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Diffstat (limited to 'src/base/seq/seqAigIter.c')
| -rw-r--r-- | src/base/seq/seqAigIter.c | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/src/base/seq/seqAigIter.c b/src/base/seq/seqAigIter.c new file mode 100644 index 00000000..9b423d32 --- /dev/null +++ b/src/base/seq/seqAigIter.c @@ -0,0 +1,245 @@ +/**CFile**************************************************************** + + FileName [seqRetIter.c] + + SystemName [ABC: Logic synthesis and verification system.] + + PackageName [Construction and manipulation of sequential AIGs.] + + Synopsis [The iterative L-Value computation for retiming procedures.] + + Author [Alan Mishchenko] + + Affiliation [UC Berkeley] + + Date [Ver. 1.0. Started - June 20, 2005.] + + Revision [$Id: seqRetIter.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $] + +***********************************************************************/ + +#include "seqInt.h" + +//////////////////////////////////////////////////////////////////////// +/// DECLARATIONS /// +//////////////////////////////////////////////////////////////////////// + +// the internal procedures +static int Seq_RetimeSearch_rec( Abc_Ntk_t * pNtk, int FiMin, int FiMax, int fVerbose ); +static int Seq_RetimeForPeriod( Abc_Ntk_t * pNtk, int Fi, int fVerbose ); +static int Seq_RetimeNodeUpdateLValue( Abc_Obj_t * pObj, int Fi ); + +//////////////////////////////////////////////////////////////////////// +/// FUNCTION DEFINITIONS /// +//////////////////////////////////////////////////////////////////////// + +/**Function************************************************************* + + Synopsis [Retimes AIG for optimal delay using Pan's algorithm.] + + Description [] + + SideEffects [] + + SeeAlso [] + +***********************************************************************/ +void Seq_AigRetimeDelayLags( Abc_Ntk_t * pNtk, int fVerbose ) +{ + Abc_Seq_t * p = pNtk->pManFunc; + Abc_Obj_t * pNode; + int i, FiMax, FiBest, RetValue; + char NodeLag; + + assert( Abc_NtkIsSeq( pNtk ) ); + + // get the upper bound on the clock period + FiMax = 2 + Seq_NtkLevelMax(pNtk); + + // make sure this clock period is feasible + assert( Seq_RetimeForPeriod( pNtk, FiMax, fVerbose ) ); + + // search for the optimal clock period between 0 and nLevelMax + FiBest = Seq_RetimeSearch_rec( pNtk, 0, FiMax, fVerbose ); + + // recompute the best l-values + RetValue = Seq_RetimeForPeriod( pNtk, FiBest, fVerbose ); + assert( RetValue ); + + // write the retiming lags + Vec_StrFill( p->vLags, p->nSize, 0 ); + Abc_AigForEachAnd( pNtk, pNode, i ) + { + NodeLag = Seq_NodeComputeLag( Seq_NodeGetLValue(pNode), FiBest ); + Seq_NodeSetLag( pNode, NodeLag ); + } +/* + { + Abc_Obj_t * pFanin, * pFanout; + pNode = Abc_NtkObj( pNtk, 823 ); + printf( "Node %d. Lag = %d. LValue = %d. Latches = (%d,%d) (%d,%d).\n", pNode->Id, Seq_NodeGetLag(pNode), Seq_NodeGetLValue(pNode), + Seq_ObjFaninL0(pNode), Seq_ObjFaninL1(pNode), Seq_ObjFanoutL(pNode, Abc_NtkObj(pNtk, 826)), Seq_ObjFanoutL(pNode, Abc_NtkObj(pNtk, 1210)) ); + pFanin = Abc_ObjFanin0( pNode ); + printf( "Fanin %d. Lag = %d. LValue = %d. Latches = (%d,%d)\n", pFanin->Id, Seq_NodeGetLag(pFanin), Seq_NodeGetLValue(pFanin), + Seq_ObjFaninL0(pFanin), Seq_ObjFaninL1(pFanin) ); + pFanin = Abc_ObjFanin1( pNode ); + printf( "Fanin %d. Lag = %d. LValue = %d.\n", pFanin->Id, Seq_NodeGetLag(pFanin), Seq_NodeGetLValue(pFanin) ); + Abc_ObjForEachFanout( pNode, pFanout, i ) + printf( "Fanout %d. Lag = %d. LValue = %d.\n", pFanout->Id, Seq_NodeGetLag(pFanout), Seq_NodeGetLValue(pFanout) ); + Abc_ObjForEachFanout( Abc_ObjFanin0(pNode), pFanout, i ) + printf( "Fanout %d. Lag = %d. LValue = %d.\n", pFanout->Id, Seq_NodeGetLag(pFanout), Seq_NodeGetLValue(pFanout) ); + } +*/ + + // print the result + if ( fVerbose ) + printf( "The best clock period is %3d.