tables, a single procedure cannot be used to build their MvfAig.  A pseudo
  input MvfAig is built in terms of its mddId, whereas a constant or internal is
  not.  A constant or pseudo input doesn't have any inputs, whereas an
  internal does.]
  
  SeeAlso     [Tbl_TableBuildMvfAigForNonDetConstant]
[Done]
******************************************************************************/
/*static MvfAig_Function_t *
NodeBuildPseudoInputMvfAig(
  mAig_Manager_t *manager,
  Ntk_Node_t * node)
{
  MvfAig_Function_t *MvfAig;
  int                columnIndex = Ntk_NodeReadOutputIndex(node);
  Tbl_Table_t       *table       = Ntk_NodeReadTable(node);
  int                mAigId      = Ntk_NodeReadMAigId(node);

  assert(mAigId != NTK_UNASSIGNED_MAIG_ID);
  MvfAig = Tbl_TableBuildNonDetConstantMvfAig(table, columnIndex, mAigId, manager);
  return MvfAig;
}*/


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

  Synopsis [Builds MvfAig for a node with no inputs, and only one row in its
  table.]

  Description [Builds MvfAig for a constant.  If constantValue is ntmaig_UNUSED,
  then constantValue should be a legal index in the domain of the variable of
  node. In this case, regardless of the type of the node, an MvfAig is built
  where the component indexed by constantValue is one (i.e. the tautology) and
  all other components are zero.<p>

  If constantValue is not ntmaig_UNUSED, then node should be a constant,
  combinational node.  In this case, an MvfAig is built with a single component
  (indexed by the value of node) is one, and all other components are zero.]

  SideEffects []
[Done]
******************************************************************************/
static MvfAig_Function_t *
NodeBuildConstantMvfAig(
  Ntk_Node_t * node,
  int constantValue,
  mAig_Manager_t *manager)
{
  int             value        = 0; /* initialized to stop lint complaining */
  Var_Variable_t *variable     = Ntk_NodeReadVariable(node);
  int             numVarValues = Var_VariableReadNumValues(variable);
  MvfAig_Function_t *MvfAig    = MvfAig_FunctionAlloc(numVarValues);

  if (constantValue != ntmaig_UNUSED) {
    /* Use the given value. */
    assert((constantValue >= 0) && (constantValue < numVarValues));
    value = constantValue;
  }
  else {
    int          outputIndex = Ntk_NodeReadOutputIndex(node);
    Tbl_Table_t *table       = Ntk_NodeReadTable(node);

    assert(Ntk_NodeTestIsConstant(node));
    value = Tbl_TableReadConstValue(table, outputIndex);
    assert(value != -1);
  }
  
  MvfAig_FunctionAddMintermsToComponent(manager, MvfAig, value, bAig_One);
  return MvfAig;
}


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

  Synopsis [Builds MvfAig for an internal node in terms of its fanin's MvfAigs.]

  Description [Builds MvfAig for an internal node in terms of its fanin's
  MvfAigs. An internal node is a node that is in the transitive fanin of a root,
  but is not a leaf.]

  SideEffects []
[Done]
******************************************************************************/
static MvfAig_Function_t *
NodeBuildInternalMvfAig(
  Ntk_Node_t * node,
  st_table   * leaves,
  st_table   * nodeToMvfAigTable,
  mAig_Manager_t *manager)
{
  int               i;
  MvfAig_Function_t *resultMvfAig;
  Ntk_Node_t        *faninNode;
  array_t           *faninMvfAigs = array_alloc(MvfAig_Function_t *, Ntk_NodeReadNumFanins(node));
  int               outputIndex   = Ntk_NodeReadOutputIndex(node);
  Tbl_Table_t       *table        = Ntk_NodeReadTable(node);

