1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
|
/**CFile****************************************************************
FileName [abcMinBase.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [Network and node package.]
Synopsis [Makes nodes of the network minimum base.]
Author [Alan Mishchenko]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - June 20, 2005.]
Revision [$Id: abcMinBase.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
***********************************************************************/
#include "abc.h"
#include "src/misc/extra/extraBdd.h"
ABC_NAMESPACE_IMPL_START
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
static int Abc_NodeSupport( DdNode * bFunc, Vec_Str_t * vSupport, int nVars );
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Makes nodes minimum base.]
Description [Returns the number of changed nodes.]
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NtkMinimumBase( Abc_Ntk_t * pNtk )
{
Abc_Obj_t * pNode;
int i, Counter;
assert( Abc_NtkIsBddLogic(pNtk) );
Counter = 0;
Abc_NtkForEachNode( pNtk, pNode, i )
Counter += Abc_NodeMinimumBase( pNode );
return Counter;
}
/**Function*************************************************************
Synopsis [Makes one node minimum base.]
Description [Returns 1 if the node is changed.]
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NodeMinimumBase( Abc_Obj_t * pNode )
{
Vec_Str_t * vSupport;
Vec_Ptr_t * vFanins;
DdNode * bTemp;
int i, nVars;
assert( Abc_NtkIsBddLogic(pNode->pNtk) );
assert( Abc_ObjIsNode(pNode) );
// compute support
vSupport = Vec_StrAlloc( 10 );
nVars = Abc_NodeSupport( Cudd_Regular(pNode->pData), vSupport, Abc_ObjFaninNum(pNode) );
if ( nVars == Abc_ObjFaninNum(pNode) )
{
Vec_StrFree( vSupport );
return 0;
}
// remove unused fanins
vFanins = Vec_PtrAlloc( Abc_ObjFaninNum(pNode) );
Abc_NodeCollectFanins( pNode, vFanins );
for ( i = 0; i < vFanins->nSize; i++ )
if ( vSupport->pArray[i] == 0 )
Abc_ObjDeleteFanin( pNode, (Abc_Obj_t *)vFanins->pArray[i] );
assert( nVars == Abc_ObjFaninNum(pNode) );
// update the function of the node
pNode->pData = Extra_bddRemapUp( (DdManager *)pNode->pNtk->pManFunc, bTemp = (DdNode *)pNode->pData ); Cudd_Ref( (DdNode *)pNode->pData );
Cudd_RecursiveDeref( (DdManager *)pNode->pNtk->pManFunc, bTemp );
Vec_PtrFree( vFanins );
Vec_StrFree( vSupport );
return 1;
}
/**Function*************************************************************
Synopsis [Makes nodes of the network fanin-dup-ABC_FREE.]
Description [Returns the number of pairs of duplicated fanins.]
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NtkRemoveDupFanins( Abc_Ntk_t * pNtk )
{
Abc_Obj_t * pNode;
int i, Counter;
assert( Abc_NtkIsBddLogic(pNtk) );
Counter = 0;
Abc_NtkForEachNode( pNtk, pNode, i )
Counter += Abc_NodeRemoveDupFanins( pNode );
return Counter;
}
/**Function*************************************************************
Synopsis [Removes one pair of duplicated fanins if present.]
Description [Returns 1 if the node is changed.]
