mirror of https://github.com/YosysHQ/abc.git
Exploration of functions.
This commit is contained in:
Alan Mishchenko
parent
416f300d9d
commit
3ba93e3b0f
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@ -426,7 +426,7 @@ void Abc_EnumerateFunctions( int nDecMax )
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SeeAlso []
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***********************************************************************/
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#define ABC_ENUM_MAX 32
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#define ABC_ENUM_MAX 16
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static word s_Truths6[6] = {
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ABC_CONST(0xAAAAAAAAAAAAAAAA),
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ABC_CONST(0xCCCCCCCCCCCCCCCC),
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@ -441,6 +441,7 @@ struct Abc_EnuMan_t_
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int nVars; // support size
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int nVarsFree; // number of PIs used
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int fVerbose; // verbose flag
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int fUseXor; // using XOR gate
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int nNodeMax; // the max number of nodes
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int nNodes; // current number of gates
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int nTops; // the number of fanoutless gates
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@ -448,16 +449,14 @@ struct Abc_EnuMan_t_
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int pFans1[ABC_ENUM_MAX]; // fanins
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int fCompl0[ABC_ENUM_MAX]; // complements
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int fCompl1[ABC_ENUM_MAX]; // complements
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int Polar[ABC_ENUM_MAX]; // polarity
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int pRefs[ABC_ENUM_MAX]; // references
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int pLevel[ABC_ENUM_MAX]; // level
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word pTruths[ABC_ENUM_MAX]; // truth tables
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word nTries; // attempts to build a gate
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word nBuilds; // actually built gates
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word nFinished; // finished structures
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};
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static inline int Abc_EnumEquiv( word a, word b )
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{
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return a == b || a == ~b;
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}
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static inline void Abc_EnumRef( Abc_EnuMan_t * p, int i )
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{
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assert( p->pRefs[i] >= 0 );
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@ -491,151 +490,182 @@ static inline void Abc_EnumPrintOne( Abc_EnuMan_t * p )
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int i;
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Kit_DsdPrintFromTruth( (unsigned *)(p->pTruths + p->nNodes - 1), p->nVars );
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for ( i = p->nVars; i < p->nNodes; i++ )
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printf( " %c=%s%c%s%c", 'a'+i, p->fCompl0[i]?"!":"", 'a'+p->pFans0[i], p->fCompl1[i]?"!":"", 'a'+p->pFans1[i] );
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if ( p->Polar[i] == 4 )
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printf( " %c=%c+%c", 'a'+i, 'a'+p->pFans0[i], 'a'+p->pFans1[i] );
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else
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printf( " %c=%s%c%s%c", 'a'+i, p->fCompl0[i]?"!":"", 'a'+p->pFans0[i], p->fCompl1[i]?"!":"", 'a'+p->pFans1[i] );
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printf( "\n" );
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}
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void Abc_EnumerateFuncs_rec( Abc_EnuMan_t * p )
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/**Function*************************************************************
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Synopsis []
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Description []
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SideEffects []
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SeeAlso []
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***********************************************************************/
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static inline int Abc_EnumEquiv( word a, word b )
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{
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word uTruth;
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word * pTruth = p->pTruths;
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int f = p->nVarsFree;
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return a == b || a == ~b;
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}
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static inline int Abc_EnumerateFilter( Abc_EnuMan_t * p )
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{
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int fUseFull = 1;
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int n = p->nNodes;
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int i, k, c0, c1, t, a, b;
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p->nBuilds++;
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// terminate when enough and no new tops
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if ( n == p->nNodeMax && p->nTops == 1 )
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int i = p->pFans0[n];
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int k = p->pFans1[n], t;
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word * pTruths = p->pTruths;
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word uTruth = pTruths[n];
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assert( i < k );
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// skip constants
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if ( Abc_EnumEquiv(uTruth, 0) )
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return 1;
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// skip equal ones
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for ( t = 0; t < n; t++ )
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if ( Abc_EnumEquiv(uTruth, pTruths[t]) )
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return 1;
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if ( fUseFull )
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{
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// skip those that can be derived by any pair
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int a, b;
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for ( a = 0; a <= i; a++ )
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for ( b = a + 1; b <= k; b++ )
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{
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if ( a == i && b == k )
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continue;
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if ( Abc_EnumEquiv(uTruth, pTruths[a] & pTruths[b]) )
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return 1;
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if ( Abc_EnumEquiv(uTruth, pTruths[a] & ~pTruths[b]) )
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return 1;
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if ( Abc_EnumEquiv(uTruth, ~pTruths[a] & pTruths[b]) )
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return 1;
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if ( Abc_EnumEquiv(uTruth, ~pTruths[a] & ~pTruths[b]) )
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return 1;
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if ( p->fUseXor && Abc_EnumEquiv(uTruth, pTruths[a] ^ pTruths[b]) )
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return 1;
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}
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}
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else
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{
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// skip those that can be derived by fanin and any other one in the cone