  Ntk_NodeForEachFanin(node, i, faninNode) {
    MvfAig_Function_t *tmpMvfAig = NodeBuildMvfAigRecursively(faninNode, leaves,
                                                              nodeToMvfAigTable, manager);
    array_insert(MvfAig_Function_t *, faninMvfAigs, i, tmpMvfAig);
  }
  resultMvfAig = Tbl_TableBuildMvfAigFromFanins(table, outputIndex, faninMvfAigs, manager); 
  Ntk_NodeForEachFanin(node, i, faninNode) {
    NodeDecrementRefCount(faninNode, nodeToMvfAigTable);
  }
  /* Don't free the MvfAigs themselves, but just free the array. */
  array_free(faninMvfAigs);
  return resultMvfAig;
}


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

  Synopsis [Returns MvfAig corresponding to a node; returns NIL if node not in
  table.]

  SideEffects []
[Done]
******************************************************************************/
static MvfAig_Function_t *
NodeReadMvfAig(
  Ntk_Node_t * node,
  st_table   * nodeToMvfAigTable)
{
  MvfAig_Function_t *result = NIL(MvfAig_Function_t);
  st_lookup(nodeToMvfAigTable,  node,  &result);

  return result;
}


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

  Synopsis    [Inserts node and corresponding MvfAig into table.]

  SideEffects []
[Done]
******************************************************************************/
static void
NodeSetMvfAig(
  Ntk_Node_t * node,
  st_table   * nodeToMvfAigTable,
  MvfAig_Function_t * MvfAig)
{
  st_insert(nodeToMvfAigTable,  node,  MvfAig);
}

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

  Synopsis    [Initializes the reference counts in a region.]

  Description [Initializes the reference counts in the region defined by the
  roots and leaves.  This region includes the roots, and all nodes in the
  transitive fanin of the roots up to and including the leaves.  The reference
  count for a node in the region is set to be the number of fanouts of that
  node in the region (fanouts to leaf nodes and constant nodes are excluded).
  Root nodes are set to MAXINT, so that even after some decrements, their ref
  count won't fall to zero.]

  SideEffects [Uses the undef field of node.]

******************************************************************************/
static void
RegionInitializeReferenceCounts(
  array_t *roots, 
  st_table *leaves)
{
  int           i;
  Ntk_Node_t   *node;
  st_generator *stGen;
  st_table     *regionNodes = Ntk_RegionFindNodes(roots, leaves);

  st_foreach_item(regionNodes, stGen,  &node, NIL(char *)) {
    Ntk_Node_t *fanoutNode;
    long        refCount = 0;

    Ntk_NodeForEachFanout(node, i, fanoutNode) {
      if (st_is_member(regionNodes,  fanoutNode)
          && !st_is_member(leaves,  fanoutNode)
          && !Ntk_NodeTestIsConstant(fanoutNode)) {
        refCount++;
      }
    }
    Ntk_NodeSetUndef(node, (void *) refCount);
  }

  for(i = 0; i < array_n(roots); i++) {
    node = array_fetch(Ntk_Node_t *, roots, i);
    Ntk_NodeSetUndef(node, (char *) MAXINT);
  }

  st_free_table(regionNodes);
}

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

  Synopsis    [Decrements the ref count of a node.]

  Description [Decrements the ref count of a node.  If the ref count becomes
  zero, then remove node from nodeToMvfTable and free the MVF corresponding to
  node.]

  SideEffects []

******************************************************************************/
static void
NodeDecrementRefCount(
  Ntk_Node_t *node, 
  st_table *nodeToMvfTable)
{
  long              refCount = (long) Ntk_NodeReadUndef(node);

  assert(refCount != 0);

  refCount--;
  /*  
    Want to keep the entry of this node, so we may get the MvfAig of this node
    whenever we need it.  The pointer to the nodeToMvfTable is stored in the network
    information.
   */
  /*  
  if (refCount == 0) {
    st_delete(nodeToMvfTable, (char **) &node, (char **) &mvf);
    MvfAig_FunctionFree(mvf);
  }
  */
  Ntk_NodeSetUndef(node, (void *) refCount);
}