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NodeRemoveDupFanins_int( Abc_Obj_t * pNode )
{
Abc_Obj_t * pFanin1, * pFanin2;
int i, k;
assert( Abc_NtkIsBddLogic(pNode->pNtk) );
assert( Abc_ObjIsNode(pNode) );
// make sure fanins are not duplicated
Abc_ObjForEachFanin( pNode, pFanin2, i )
{
Abc_ObjForEachFanin( pNode, pFanin1, k )
{
if ( k >= i )
break;
if ( pFanin1 == pFanin2 )
{
DdManager * dd = (DdManager *)pNode->pNtk->pManFunc;
DdNode * bVar1 = Cudd_bddIthVar( dd, i );
DdNode * bVar2 = Cudd_bddIthVar( dd, k );
DdNode * bTrans, * bTemp;
bTrans = Cudd_bddXnor( dd, bVar1, bVar2 ); Cudd_Ref( bTrans );
pNode->pData = Cudd_bddAndAbstract( dd, bTemp = (DdNode *)pNode->pData, bTrans, bVar2 ); Cudd_Ref( (DdNode *)pNode->pData );
Cudd_RecursiveDeref( dd, bTemp );
Cudd_RecursiveDeref( dd, bTrans );
Abc_NodeMinimumBase( pNode );
return 1;
}
}
}
return 0;
}
/**Function*************************************************************
Synopsis [Removes duplicated fanins if present.]
Description [Returns the number of fanins removed.]
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NodeRemoveDupFanins( Abc_Obj_t * pNode )
{
int Counter = 0;
while ( Abc_NodeRemoveDupFanins_int(pNode) )
Counter++;
return Counter;
}
/**Function*************************************************************
Synopsis [Computes support of the node.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Abc_NodeSupport_rec( DdNode * bFunc, Vec_Str_t * vSupport )
{
if ( cuddIsConstant(bFunc) || Cudd_IsComplement(bFunc->next) )
return;
vSupport->pArray[ bFunc->index ] = 1;
Abc_NodeSupport_rec( cuddT(bFunc), vSupport );
Abc_NodeSupport_rec( Cudd_Regular(cuddE(bFunc)), vSupport );
bFunc->next = Cudd_Not(bFunc->next);
}
/**Function*************************************************************
Synopsis [Computes support of the node.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Abc_NodeSupportClear_rec( DdNode * bFunc )
{
if ( !Cudd_IsComplement(bFunc->next) )
return;
bFunc->next = Cudd_Regular(bFunc->next);
if ( cuddIsConstant(bFunc) )
return;
Abc_NodeSupportClear_rec( cuddT(bFunc) );
Abc_NodeSupportClear_rec( Cudd_Regular(cuddE(bFunc)) );
}
/**Function*************************************************************
Synopsis [Computes support of the node.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NodeSupport( DdNode * bFunc, Vec_Str_t * vSupport, int nVars )
{
int Counter, i;
// compute the support by marking the BDD
Vec_StrFill( vSupport, nVars, 0 );
Abc_NodeSupport_rec( bFunc, vSupport );
// clear the marak
Abc_NodeSupportClear_rec( bFunc );
// get the number of support variables
Counter = 0;
for ( i = 0; i < nVars; i++ )
Counter += vSupport->pArray[i];
return Counter;
}
/**Function*************************************************************
Synopsis [Find the number of unique variables after collapsing.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NodeCheckDupFanin( Abc_Obj_t * pFanin, Abc_Obj_t * pFanout, int * piFanin )
{
Abc_Obj_t * pObj;
int i, Counter = 0;
Abc_ObjForEachFanin( pFanout, pObj, i )
if ( pObj == pFanin )
{
if ( piFanin )
*piFanin = i;
Counter++;
}
return Counter;
}
