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/**CFile****************************************************************
FileName [sbd.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [SAT-based optimization using internal don't-cares.]
Synopsis []
Author [Alan Mishchenko]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - June 20, 2005.]
Revision [$Id: sbd.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
***********************************************************************/
#include "sbdInt.h"
ABC_NAMESPACE_IMPL_START
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Constructs SAT solver for the window.]
Description [The window for the pivot node (Pivot) is represented as
a DFS ordered array of objects (vWinObjs) whose indexed in the array
(which will be used as SAT variables) are given in array vObj2Var.
The TFO nodes are listed as the last ones in vWinObjs. The root nodes
are labeled with Abc_LitIsCompl() in vTfo and also given in vRoots.]
SideEffects []
SeeAlso []
***********************************************************************/
sat_solver * Sbd_ManSatSolver( sat_solver * pSat, Gia_Man_t * p, Vec_Int_t * vMirrors, int Pivot, Vec_Int_t * vWinObjs, Vec_Int_t * vObj2Var, Vec_Int_t * vTfo, Vec_Int_t * vRoots )
{
Gia_Obj_t * pObj;
int i, iLit = 1, iObj, Fan0, Fan1, Lit0m, Lit1m, Node, fCompl0, fCompl1, RetValue;
int TfoStart = Vec_IntSize(vWinObjs) - Vec_IntSize(vTfo);
int PivotVar = Vec_IntEntry(vObj2Var, Pivot);
//Vec_IntPrint( vWinObjs );
//Vec_IntPrint( vTfo );
//Vec_IntPrint( vRoots );
// create SAT solver
if ( pSat == NULL )
pSat = sat_solver_new();
else
sat_solver_restart( pSat );
sat_solver_setnvars( pSat, Vec_IntSize(vWinObjs) + Vec_IntSize(vTfo) + Vec_IntSize(vRoots) + 32 );
// create constant 0 clause
sat_solver_addclause( pSat, &iLit, &iLit + 1 );
// add clauses for all nodes
Vec_IntForEachEntryStart( vWinObjs, iObj, i, 1 )
{
pObj = Gia_ManObj( p, iObj );
if ( Gia_ObjIsCi(pObj) )
continue;
assert( Gia_ObjIsAnd(pObj) );
assert( Vec_IntEntry( vMirrors, iObj ) < 0 );
Node = Vec_IntEntry( vObj2Var, iObj );
Lit0m = Vec_IntEntry( vMirrors, Gia_ObjFaninId0(pObj, iObj) );
Lit1m = Vec_IntEntry( vMirrors, Gia_ObjFaninId1(pObj, iObj) );
Fan0 = Lit0m >= 0 ? Abc_Lit2Var(Lit0m) : Gia_ObjFaninId0(pObj, iObj);
Fan1 = Lit1m >= 0 ? Abc_Lit2Var(Lit1m) : Gia_ObjFaninId1(pObj, iObj);
Fan0 = Vec_IntEntry( vObj2Var, Fan0 );
Fan1 = Vec_IntEntry( vObj2Var, Fan1 );
fCompl0 = Gia_ObjFaninC0(pObj) ^ (Lit0m >= 0 && Abc_LitIsCompl(Lit0m));
fCompl1 = Gia_ObjFaninC1(pObj) ^ (Lit1m >= 0 && Abc_LitIsCompl(Lit1m));
if ( Gia_ObjIsXor(pObj) )
sat_solver_add_xor( pSat, Node, Fan0, Fan1, fCompl0 ^ fCompl1 );
else
sat_solver_add_and( pSat, Node, Fan0, Fan1, fCompl0, fCompl1, 0 );
}
// add second clauses for the TFO
Vec_IntForEachEntryStart( vWinObjs, iObj, i, TfoStart )
{
pObj = Gia_ManObj( p, iObj );
assert( Gia_ObjIsAnd(pObj) );
assert( Vec_IntEntry( vMirrors, iObj ) < 0 );
Node = Vec_IntEntry( vObj2Var, iObj ) + Vec_IntSize(vTfo);
Lit0m = Vec_IntEntry( vMirrors, Gia_ObjFaninId0(pObj, iObj) );
