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/**CFile****************************************************************
FileName [dchChoice.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [Choice computation for tech-mapping.]
Synopsis [Contrustion of choices.]
Author [Alan Mishchenko]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - June 29, 2008.]
Revision [$Id: dchChoice.c,v 1.00 2008/07/29 00:00:00 alanmi Exp $]
***********************************************************************/
#include "dchInt.h"
ABC_NAMESPACE_IMPL_START
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Counts the number of representatives.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Dch_DeriveChoiceCountReprs( Aig_Man_t * pAig )
{
Aig_Obj_t * pObj, * pRepr;
int i, nReprs = 0;
Aig_ManForEachObj( pAig, pObj, i )
{
pRepr = Aig_ObjRepr( pAig, pObj );
if ( pRepr == NULL )
continue;
assert( pRepr->Id < pObj->Id );
nReprs++;
}
return nReprs;
}
/**Function*************************************************************
Synopsis [Counts the number of equivalences.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Dch_DeriveChoiceCountEquivs( Aig_Man_t * pAig )
{
Aig_Obj_t * pObj, * pTemp, * pPrev;
int i, nEquivs = 0, Counter = 0;
Aig_ManForEachObj( pAig, pObj, i )
{
if ( !Aig_ObjIsChoice(pAig, pObj) )
continue;
for ( pPrev = pObj, pTemp = Aig_ObjEquiv(pAig, pObj); pTemp;
pPrev = pTemp, pTemp = Aig_ObjEquiv(pAig, pTemp) )
{
if ( pTemp->nRefs > 0 )
{
// remove referenced node from equivalence class
assert( pAig->pEquivs[pPrev->Id] == pTemp );
pAig->pEquivs[pPrev->Id] = pAig->pEquivs[pTemp->Id];
pAig->pEquivs[pTemp->Id] = NULL;
// how about the need to continue iterating over the list?
// pPrev = pTemp ???
Counter++;
}
nEquivs++;
}
}
// printf( "Removed %d classes.\n", Counter );
if ( Counter )
Dch_DeriveChoiceCountEquivs( pAig );
// if ( Counter )
// printf( "Removed %d equiv nodes because of non-zero ref counter.\n", Counter );
return nEquivs;
}
/**Function*************************************************************
Synopsis [Returns 1 if the choice node of pRepr is in the TFI of pObj.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Dch_ObjCheckTfi_rec( Aig_Man_t * p, Aig_Obj_t * pObj )
{
// check the trivial cases
if ( pObj == NULL )
return 0;
if ( Aig_ObjIsPi(pObj) )
return 0;
if ( pObj->fMarkA )
return 1;
// skip the visited node
if ( Aig_ObjIsTravIdCurrent( p, pObj ) )
return 0;
Aig_ObjSetTravIdCurrent( p, pObj );
// check the children
if ( Dch_ObjCheckTfi_rec( p, Aig_ObjFanin0(pObj) ) )
return 1;
if ( Dch_ObjCheckTfi_rec( p, Aig_ObjFanin1(pObj) ) )
return 1;
// check equivalent nodes
return Dch_ObjCheckTfi_rec( p, Aig_ObjEquiv(p, pObj) );
}
/**Function*************************************************************
Synopsis [Returns 1 if the choice node of pRepr is in the TFI of pObj.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Dch_ObjCheckTfi( Aig_Man_t * p, Aig_Obj_t * pObj, Aig_Obj_t * pRepr )
{
Aig_Obj_t * pTemp;
int RetValue;
assert( !Aig_IsComplement(pObj) );
assert( !Aig_IsComplement(pRepr) );
// mark nodes of the choice node
for ( pTemp = pRepr; pTemp; pTemp = Aig_ObjEquiv(p, pTemp) )
pTemp->fMarkA = 1;
// traverse the new node
Aig_ManIncrementTravId( p );
RetValue = Dch_ObjCheckTfi_rec( p, pObj );
// unmark nodes of the choice node
