hopBalance.c File Reference

#include "hop.h"

Go to the source code of this file.

Functions
static ABC_NAMESPACE_IMPL_START Hop_Obj_t *	Hop_NodeBalance_rec (Hop_Man_t *pNew, Hop_Obj_t *pObj, Vec_Vec_t *vStore, int Level, int fUpdateLevel)
	DECLARATIONS ///. More...
static Vec_Ptr_t *	Hop_NodeBalanceCone (Hop_Obj_t *pObj, Vec_Vec_t *vStore, int Level)
static int	Hop_NodeBalanceFindLeft (Vec_Ptr_t *vSuper)
static void	Hop_NodeBalancePermute (Hop_Man_t *p, Vec_Ptr_t *vSuper, int LeftBound, int fExor)
static void	Hop_NodeBalancePushUniqueOrderByLevel (Vec_Ptr_t *vStore, Hop_Obj_t *pObj)
Hop_Man_t *	Hop_ManBalance (Hop_Man_t *p, int fUpdateLevel)
	FUNCTION DEFINITIONS ///. More...
int	Hop_NodeBalanceCone_rec (Hop_Obj_t *pRoot, Hop_Obj_t *pObj, Vec_Ptr_t *vSuper)
int	Hop_NodeCompareLevelsDecrease (Hop_Obj_t **pp1, Hop_Obj_t **pp2)
Hop_Obj_t *	Hop_NodeBalanceBuildSuper (Hop_Man_t *p, Vec_Ptr_t *vSuper, Hop_Type_t Type, int fUpdateLevel)

Function Documentation

Hop_Man_t* Hop_ManBalance	(	Hop_Man_t *	p,
		int	fUpdateLevel
	)

FUNCTION DEFINITIONS ///.

FUNCTION DECLARATIONS ///.

Function*************************************************************

Synopsis [Performs algebraic balancing of the AIG.]

Description []

SideEffects []

SeeAlso []

Definition at line 51 of file hopBalance.c.

{
    Hop_Man_t * pNew;
    Hop_Obj_t * pObj, * pObjNew;
    Vec_Vec_t * vStore;
    int i;
    // create the new manager 
    pNew = Hop_ManStart();
    pNew->fRefCount = 0;
    // map the PI nodes
    Hop_ManCleanData( p );
    Hop_ManConst1(p)->pData = Hop_ManConst1(pNew);
    Hop_ManForEachPi( p, pObj, i )
        pObj->pData = Hop_ObjCreatePi(pNew);
    // balance the AIG
    vStore = Vec_VecAlloc( 50 );
    Hop_ManForEachPo( p, pObj, i )
    {
        pObjNew = Hop_NodeBalance_rec( pNew, Hop_ObjFanin0(pObj), vStore, 0, fUpdateLevel );
        Hop_ObjCreatePo( pNew, Hop_NotCond( pObjNew, Hop_ObjFaninC0(pObj) ) );
    }
    Vec_VecFree( vStore );
    // remove dangling nodes
//    Hop_ManCreateRefs( pNew );
//    if ( i = Hop_ManCleanup( pNew ) )
//        printf( "Cleanup after balancing removed %d dangling nodes.\n", i );
    // check the resulting AIG
    if ( !Hop_ManCheck(pNew) )
        printf( "Hop_ManBalance(): The check has failed.\n" );
    return pNew;
}

Hop_Obj_t * Hop_NodeBalance_rec ( Hop_Man_t *  pNew, Hop_Obj_t *  pObjOld, Vec_Vec_t *  vStore, int  Level, int  fUpdateLevel  )

static

DECLARATIONS ///.

CFile****************************************************************

FileName [hopBalance.c]

SystemName [ABC: Logic synthesis and verification system.]

PackageName [Minimalistic And-Inverter Graph package.]

Synopsis [Algebraic AIG balancing.]

Author [Alan Mishchenko]

Affiliation [UC Berkeley]

Date [Ver. 1.0. Started - May 11, 2006.]

Revision [

Id:

hopBalance.c,v 1.00 2006/05/11 00:00:00 alanmi Exp

]

Function*************************************************************

Synopsis [Returns the new node constructed.]