Lit1m = Vec_IntEntry( vMirrors, Gia_ObjFaninId1(pObj, iObj) );
Fan0 = Lit0m >= 0 ? Abc_Lit2Var(Lit0m) : Gia_ObjFaninId0(pObj, iObj);
Fan1 = Lit1m >= 0 ? Abc_Lit2Var(Lit1m) : Gia_ObjFaninId1(pObj, iObj);
Fan0 = Vec_IntEntry( vObj2Var, Fan0 );
Fan1 = Vec_IntEntry( vObj2Var, Fan1 );
Fan0 = Fan0 < TfoStart ? Fan0 : Fan0 + Vec_IntSize(vTfo);
Fan1 = Fan1 < TfoStart ? Fan1 : Fan1 + Vec_IntSize(vTfo);
fCompl0 = Gia_ObjFaninC0(pObj) ^ (Fan0 == PivotVar) ^ (Lit0m >= 0 && Abc_LitIsCompl(Lit0m));
fCompl1 = Gia_ObjFaninC1(pObj) ^ (Fan1 == PivotVar) ^ (Lit1m >= 0 && Abc_LitIsCompl(Lit1m));
if ( Gia_ObjIsXor(pObj) )
sat_solver_add_xor( pSat, Node, Fan0, Fan1, fCompl0 ^ fCompl1 );
else
sat_solver_add_and( pSat, Node, Fan0, Fan1, fCompl0, fCompl1, 0 );
}
if ( Vec_IntSize(vRoots) > 0 )
{
// create XOR clauses for the roots
int nVars = Vec_IntSize(vWinObjs) + Vec_IntSize(vTfo);
Vec_Int_t * vFaninVars = Vec_IntAlloc( Vec_IntSize(vRoots) );
Vec_IntForEachEntry( vRoots, iObj, i )
{
assert( Vec_IntEntry( vMirrors, iObj ) < 0 );
Node = Vec_IntEntry( vObj2Var, iObj );
Vec_IntPush( vFaninVars, Abc_Var2Lit(nVars, 0) );
sat_solver_add_xor( pSat, Node, Node + Vec_IntSize(vTfo), nVars++, 0 );
}
// make OR clause for the last nRoots variables
RetValue = sat_solver_addclause( pSat, Vec_IntArray(vFaninVars), Vec_IntLimit(vFaninVars) );
Vec_IntFree( vFaninVars );
if ( RetValue == 0 )
{
sat_solver_delete( pSat );
return NULL;
}
assert( sat_solver_nvars(pSat) == nVars + 32 );
}
// finalize
RetValue = sat_solver_simplify( pSat );
if ( RetValue == 0 )
{
sat_solver_delete( pSat );
return NULL;
}
return pSat;
}
/**Function*************************************************************
Synopsis [Solves one SAT problem.]
Description [Computes node function for PivotVar with fanins in vDivVars
using don't-care represented in the SAT solver. Uses array vValues to
return the values of the first Vec_IntSize(vValues) SAT variables in case
the implementation of the node with the given fanins does not exist.]
SideEffects []
SeeAlso []
***********************************************************************/
word Sbd_ManSolve( sat_solver * pSat, int PivotVar, int FreeVar, Vec_Int_t * vDivVars, Vec_Int_t * vValues, Vec_Int_t * vTemp )
{
int nBTLimit = 0;
word uCube, uTruth = 0;
int status, i, iVar, nFinal, * pFinal, pLits[2], nIter = 0;
assert( FreeVar < sat_solver_nvars(pSat) );
pLits[0] = Abc_Var2Lit( PivotVar, 0 ); // F = 1
pLits[1] = Abc_Var2Lit( FreeVar, 0 ); // iNewLit
while ( 1 )
{
// find onset minterm
status = sat_solver_solve( pSat, pLits, pLits + 2, nBTLimit, 0, 0, 0 );
if ( status == l_Undef )
return SBD_SAT_UNDEC;
if ( status == l_False )
return uTruth;
assert( status == l_True );
// remember variable values
for ( i = 0; i < Vec_IntSize(vValues); i++ )
Vec_IntWriteEntry( vValues, i, 2*sat_solver_var_value(pSat, i) );
// collect divisor literals
Vec_IntClear( vTemp );
Vec_IntPush( vTemp, Abc_LitNot(pLits[0]) ); // F = 0
Vec_IntForEachEntry( vDivVars, iVar, i )
Vec_IntPush( vTemp, sat_solver_var_literal(pSat, iVar) );
// check against offset