for ( pTemp = pRepr; pTemp; pTemp = Aig_ObjEquiv(p, pTemp) )
pTemp->fMarkA = 0;
return RetValue;
}
/**Function*************************************************************
Synopsis [Returns representatives of fanin in approapriate polarity.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline Aig_Obj_t * Aig_ObjGetRepr( Aig_Man_t * p, Aig_Obj_t * pObj )
{
Aig_Obj_t * pRepr;
if ( (pRepr = Aig_ObjRepr(p, Aig_Regular(pObj))) )
return Aig_NotCond( pRepr, Aig_Regular(pObj)->fPhase ^ pRepr->fPhase ^ Aig_IsComplement(pObj) );
return pObj;
}
static inline Aig_Obj_t * Aig_ObjChild0CopyRepr( Aig_Man_t * p, Aig_Obj_t * pObj ) { return Aig_ObjGetRepr( p, Aig_ObjChild0Copy(pObj) ); }
static inline Aig_Obj_t * Aig_ObjChild1CopyRepr( Aig_Man_t * p, Aig_Obj_t * pObj ) { return Aig_ObjGetRepr( p, Aig_ObjChild1Copy(pObj) ); }
/**Function*************************************************************
Synopsis [Derives the AIG with choices from representatives.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Dch_DeriveChoiceAigNode( Aig_Man_t * pAigNew, Aig_Man_t * pAigOld, Aig_Obj_t * pObj )
{
Aig_Obj_t * pRepr, * pObjNew, * pReprNew;
// get the new node
pObj->pData = Aig_And( pAigNew,
Aig_ObjChild0CopyRepr(pAigNew, pObj),
Aig_ObjChild1CopyRepr(pAigNew, pObj) );
pRepr = Aig_ObjRepr( pAigOld, pObj );
if ( pRepr == NULL )
return;
// get the corresponding new nodes
pObjNew = Aig_Regular((Aig_Obj_t *)pObj->pData);
pReprNew = Aig_Regular((Aig_Obj_t *)pRepr->pData);
if ( pObjNew == pReprNew )
return;
// skip the earlier nodes
if ( pReprNew->Id > pObjNew->Id )
return;
assert( pReprNew->Id < pObjNew->Id );
// set the representatives
Aig_ObjSetRepr( pAigNew, pObjNew, pReprNew );
// skip used nodes
if ( pObjNew->nRefs > 0 )
return;
assert( pObjNew->nRefs == 0 );
// update new nodes of the object
if ( !Aig_ObjIsNode(pRepr) )
return;
// skip choices with combinational loops
if ( Dch_ObjCheckTfi( pAigNew, pObjNew, pReprNew ) )
return;
// add choice
pAigNew->pEquivs[pObjNew->Id] = pAigNew->pEquivs[pReprNew->Id];
pAigNew->pEquivs[pReprNew->Id] = pObjNew;
}
/**Function*************************************************************
Synopsis [Derives the AIG with choices from representatives.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Aig_Man_t * Dch_DeriveChoiceAig_old( Aig_Man_t * pAig )
{
Aig_Man_t * pChoices, * pTemp;
Aig_Obj_t * pObj;
int i;
// start recording equivalences
pChoices = Aig_ManStart( Aig_ManObjNumMax(pAig) );
pChoices->pEquivs = ABC_CALLOC( Aig_Obj_t *, Aig_ManObjNumMax(pAig) );
pChoices->pReprs = ABC_CALLOC( Aig_Obj_t *, Aig_ManObjNumMax(pAig) );
// map constants and PIs
Aig_ManCleanData( pAig );
Aig_ManConst1(pAig)->pData = Aig_ManConst1(pChoices);
Aig_ManForEachPi( pAig, pObj, i )
pObj->pData = Aig_ObjCreatePi( pChoices );
// construct choices for the internal nodes
assert( pAig->pReprs != NULL );
Aig_ManForEachNode( pAig, pObj, i )
Dch_DeriveChoiceAigNode( pChoices, pAig, pObj );
Aig_ManForEachPo( pAig, pObj, i )
Aig_ObjCreatePo( pChoices, Aig_ObjChild0CopyRepr(pChoices, pObj) );
Dch_DeriveChoiceCountEquivs( pChoices );
// there is no need for cleanup
ABC_FREE( pChoices->pReprs );
pChoices = Aig_ManDupDfs( pTemp = pChoices );
Aig_ManStop( pTemp );
return pChoices;
}
/**Function*************************************************************
Synopsis [Checks for combinational loops in the AIG.]