/**Function*************************************************************
Synopsis [Find the number of unique variables after collapsing.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NodeCollapseSuppSize( Abc_Obj_t * pFanin, Abc_Obj_t * pFanout, Vec_Ptr_t * vFanins )
{
Abc_Obj_t * pObj;
int i;
Vec_PtrClear( vFanins );
Abc_ObjForEachFanin( pFanout, pObj, i )
if ( pObj != pFanin )
Vec_PtrPushUnique( vFanins, pObj );
Abc_ObjForEachFanin( pFanin, pObj, i )
Vec_PtrPushUnique( vFanins, pObj );
return Vec_PtrSize( vFanins );
}
/**Function*************************************************************
Synopsis [Returns the index of the new fanin.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_ObjFaninNumberNew( Vec_Ptr_t * vFanins, Abc_Obj_t * pFanin )
{
Abc_Obj_t * pObj;
int i;
Vec_PtrForEachEntry( Abc_Obj_t *, vFanins, pObj, i )
if ( pObj == pFanin )
return i;
return -1;
}
/**Function*************************************************************
Synopsis [Find the permutation map for the given node into the new order.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NodeCollapsePermMap( Abc_Obj_t * pNode, Abc_Obj_t * pSkip, Vec_Ptr_t * vFanins, int * pPerm )
{
Abc_Obj_t * pFanin;
int i;
for ( i = 0; i < Vec_PtrSize(vFanins); i++ )
pPerm[i] = i;
Abc_ObjForEachFanin( pNode, pFanin, i )
{
if ( pFanin == pSkip )
continue;
pPerm[i] = Abc_ObjFaninNumberNew( vFanins, pFanin );
if ( pPerm[i] == -1 )
return 0;
}
return 1;
}
/**Function*************************************************************
Synopsis [Computes support of the node.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
DdNode * Abc_NodeCollapseFunc( Abc_Obj_t * pFanin, Abc_Obj_t * pFanout, Vec_Ptr_t * vFanins, int * pPermFanin, int * pPermFanout )
{
DdManager * dd = (DdManager *)pFanin->pNtk->pManFunc;
DdNode * bVar, * bFunc0, * bFunc1, * bTemp, * bFanin, * bFanout;
int RetValue, nSize, iFanin;
// can only eliminate if fanin occurs in the fanin list of the fanout exactly once
if ( Abc_NodeCheckDupFanin( pFanin, pFanout, &iFanin ) != 1 )
return NULL;
// find the new number of fanins after collapsing
nSize = Abc_NodeCollapseSuppSize( pFanin, pFanout, vFanins );
bVar = Cudd_bddIthVar( dd, nSize - 1 );
assert( nSize <= dd->size );
// find the permutation after collapsing
RetValue = Abc_NodeCollapsePermMap( pFanin, NULL, vFanins, pPermFanin );
assert( RetValue );
RetValue = Abc_NodeCollapsePermMap( pFanout, pFanin, vFanins, pPermFanout );
assert( RetValue );
// cofactor the local function of the node
bVar = Cudd_bddIthVar( dd, iFanin );
bFunc0 = Cudd_Cofactor( dd, (DdNode *)pFanout->pData, Cudd_Not(bVar) ); Cudd_Ref( bFunc0 );
bFunc1 = Cudd_Cofactor( dd, (DdNode *)pFanout->pData, bVar ); Cudd_Ref( bFunc1 );
// find the permutation after collapsing
bFunc0 = Cudd_bddPermute( dd, bTemp = bFunc0, pPermFanout ); Cudd_Ref( bFunc0 );
Cudd_RecursiveDeref( dd, bTemp );
bFunc1 = Cudd_bddPermute( dd, bTemp = bFunc1, pPermFanout ); Cudd_Ref( bFunc1 );
Cudd_RecursiveDeref( dd, bTemp );
bFanin = Cudd_bddPermute( dd, (DdNode *)pFanin->pData, pPermFanin ); Cudd_Ref( bFanin );
// create the new function