Description []

SideEffects []

SeeAlso []

Definition at line 94 of file hopBalance.c.

{
    Hop_Obj_t * pObjNew;
    Vec_Ptr_t * vSuper;
    int i;
    assert( !Hop_IsComplement(pObjOld) );
    // return if the result is known
    if ( pObjOld->pData )
        return (Hop_Obj_t *)pObjOld->pData;
    assert( Hop_ObjIsNode(pObjOld) );
    // get the implication supergate
    vSuper = Hop_NodeBalanceCone( pObjOld, vStore, Level );
    // check if supergate contains two nodes in the opposite polarity
    if ( vSuper->nSize == 0 )
        return (Hop_Obj_t *)(pObjOld->pData = Hop_ManConst0(pNew));
    if ( Vec_PtrSize(vSuper) < 2 )
        printf( "BUG!\n" );
    // for each old node, derive the new well-balanced node
    for ( i = 0; i < Vec_PtrSize(vSuper); i++ )
    {
        pObjNew = Hop_NodeBalance_rec( pNew, Hop_Regular((Hop_Obj_t *)vSuper->pArray[i]), vStore, Level + 1, fUpdateLevel );
        vSuper->pArray[i] = Hop_NotCond( pObjNew, Hop_IsComplement((Hop_Obj_t *)vSuper->pArray[i]) );
    }
    // build the supergate
    pObjNew = Hop_NodeBalanceBuildSuper( pNew, vSuper, Hop_ObjType(pObjOld), fUpdateLevel );
    // make sure the balanced node is not assigned
//    assert( pObjOld->Level >= Hop_Regular(pObjNew)->Level );
    assert( pObjOld->pData == NULL );
    return (Hop_Obj_t *)(pObjOld->pData = pObjNew);
}

Hop_Obj_t* Hop_NodeBalanceBuildSuper	(	Hop_Man_t *	p,
		Vec_Ptr_t *	vSuper,
		Hop_Type_t	Type,
		int	fUpdateLevel
	)

Function*************************************************************

Synopsis [Builds implication supergate.]

Description []

SideEffects []

SeeAlso []

Definition at line 243 of file hopBalance.c.

{
    Hop_Obj_t * pObj1, * pObj2;
    int LeftBound;
    assert( vSuper->nSize > 1 );
    // sort the new nodes by level in the decreasing order
    Vec_PtrSort( vSuper, (int (*)(void))Hop_NodeCompareLevelsDecrease );
    // balance the nodes
    while ( vSuper->nSize > 1 )
    {
        // find the left bound on the node to be paired
        LeftBound = (!fUpdateLevel)? 0 : Hop_NodeBalanceFindLeft( vSuper );
        // find the node that can be shared (if no such node, randomize choice)
        Hop_NodeBalancePermute( p, vSuper, LeftBound, Type == AIG_EXOR );
        // pull out the last two nodes
        pObj1 = (Hop_Obj_t *)Vec_PtrPop(vSuper);
        pObj2 = (Hop_Obj_t *)Vec_PtrPop(vSuper);
        Hop_NodeBalancePushUniqueOrderByLevel( vSuper, Hop_Oper(p, pObj1, pObj2, Type) );
    }
    return (Hop_Obj_t *)Vec_PtrEntry(vSuper, 0);
}

Vec_Ptr_t * Hop_NodeBalanceCone ( Hop_Obj_t *  pObj, Vec_Vec_t *  vStore, int  Level  )

static

Function*************************************************************

Synopsis [Collects the nodes of the supergate.]

Description []

SideEffects []

SeeAlso []

Definition at line 182 of file hopBalance.c.