Description [Returns 1 if combinational loop is detected.]
SideEffects []
SeeAlso []
***********************************************************************/
int Aig_ManCheckAcyclic_rec( Aig_Man_t * p, Aig_Obj_t * pNode, int fVerbose )
{
Aig_Obj_t * pFanin;
int fAcyclic;
if ( Aig_ObjIsPi(pNode) || Aig_ObjIsConst1(pNode) )
return 1;
assert( Aig_ObjIsNode(pNode) );
// make sure the node is not visited
assert( !Aig_ObjIsTravIdPrevious(p, pNode) );
// check if the node is part of the combinational loop
if ( Aig_ObjIsTravIdCurrent(p, pNode) )
{
if ( fVerbose )
Abc_Print( 1, "Network \"%s\" contains combinational loop!\n", p->pSpec? p->pSpec : NULL );
if ( fVerbose )
Abc_Print( 1, "Node \"%d\" is encountered twice on the following path to the COs:\n", Aig_ObjId(pNode) );
return 0;
}
// mark this node as a node on the current path
Aig_ObjSetTravIdCurrent( p, pNode );
// visit the transitive fanin
pFanin = Aig_ObjFanin0(pNode);
// check if the fanin is visited
if ( !Aig_ObjIsTravIdPrevious(p, pFanin) )
{
// traverse the fanin's cone searching for the loop
if ( !(fAcyclic = Aig_ManCheckAcyclic_rec(p, pFanin, fVerbose)) )
{
// return as soon as the loop is detected
if ( fVerbose )
Abc_Print( 1, " %d ->", Aig_ObjId(pFanin) );
return 0;
}
}
// visit the transitive fanin
pFanin = Aig_ObjFanin1(pNode);
// check if the fanin is visited
if ( !Aig_ObjIsTravIdPrevious(p, pFanin) )
{
// traverse the fanin's cone searching for the loop
if ( !(fAcyclic = Aig_ManCheckAcyclic_rec(p, pFanin, fVerbose)) )
{
// return as soon as the loop is detected
if ( fVerbose )
Abc_Print( 1, " %d ->", Aig_ObjId(pFanin) );
return 0;
}
}
// visit choices
if ( Aig_ObjRepr(p, pNode) == NULL && Aig_ObjEquiv(p, pNode) != NULL )
{
for ( pFanin = Aig_ObjEquiv(p, pNode); pFanin; pFanin = Aig_ObjEquiv(p, pFanin) )
{
// check if the fanin is visited
if ( Aig_ObjIsTravIdPrevious(p, pFanin) )
continue;
// traverse the fanin's cone searching for the loop
if ( (fAcyclic = Aig_ManCheckAcyclic_rec(p, pFanin, fVerbose)) )
continue;
// return as soon as the loop is detected
if ( fVerbose )
Abc_Print( 1, " %d", Aig_ObjId(pFanin) );
if ( fVerbose )
Abc_Print( 1, " (choice of %d) -> ", Aig_ObjId(pNode) );
return 0;
}
}
// mark this node as a visited node
Aig_ObjSetTravIdPrevious( p, pNode );
return 1;
}
/**Function*************************************************************
Synopsis [Checks for combinational loops in the AIG.]
Description [Returns 1 if there is no combinational loops.]
