Version abc51114

1 files changed, 226 insertions, 0 deletions

diff --git a/src/base/seq/seqRetIter.c b/src/base/seq/seqRetIter.c
new file mode 100644
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+++ b/src/base/seq/seqRetIter.c
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+/**CFile****************************************************************
+
+  FileName    [seqRetIter.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Construction and manipulation of sequential AIGs.]
+
+  Synopsis    []
+
+  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_NodeUpdateLValue( Abc_Obj_t * pObj, int Fi );
+
+// node status after updating its arrival time
+enum { SEQ_UPDATE_FAIL, SEQ_UPDATE_NO, SEQ_UPDATE_YES };
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Retimes AIG for optimal delay using Pan's algorithm.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Seq_NtkSeqRetimeDelayLags( Abc_Ntk_t * pNtk, int fVerbose )
+{
+    Abc_Seq_t * p = pNtk->pManFunc;
+    Abc_Obj_t * pNode;
+    int i, FiMax, FiBest, RetValue;
+
+    assert( Abc_NtkIsSeq( pNtk ) );
+
+    // get the upper bound on the clock period
+//    FiMax = Abc_NtkNodeNum(pNtk);
+    FiMax = 0;
+    Abc_AigForEachAnd( pNtk, pNode, i )
+        if ( FiMax < (int)pNode->Level )
+            FiMax = pNode->Level;
+    FiMax += 2;
+
+    // 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 LValues
+    RetValue = Seq_RetimeForPeriod( pNtk, FiBest, fVerbose );
+    assert( RetValue );
+
+    // write the retiming lags
+    Vec_StrFill( p->vLags, p->nSize, 0 );
+    Abc_AigForEachAnd( pNtk, pNode, i )
+        Seq_NodeSetLag( pNode, (char)Seq_NodeComputeLag(Seq_NodeGetLValue(pNode), FiBest) );
+
+    // 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 for the constant 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 < 20; c++ )
+    {
+        fChange = 0;
+        Abc_NtkForEachObj( pNtk, pObj, i )
+        {
+            if ( Abc_ObjIsPi(pObj) )
+                continue;
+            if ( Abc_ObjFaninNum(pObj) == 0 )
+                continue;
+            RetValue = Seq_NodeUpdateLValue( pObj, Fi );
+            Counter++;
+            if ( RetValue == SEQ_UPDATE_FAIL )
+                break;
+            if ( RetValue == SEQ_UPDATE_NO ) 
+                continue;
+            fChange = 1;
+        }
+        if ( RetValue == SEQ_UPDATE_FAIL )
+            break;
+        if ( fChange == 0 )
+            break;
+    }
+    if ( c == 20 )
+    {
+        RetValue = SEQ_UPDATE_FAIL;
+        pReason = "(timeout)";
+    }
+
+    // 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_NodeUpdateLValue( 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 * Abc_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 * Abc_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                                ///
+////////////////////////////////////////////////////////////////////////
+
+