\n", FiBest ); + +/* + printf( "LValues : " ); + Abc_AigForEachAnd( pNtk, pNode, i ) + printf( "%d=%d ", i, Seq_NodeGetLValue(pNode) ); + printf( "\n" ); + printf( "Lags : " ); + Abc_AigForEachAnd( pNtk, pNode, i ) + if ( Vec_StrEntry(p->vLags,i) != 0 ) + printf( "%d=%d(%d)(%d) ", i, Vec_StrEntry(p->vLags,i), Seq_NodeGetLValue(pNode), Seq_NodeGetLValue(pNode) - FiBest * Vec_StrEntry(p->vLags,i) ); + printf( "\n" ); +*/ +} + +/**Function************************************************************* + + Synopsis [Performs binary search for the optimal clock period.] + + Description [Assumes that FiMin is infeasible while FiMax is feasible.] + + SideEffects [] + + SeeAlso [] + +***********************************************************************/ +int Seq_RetimeSearch_rec( Abc_Ntk_t * pNtk, int FiMin, int FiMax, int fVerbose ) +{ + int Median; + assert( FiMin < FiMax ); + if ( FiMin + 1 == FiMax ) + return FiMax; + Median = FiMin + (FiMax - FiMin)/2; + if ( Seq_RetimeForPeriod( pNtk, Median, fVerbose ) ) + return Seq_RetimeSearch_rec( pNtk, FiMin, Median, fVerbose ); // Median is feasible + else + return Seq_RetimeSearch_rec( pNtk, Median, FiMax, fVerbose ); // Median is infeasible +} + +/**Function************************************************************* + + Synopsis [Returns 1 if retiming with this clock period is feasible.] + + Description [] + + SideEffects [] + + SeeAlso [] + +***********************************************************************/ +int Seq_RetimeForPeriod( Abc_Ntk_t * pNtk, int Fi, int fVerbose ) +{ + Abc_Seq_t * p = pNtk->pManFunc; + Abc_Obj_t * pObj; + int i, c, RetValue, fChange, Counter; + char * pReason = ""; + + // set l-values of all nodes to be minus infinity + Vec_IntFill( p->vLValues, p->nSize, -ABC_INFINITY ); + + // set l-values of constants and PIs + pObj = Abc_NtkObj( pNtk, 0 ); + Seq_NodeSetLValue( pObj, 0 ); + Abc_NtkForEachPi( pNtk, pObj, i ) + Seq_NodeSetLValue( pObj, 0 ); + + // update all values iteratively + Counter = 0; + for ( c = 0; c < p->nMaxIters; c++ ) + { + fChange = 0; + Abc_AigForEachAnd( pNtk, pObj, i ) + { + Counter++; + if ( Seq_NodeCutMan(pObj) ) + RetValue = Seq_FpgaNodeUpdateLValue( pObj, Fi ); + else + RetValue = Seq_RetimeNodeUpdateLValue( pObj, Fi ); + if ( RetValue == SEQ_UPDATE_YES ) + fChange = 1; + } + Abc_NtkForEachPo( pNtk, pObj, i ) + { + if ( Seq_NodeCutMan(pObj) ) + RetValue = Seq_FpgaNodeUpdateLValue( pObj, Fi ); + else + RetValue = Seq_RetimeNodeUpdateLValue( pObj, Fi ); + if ( RetValue == SEQ_UPDATE_FAIL ) + break; + } + if ( RetValue == SEQ_UPDATE_FAIL ) + break; + if ( fChange == 0 ) + break; + } + if ( c == p->nMaxIters ) + { + RetValue = SEQ_UPDATE_FAIL; + pReason = "(timeout)"; + } + else + c++; + // report the results + if ( fVerbose ) + { + if ( RetValue == SEQ_UPDATE_FAIL ) + printf( "Period = %3d. Iterations = %3d. Updates = %10d. Infeasible %s\n", Fi, c, Counter, pReason ); + else + printf( "Period = %3d. Iterations = %3d. Updates = %10d. Feasible\n", Fi, c, Counter ); + } + return RetValue != SEQ_UPDATE_FAIL; +} + +/**Function************************************************************* + + Synopsis [Computes the l-value of the node.] + + Description [The node can be internal or a PO.] + + SideEffects [] + + SeeAlso [] + +***********************************************************************/ +int Seq_RetimeNodeUpdateLValue( Abc_Obj_t * pObj, int Fi ) +{ + int lValueNew, lValueOld, lValue0, lValue1; + assert( !Abc_ObjIsPi(pObj) ); + assert( Abc_ObjFaninNum(pObj) > 0 ); + lValue0 = Seq_NodeGetLValue(Abc_ObjFanin0(pObj)) - Fi * Seq_ObjFaninL0(pObj); + if ( Abc_ObjIsPo(pObj) ) + return (lValue0 > Fi)? SEQ_UPDATE_FAIL : SEQ_UPDATE_NO; + if ( Abc_ObjFaninNum(pObj) == 2 ) + lValue1 = Seq_NodeGetLValue(Abc_ObjFanin1(pObj)) - Fi * Seq_ObjFaninL1(pObj); + else + lValue1 = -ABC_INFINITY; + lValueNew = 1 + ABC_MAX( lValue0, lValue1 ); + lValueOld = Seq_NodeGetLValue(pObj); +// if ( lValueNew == lValueOld ) + if ( lValueNew <= lValueOld ) + return SEQ_UPDATE_NO; + Seq_NodeSetLValue( pObj, lValueNew ); + return SEQ_UPDATE_YES; +} + +//////////////////////////////////////////////////////////////////////// +/// END OF FILE /// +//////////////////////////////////////////////////////////////////////// + + |