{
    Vec_Ptr_t * vNodes;
    int RetValue, i;
    assert( !Hop_IsComplement(pObj) );
    // extend the storage
    if ( Vec_VecSize( vStore ) <= Level )
        Vec_VecPush( vStore, Level, 0 );
    // get the temporary array of nodes
    vNodes = Vec_VecEntry( vStore, Level );
    Vec_PtrClear( vNodes );
    // collect the nodes in the implication supergate
    RetValue = Hop_NodeBalanceCone_rec( pObj, pObj, vNodes );
    assert( vNodes->nSize > 1 );
    // unmark the visited nodes
    Vec_PtrForEachEntry( Hop_Obj_t *, vNodes, pObj, i )
        Hop_Regular(pObj)->fMarkB = 0;
    // if we found the node and its complement in the same implication supergate, 
    // return empty set of nodes (meaning that we should use constant-0 node)
    if ( RetValue == -1 )
        vNodes->nSize = 0;
    return vNodes;
}

int Hop_NodeBalanceCone_rec	(	Hop_Obj_t *	pRoot,
		Hop_Obj_t *	pObj,
		Vec_Ptr_t *	vSuper
	)

Function*************************************************************

Synopsis [Collects the nodes of the supergate.]

Description []

SideEffects []

SeeAlso []

Definition at line 136 of file hopBalance.c.

{
    int RetValue1, RetValue2, i;
    // check if the node is visited
    if ( Hop_Regular(pObj)->fMarkB )
    {
        // check if the node occurs in the same polarity
        for ( i = 0; i < vSuper->nSize; i++ )
            if ( vSuper->pArray[i] == pObj )
                return 1;
        // check if the node is present in the opposite polarity
        for ( i = 0; i < vSuper->nSize; i++ )
            if ( vSuper->pArray[i] == Hop_Not(pObj) )
                return -1;
        assert( 0 );
        return 0;
    }
    // if the new node is complemented or a PI, another gate begins
    if ( pObj != pRoot && (Hop_IsComplement(pObj) || Hop_ObjType(pObj) != Hop_ObjType(pRoot) || Hop_ObjRefs(pObj) > 1 || Vec_PtrSize(vSuper) > 10000) )
    {
        Vec_PtrPush( vSuper, pObj );
        Hop_Regular(pObj)->fMarkB = 1;
        return 0;
    }
    assert( !Hop_IsComplement(pObj) );
    assert( Hop_ObjIsNode(pObj) );
    // go through the branches
    RetValue1 = Hop_NodeBalanceCone_rec( pRoot, Hop_ObjChild0(pObj), vSuper );
    RetValue2 = Hop_NodeBalanceCone_rec( pRoot, Hop_ObjChild1(pObj), vSuper );
    if ( RetValue1 == -1 || RetValue2 == -1 )
        return -1;
    // return 1 if at least one branch has a duplicate
    return RetValue1 || RetValue2;
}

int Hop_NodeBalanceFindLeft ( Vec_Ptr_t *  vSuper )

static

Function*************************************************************

Synopsis [Finds the left bound on the next candidate to be paired.]

Description [The nodes in the array are in the decreasing order of levels. The last node in the array has the smallest level. By default it would be paired with the next node on the left. However, it may be possible to pair it with some other node on the left, in such a way that the new node is shared. This procedure finds the index of the left-most node, which can be paired with the last node.]

SideEffects []

SeeAlso []

Definition at line 280 of file hopBalance.c.

{
    Hop_Obj_t * pObjRight, * pObjLeft;
    int Current;
    // if two or less nodes, pair with the first
    if ( Vec_PtrSize(vSuper) < 3 )
        return 0;
    // set the pointer to the one before the last
    Current = Vec_PtrSize(vSuper) - 2;
    pObjRight = (Hop_Obj_t *)Vec_PtrEntry( vSuper, Current );
    // go through the nodes to the left of this one
    for ( Current--; Current >= 0; Current-- )
    {
        // get the next node on the left
        pObjLeft = (Hop_Obj_t *)Vec_PtrEntry( vSuper, Current );
        // if the level of this node is different, quit the loop
        if ( Hop_ObjLevel(Hop_Regular(pObjLeft)) != Hop_ObjLevel(Hop_Regular(pObjRight)) )
            break;
    }
    Current++;    
    // get the node, for which the equality holds
    pObjLeft = (Hop_Obj_t *)Vec_PtrEntry( vSuper, Current );
    assert( Hop_ObjLevel(Hop_Regular(pObjLeft)) == Hop_ObjLevel(Hop_Regular(pObjRight)) );
    return Current;
}

void Hop_NodeBalancePermute ( Hop_Man_t *  p, Vec_Ptr_t *  vSuper, int  LeftBound, int  fExor  )

static

Function*************************************************************

Synopsis [Moves closer to the end the node that is best for sharing.]