bFanout = Cudd_bddIte( dd, bFanin, bFunc1, bFunc0 ); Cudd_Ref( bFanout );
Cudd_RecursiveDeref( dd, bFanin );
Cudd_RecursiveDeref( dd, bFunc1 );
Cudd_RecursiveDeref( dd, bFunc0 );
Cudd_Deref( bFanout );
return bFanout;
}
/**Function*************************************************************
Synopsis [Collapses one node into its fanout.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NodeCollapse( Abc_Obj_t * pFanin, Abc_Obj_t * pFanout, Vec_Ptr_t * vFanins, int * pPermFanin, int * pPermFanout )
{
Abc_Obj_t * pFanoutNew, * pObj;
DdNode * bFanoutNew;
int i;
assert( Abc_NtkIsBddLogic(pFanin->pNtk) );
assert( Abc_ObjIsNode(pFanin) );
assert( Abc_ObjIsNode(pFanout) );
bFanoutNew = Abc_NodeCollapseFunc( pFanin, pFanout, vFanins, pPermFanin, pPermFanout );
if ( bFanoutNew == NULL )
return 0;
Cudd_Ref( bFanoutNew );
// create the new node
pFanoutNew = Abc_NtkCreateNode( pFanin->pNtk );
Vec_PtrForEachEntry( Abc_Obj_t *, vFanins, pObj, i )
Abc_ObjAddFanin( pFanoutNew, pObj );
pFanoutNew->pData = bFanoutNew;
// minimize the node
Abc_NodeMinimumBase( pFanoutNew );
// transfer the fanout
Abc_ObjTransferFanout( pFanout, pFanoutNew );
assert( Abc_ObjFanoutNum( pFanout ) == 0 );
Abc_NtkDeleteObj_rec( pFanout, 1 );
return 1;
}
/**Function*************************************************************
Synopsis [Eliminates the nodes into their fanouts if the node size does not exceed this number.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NtkEliminate( Abc_Ntk_t * pNtk, int nMaxSize, int fReverse, int fVerbose )
{
extern void Abc_NtkBddReorder( Abc_Ntk_t * pNtk, int fVerbose );
Vec_Ptr_t * vFanouts, * vFanins, * vNodes;
Abc_Obj_t * pNode, * pFanout;
int * pPermFanin, * pPermFanout;
int RetValue, i, k;
assert( nMaxSize > 0 );
assert( Abc_NtkIsLogic(pNtk) );
// convert network to BDD representation
if ( !Abc_NtkToBdd(pNtk) )
{
fprintf( stdout, "Converting to BDD has failed.\n" );
return 0;
}
// prepare nodes for sweeping
Abc_NtkRemoveDupFanins( pNtk );
Abc_NtkMinimumBase( pNtk );
Abc_NtkCleanup( pNtk, 0 );
// get the nodes in the given order
vNodes = fReverse? Abc_NtkDfsReverse( pNtk ) : Abc_NtkDfs( pNtk, 0 );
// go through the nodes and decide is they can be eliminated
pPermFanin = ABC_ALLOC( int, nMaxSize + 100 );
pPermFanout = ABC_ALLOC( int, nMaxSize + 100 );
vFanins = Vec_PtrAlloc( 100 );
vFanouts = Vec_PtrAlloc( 100 );
Vec_PtrForEachEntry( Abc_Obj_t *, vNodes, pNode, i )
{
if ( Abc_NodeFindCoFanout(pNode) != NULL )
continue;
if ( Abc_ObjFaninNum(pNode) > nMaxSize )
continue;
Abc_ObjForEachFanout( pNode, pFanout, k )
if ( Abc_NodeCollapseSuppSize(pNode, pFanout, vFanins) > nMaxSize )
break;
if ( k < Abc_ObjFanoutNum(pNode) )
continue;
// perform elimination
Abc_NodeCollectFanouts( pNode, vFanouts );
Vec_PtrForEachEntry( Abc_Obj_t *, vFanouts, pFanout, k )
{
RetValue = Abc_NodeCollapse( pNode, pFanout, vFanins, pPermFanin, pPermFanout );
assert( RetValue );
}
}
Abc_NtkBddReorder( pNtk, 0 );
Vec_PtrFree( vFanins );
Vec_PtrFree( vFanouts );
Vec_PtrFree( vNodes );
ABC_FREE( pPermFanin );
ABC_FREE( pPermFanout );
return 1;
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
ABC_NAMESPACE_IMPL_END
|