SideEffects []
SeeAlso []
***********************************************************************/
int Aig_ManCheckAcyclic( Aig_Man_t * p, int fVerbose )
{
Aig_Obj_t * pNode;
int fAcyclic;
int i;
// set the traversal ID for this DFS ordering
Aig_ManIncrementTravId( p );
Aig_ManIncrementTravId( p );
// pNode->TravId == pNet->nTravIds means "pNode is on the path"
// pNode->TravId == pNet->nTravIds - 1 means "pNode is visited but is not on the path"
// pNode->TravId < pNet->nTravIds - 1 means "pNode is not visited"
// traverse the network to detect cycles
fAcyclic = 1;
Aig_ManForEachPo( p, pNode, i )
{
pNode = Aig_ObjFanin0(pNode);
if ( Aig_ObjIsTravIdPrevious(p, pNode) )
continue;
// traverse the output logic cone
if ( (fAcyclic = Aig_ManCheckAcyclic_rec(p, pNode, fVerbose)) )
continue;
// stop as soon as the first loop is detected
if ( fVerbose )
Abc_Print( 1, " CO %d\n", i );
break;
}
return fAcyclic;
}
/**Function*************************************************************
Synopsis [Removes combinational loop.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Aig_ManFixLoopProblem( Aig_Man_t * p, int fVerbose )
{
Aig_Obj_t * pObj;
int i, Counter = 0, Counter2 = 0;
Aig_ManForEachObj( p, pObj, i )
{
if ( !Aig_ObjIsTravIdCurrent(p, pObj) )
continue;
Counter2++;
if ( Aig_ObjRepr(p, pObj) == NULL && Aig_ObjEquiv(p, pObj) != NULL )
{
Aig_ObjSetEquiv(p, pObj, NULL);
Counter++;
}
}
if ( fVerbose )
Abc_Print( 1, "Fixed %d choice nodes on the path with %d objects.\n", Counter, Counter2 );
}
/**Function*************************************************************
Synopsis [Derives the AIG with choices from representatives.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Aig_Man_t * Dch_DeriveChoiceAigInt( Aig_Man_t * pAig )
{
Aig_Man_t * pChoices;
Aig_Obj_t * pObj;
int i;
// start recording equivalences
pChoices = Aig_ManStart( Aig_ManObjNumMax(pAig) );
pChoices->pEquivs = ABC_CALLOC( Aig_Obj_t *, Aig_ManObjNumMax(pAig) );
pChoices->pReprs = ABC_CALLOC( Aig_Obj_t *, Aig_ManObjNumMax(pAig) );
// map constants and PIs
Aig_ManCleanData( pAig );
Aig_ManConst1(pAig)->pData = Aig_ManConst1(pChoices);
Aig_ManForEachPi( pAig, pObj, i )
pObj->pData = Aig_ObjCreatePi( pChoices );
// construct choices for the internal nodes
assert( pAig->pReprs != NULL );
Aig_ManForEachNode( pAig, pObj, i )
Dch_DeriveChoiceAigNode( pChoices, pAig, pObj );
Aig_ManForEachPo( pAig, pObj, i )
Aig_ObjCreatePo( pChoices, Aig_ObjChild0CopyRepr(pChoices, pObj) );
Dch_DeriveChoiceCountEquivs( pChoices );
Aig_ManSetRegNum( pChoices, Aig_ManRegNum(pAig) );
return pChoices;
}
/**Function*************************************************************
Synopsis [Derives the AIG with choices from representatives.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Aig_Man_t * Dch_DeriveChoiceAig( Aig_Man_t * pAig )
{
extern int Aig_ManCheckAcyclic( Aig_Man_t * pAig, int fVerbose );
Aig_Man_t * pChoices, * pTemp;
int fVerbose = 0;
pChoices = Dch_DeriveChoiceAigInt( pAig );
// pChoices = Dch_DeriveChoiceAigInt( pTemp = pChoices );
// Aig_ManStop( pTemp );
// there is no need for cleanup
ABC_FREE( pChoices->pReprs );
while ( !Aig_ManCheckAcyclic( pChoices, fVerbose ) )
{
if ( fVerbose )
Abc_Print( 1, "There is a loop!\n" );
Aig_ManFixLoopProblem( pChoices, fVerbose );
}
pChoices = Aig_ManDupDfs( pTemp = pChoices );
Aig_ManStop( pTemp );
return pChoices;
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
ABC_NAMESPACE_IMPL_END
|