Description [If there is no node with sharing, randomly chooses one of the legal nodes.]

SideEffects []

SeeAlso []

Definition at line 318 of file hopBalance.c.

{
    Hop_Obj_t * pObj1, * pObj2, * pObj3, * pGhost;
    int RightBound, i;
    // get the right bound
    RightBound = Vec_PtrSize(vSuper) - 2;
    assert( LeftBound <= RightBound );
    if ( LeftBound == RightBound )
        return;
    // get the two last nodes
    pObj1 = (Hop_Obj_t *)Vec_PtrEntry( vSuper, RightBound + 1 );
    pObj2 = (Hop_Obj_t *)Vec_PtrEntry( vSuper, RightBound     );
    if ( Hop_Regular(pObj1) == p->pConst1 || Hop_Regular(pObj2) == p->pConst1 )
        return;
    // find the first node that can be shared
    for ( i = RightBound; i >= LeftBound; i-- )
    {
        pObj3 = (Hop_Obj_t *)Vec_PtrEntry( vSuper, i );
        if ( Hop_Regular(pObj3) == p->pConst1 )
        {
            Vec_PtrWriteEntry( vSuper, i,          pObj2 );
            Vec_PtrWriteEntry( vSuper, RightBound, pObj3 );
            return;
        }
        pGhost = Hop_ObjCreateGhost( p, pObj1, pObj3, fExor? AIG_EXOR : AIG_AND );
        if ( Hop_TableLookup( p, pGhost ) )
        {
            if ( pObj3 == pObj2 )
                return;
            Vec_PtrWriteEntry( vSuper, i,          pObj2 );
            Vec_PtrWriteEntry( vSuper, RightBound, pObj3 );
            return;
        }
    }
/*
    // we did not find the node to share, randomize choice
    {
        int Choice = rand() % (RightBound - LeftBound + 1);
        pObj3 = Vec_PtrEntry( vSuper, LeftBound + Choice );
        if ( pObj3 == pObj2 )
            return;
        Vec_PtrWriteEntry( vSuper, LeftBound + Choice, pObj2 );
        Vec_PtrWriteEntry( vSuper, RightBound,         pObj3 );
    }
*/
}

void Hop_NodeBalancePushUniqueOrderByLevel ( Vec_Ptr_t *  vStore, Hop_Obj_t *  pObj  )

static

Function*************************************************************

Synopsis [Inserts a new node in the order by levels.]

Description []

SideEffects []

SeeAlso []

Definition at line 376 of file hopBalance.c.

{
    Hop_Obj_t * pObj1, * pObj2;
    int i;
    if ( Vec_PtrPushUnique(vStore, pObj) )
        return;
    // find the p of the node
    for ( i = vStore->nSize-1; i > 0; i-- )
    {
        pObj1 = (Hop_Obj_t *)vStore->pArray[i  ];
        pObj2 = (Hop_Obj_t *)vStore->pArray[i-1];
        if ( Hop_ObjLevel(Hop_Regular(pObj1)) <= Hop_ObjLevel(Hop_Regular(pObj2)) )
            break;
        vStore->pArray[i  ] = pObj2;
        vStore->pArray[i-1] = pObj1;
    }
}

int Hop_NodeCompareLevelsDecrease	(	Hop_Obj_t **	pp1,
		Hop_Obj_t **	pp2
	)

Function*************************************************************

Synopsis [Procedure used for sorting the nodes in decreasing order of levels.]

Description []

SideEffects []

SeeAlso []

Definition at line 217 of file hopBalance.c.

{
    int Diff = Hop_ObjLevel(Hop_Regular(*pp1)) - Hop_ObjLevel(Hop_Regular(*pp2));
    if ( Diff > 0 )
        return -1;
    if ( Diff < 0 ) 
        return 1;
    Diff = Hop_Regular(*pp1)->Id - Hop_Regular(*pp2)->Id;
    if ( Diff > 0 )
        return -1;
    if ( Diff < 0 ) 
        return 1;
    return 0; 
}