status = sat_solver_solve( pSat, Vec_IntArray(vTemp), Vec_IntArray(vTemp) + Vec_IntSize(vTemp), nBTLimit, 0, 0, 0 );
if ( status == l_Undef )
return SBD_SAT_UNDEC;
if ( status == l_True )
break;
assert( status == l_False );
// compute cube and add clause
nFinal = sat_solver_final( pSat, &pFinal );
uCube = ~(word)0;
Vec_IntClear( vTemp );
Vec_IntPush( vTemp, Abc_LitNot(pLits[1]) ); // NOT(iNewLit)
for ( i = 0; i < nFinal; i++ )
{
if ( pFinal[i] == pLits[0] )
continue;
Vec_IntPush( vTemp, pFinal[i] );
iVar = Vec_IntFind( vDivVars, Abc_Lit2Var(pFinal[i]) ); assert( iVar >= 0 );
uCube &= Abc_LitIsCompl(pFinal[i]) ? s_Truths6[iVar] : ~s_Truths6[iVar];
}
uTruth |= uCube;
status = sat_solver_addclause( pSat, Vec_IntArray(vTemp), Vec_IntArray(vTemp) + Vec_IntSize(vTemp) );
assert( status );
nIter++;
}
assert( status == l_True );
// store the counter-example
for ( i = 0; i < Vec_IntSize(vValues); i++ )
Vec_IntAddToEntry( vValues, i, sat_solver_var_value(pSat, i) );
for ( i = 0; i < Vec_IntSize(vValues); i++ )
Vec_IntAddToEntry( vValues, i, 0xC );
/*
// reduce the counter example
for ( n = 0; n < 2; n++ )
{
Vec_IntClear( vTemp );
Vec_IntPush( vTemp, Abc_Var2Lit(PivotVar, n) ); // n = 0 => F = 1 (expanding offset against onset)
for ( i = 0; i < Vec_IntSize(vValues); i++ )
Vec_IntPush( vTemp, Abc_Var2Lit(i, !((Vec_IntEntry(vValues, i) >> n) & 1)) );
status = sat_solver_solve( pSat, Vec_IntArray(vTemp), Vec_IntArray(vTemp) + Vec_IntSize(vTemp), nBTLimit, 0, 0, 0 );
assert( status == l_False );
// compute cube and add clause
nFinal = sat_solver_final( pSat, &pFinal );
for ( i = 0; i < nFinal; i++ )
if ( Abc_Lit2Var(pFinal[i]) != PivotVar )
Vec_IntAddToEntry( vValues, Abc_Lit2Var(pFinal[i]), 1 << (n+2) );
}
*/
return SBD_SAT_SAT;
}
/**Function*************************************************************
Synopsis [Returns a bunch of positive/negative random care minterms.]
Description [Returns 0/1 if the functions is const 0/1.]
SideEffects []
SeeAlso []
***********************************************************************/
static void sat_solver_random_polarity(sat_solver* s)
{
int i, k;
for ( i = 0; i < s->size; i += 64 )
{
word Polar = Gia_ManRandomW(0);
for ( k = 0; k < 64 && (i << 6) + k < s->size; k++ )
s->polarity[(i << 6) + k] = Abc_TtGetBit(&Polar, k);
}
}
int Sbd_ManCollectConstants( sat_solver * pSat, int nCareMints[2], int PivotVar, word * pVarSims[], Vec_Int_t * vInds )
{
int nBTLimit = 0;
int i, Ind;
assert( Vec_IntSize(vInds) == nCareMints[0] + nCareMints[1] );
Vec_IntForEachEntry( vInds, Ind, i )
{
int fOffSet = (int)(i < nCareMints[0]);
int status, k, iLit = Abc_Var2Lit( PivotVar, fOffSet );
sat_solver_random_polarity( pSat );
status = sat_solver_solve( pSat, &iLit, &iLit + 1, nBTLimit, 0, 0, 0 );
if ( status == l_Undef )
return -2;
if ( status == l_False )
return fOffSet;
for ( k = 0; k <= PivotVar; k++ )
if ( Abc_TtGetBit(pVarSims[k], Ind) != sat_solver_var_value(pSat, k) )
Abc_TtXorBit(pVarSims[k], Ind);
}
return -1;
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
ABC_NAMESPACE_IMPL_END
|