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int uTruthI = p->fCompl0[n] ? ~pTruths[i] : pTruths[i];
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int uTruthK = p->fCompl1[n] ? ~pTruths[k] : pTruths[k];
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assert( p->fUseXor == 0 );
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for ( t = 0; t < k; t++ )
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if ( Abc_EnumEquiv(uTruth, pTruths[t] & uTruthI) || Abc_EnumEquiv(uTruth, ~pTruths[t] & uTruthI) )
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return 1;
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for ( t = 0; t < i; t++ )
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if ( Abc_EnumEquiv(uTruth, pTruths[t] & uTruthK) || Abc_EnumEquiv(uTruth, ~pTruths[t] & uTruthK) )
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return 1;
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}
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return 0;
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}
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void Abc_EnumerateFuncs_rec( Abc_EnuMan_t * p, int fNew, int iNode1st ) // the first node on the last level
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{
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if ( p->nNodes == p->nNodeMax )
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{
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assert( p->nTops == 1 );
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if ( p->fVerbose )
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Abc_EnumPrintOne( p );
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p->nFinished++;
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return;
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}
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if ( p->nTops > p->nNodeMax - n + 1 )
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return;
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assert( n < p->nNodeMax );
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// try new gates with two inputs
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if ( f >= 2 )
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{
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p->pFans0[n] = f - 2;
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p->pFans1[n] = f - 1;
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p->fCompl0[n] = 0;
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p->fCompl1[n] = 0;
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p->pTruths[n] = pTruth[f - 2] & pTruth[f - 1];
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p->nVarsFree -= 2;
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Abc_EnumRefNode( p, n );
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Abc_EnumerateFuncs_rec( p );
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Abc_EnumDerefNode( p, n );
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p->nVarsFree += 2;
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return;
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}
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// try new gates with one input
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if ( f > 0 )
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int i, k, c, cLim = 4 + p->fUseXor, n = p->nNodes;
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int nRefedFans = p->nNodeMax - n + 1 - p->nTops;
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int high0 = fNew ? iNode1st : p->pFans1[n-1];
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int high1 = fNew ? n : iNode1st;
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int low0 = fNew ? 0 : p->pFans0[n-1];
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int c0 = fNew ? 0 : p->Polar[n-1];
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int Level = p->pLevel[high0];
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assert( p->nTops > 0 && p->nTops <= p->nNodeMax - n + 1 );
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// go through nodes
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for ( k = high0; k < high1; k++ )
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{
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for ( i = f; i < n; i++ )
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for ( c0 = 0; c0 < 2; c0++ )
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if ( nRefedFans == 0 && p->pRefs[k] > 0 )
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continue;
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if ( p->pRefs[k] > 0 )
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nRefedFans--;
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assert( nRefedFans >= 0 );
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// try second fanin
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for ( i = (k == high0) ? low0 : 0; i < k; i++ )
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{
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uTruth = pTruth[f - 1] & (c0 ? ~pTruth[i] : pTruth[i]);
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p->pFans0[n] = f - 1;
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p->pFans1[n] = i;
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p->fCompl0[n] = 0;
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p->fCompl1[n] = c0;
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p->pTruths[n] = uTruth;
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p->nVarsFree--;
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Abc_EnumRefNode( p, n );
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Abc_EnumerateFuncs_rec( p );
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Abc_EnumDerefNode( p, n );
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p->nVarsFree++;
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}
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return;
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}
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// try new gates without inputs
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for ( i = f; i < n; i++ )
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for ( k = i+1; k < n; k++ )
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for ( c0 = 0; c0 < 2; c0++ )
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for ( c1 = 0; c1 < 2; c1++ )
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{
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uTruth = (c0 ? ~pTruth[i] : pTruth[i]) & (c1 ? ~pTruth[k] : pTruth[k]);
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// skip constants
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if ( uTruth == 0 || ~uTruth == 0 )
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continue;
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// skip equal ones
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for ( t = f; t < n; t++ )
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if ( uTruth == p->pTruths[t] || ~uTruth == p->pTruths[t] )
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break;
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if ( t < n )
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continue;
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// skip those that can be derived by fanin and any other one in the cone
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for ( a = f; a < i; a++ )
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if ( Abc_EnumEquiv(uTruth, p->pTruths[a] & p->pTruths[k]) || Abc_EnumEquiv(uTruth, ~p->pTruths[a] & p->pTruths[k]) )
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break;
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if ( a < i )
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continue;
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for ( b = f; b < k; b++ )
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if ( Abc_EnumEquiv(uTruth, p->pTruths[b] & p->pTruths[i]) || Abc_EnumEquiv(uTruth, ~p->pTruths[b] & p->pTruths[i]) )
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break;
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if ( b < k )
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continue;
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/*
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// skip those that can be derived by any two in the cone, except the top ones
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for ( a = f; a <= i; a++ )
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{
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word uTemp;
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for ( b = a + 1; b <= k; b++ )
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if ( nRefedFans == 0 && p->pRefs[i] > 0 )
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continue;
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if ( Level == 0 && p->pRefs[i] == 0 && p->pRefs[k] == 0 && (i+1 != k || (i > 0 && p->pRefs[i-1] == 0)) ) // NPN
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continue;
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if ( p->pLevel[k] == 0 && p->pRefs[k] == 0 && p->pRefs[i] != 0 && k > 0 && p->pRefs[k-1] == 0 ) // NPN
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continue;
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// if ( p->pLevel[i] == 0 && p->pRefs[i] == 0 && p->pRefs[k] != 0 && i > 0 && p->pRefs[i-1] == 0 ) // NPN
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// continue;
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// try four polarities
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for ( c = (k == high0 && i == low0 && !fNew) ? c0 + 1 : 0; c < cLim; c++ )
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{
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if ( a == i && b == k )
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if ( p->pLevel[i] == 0 && p->pRefs[i] == 0 && (c & 1) == 1 ) // NPN
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continue;
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uTemp = p->pTruths[a] & p->pTruths[b];
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if ( uTruth == uTemp || ~uTruth == uTemp )
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break;
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uTemp = p->pTruths[a] & ~p->pTruths[b];
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if ( uTruth == uTemp || ~uTruth == uTemp )
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break;
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uTemp = ~p->pTruths[a] & p->pTruths[b];
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if ( uTruth == uTemp || ~uTruth == uTemp )
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break;
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uTemp = ~p->pTruths[a] & ~p->pTruths[b];
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if ( uTruth == uTemp || ~uTruth == uTemp )
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break;
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if ( p->pLevel[k] == 0 && p->pRefs[k] == 0 && (c & 2) == 2 ) // NPN
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continue;
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p->nTries++;
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// create node
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assert( i < k );
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p->pFans0[n] = i;
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p->pFans1[n] = k;
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p->fCompl0[n] = c & 1;
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p->fCompl1[n] = (c >> 1) & 1;
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p->Polar[n] = c;
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if ( c == 4 )
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p->pTruths[n] = p->pTruths[i] ^ p->pTruths[k];
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else
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p->pTruths[n] = ((c & 1) ? ~p->pTruths[i] : p->pTruths[i]) & ((c & 2) ? ~p->pTruths[k] : p->pTruths[k]);
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if ( Abc_EnumerateFilter(p) )
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continue;
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p->nBuilds++;
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assert( Level == Abc_MaxInt(p->pLevel[i], p->pLevel[k]) );
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p->pLevel[n] = Level + 1;
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Abc_EnumRefNode( p, n );
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Abc_EnumerateFuncs_rec( p, 0, fNew ? n : iNode1st );
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Abc_EnumDerefNode( p, n );
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assert( n == p->nNodes );
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}
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if ( b <= k )
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break;
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}
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if ( a <= i )
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continue;
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*/
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p->pFans0[n] = i;
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p->pFans1[n] = k;
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p->fCompl0[n] = c0;
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p->fCompl1[n] = c1;
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p->pTruths[n] = uTruth;
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Abc_EnumRefNode( p, n );
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Abc_EnumerateFuncs_rec( p );
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Abc_EnumDerefNode( p, n );
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if ( p->pRefs[k] > 0 )
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nRefedFans++;
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}
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if ( fNew )
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return;
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// start a new level
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Abc_EnumerateFuncs_rec( p, 1, iNode1st );
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}
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}
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void Abc_EnumerateFuncs( int nVars, int nGates, int fVerbose )
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{
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abctime clk = Abc_Clock();
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Abc_EnuMan_t P, * p = &P; int i;
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Abc_EnuMan_t P, * p = &P;
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int i, n = nVars;
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if ( nVars > nGates + 1 )
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{
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printf( "The gate count %d is not enough to have functions with %d inputs.\n", nGates, nVars );
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return;
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}
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assert( nVars >= 3 && nVars <= 6 );
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assert( nGates > 0 && nVars + nGates < 16 );
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assert( nVars >= 2 && nVars <= 6 );
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assert( nGates > 0 && nVars + nGates < ABC_ENUM_MAX );
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memset( p, 0, sizeof(Abc_EnuMan_t) );
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p->fVerbose = fVerbose;
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p->fUseXor = 1;
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p->nVars = nVars;
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p->nVarsFree = nVars;
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p->nNodeMax = nVars + nGates;
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p->nNodes = nVars;
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p->nTops = nVars;
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for ( i = 0; i < nVars; i++ )
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p->pTruths[i] = s_Truths6[i];
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Abc_EnumerateFuncs_rec( p );
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Abc_EnumerateFuncs_rec( p, 1, 0 );
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assert( p->nNodes == nVars );
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assert( p->nTops == nVars );
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// report statistics
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printf( "Vars = %d. Gates = %d. Tries = %u. Builds = %u. Finished = %d. ",
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nVars, nGates, (unsigned)p->nTries, (unsigned)p->nBuilds, (unsigned)p->nFinished );
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Abc_PrintTime( 1, "Time", Abc_Clock() - clk );
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