/**CFile*********************************************************************** FileName [cuddRef.c] PackageName [cudd] Synopsis [Functions that manipulate the reference counts.] Description [External procedures included in this module: Internal procedures included in this module: ] SeeAlso [] Author [Fabio Somenzi] Copyright [ This file was created at the University of Colorado at Boulder. The University of Colorado at Boulder makes no warranty about the suitability of this software for any purpose. It is presented on an AS IS basis.] ******************************************************************************/ #include "util_hack.h" #include "cuddInt.h" /*---------------------------------------------------------------------------*/ /* Constant declarations */ /*---------------------------------------------------------------------------*/ /*---------------------------------------------------------------------------*/ /* Stucture declarations */ /*---------------------------------------------------------------------------*/ /*---------------------------------------------------------------------------*/ /* Type declarations */ /*---------------------------------------------------------------------------*/ /*---------------------------------------------------------------------------*/ /* Variable declarations */ /*---------------------------------------------------------------------------*/ #ifndef lint static char rcsid[] DD_UNUSED = "$Id: cuddRef.c,v 1.1.1.1 2003/02/24 22:23:53 wjiang Exp $"; #endif /*---------------------------------------------------------------------------*/ /* Macro declarations */ /*---------------------------------------------------------------------------*/ /**AutomaticStart*************************************************************/ /*---------------------------------------------------------------------------*/ /* Static function prototypes */ /*---------------------------------------------------------------------------*/ /**AutomaticEnd***************************************************************/ /*---------------------------------------------------------------------------*/ /* Definition of exported functions */ /*---------------------------------------------------------------------------*/ /**Function******************************************************************** Synopsis [Increases the reference count of a node, if it is not saturated.] Description [] SideEffects [None] SeeAlso [Cudd_RecursiveDeref Cudd_Deref] ******************************************************************************/ void Cudd_Ref( DdNode * n) { n = Cudd_Regular(n); cuddSatInc(n->ref); } /* end of Cudd_Ref */ /**Function******************************************************************** Synopsis [Decreases the reference count of node n.] Description [Decreases the reference count of node n. If n dies, recursively decreases the reference counts of its children. It is used to dispose of a DD that is no longer needed.] SideEffects [None] SeeAlso [Cudd_Deref Cudd_Ref Cudd_RecursiveDerefZdd] ******************************************************************************/ void Cudd_RecursiveDeref( DdManager * table, DdNode * n) { DdNode *N; int ord; DdNodePtr *stack = table->stack; int SP = 1; unsigned int live = table->keys - table->dead; if (live > table->peakLiveNodes) { table->peakLiveNodes = live; } N = Cudd_Regular(n); do { #ifdef DD_DEBUG assert(N->ref != 0); #endif if (N->ref == 1) { N->ref = 0; table->dead++; #ifdef DD_STATS table->nodesDropped++; #endif if (cuddIsConstant(N)) { table->constants.dead++; N = stack[--SP]; } else { ord = table->perm[N->index]; stack[SP++] = Cudd_Regular(cuddE(N)); table->subtables[ord].dead++; N = cuddT(N); } } else { cuddSatDec(N->ref); N = stack[--SP]; } } while (SP != 0); } /* end of Cudd_RecursiveDeref */ /**Function******************************************************************** Synopsis [Decreases the reference count of BDD node n.] Description [Decreases the reference count of node n. If n dies, recursively decreases the reference counts of its children. It is used to dispose of a BDD that is no longer needed. It is more efficient than Cudd_RecursiveDeref, but it cannot be used on ADDs. The greater efficiency comes from being able to assume that no constant node will ever die as a result of a call to this procedure.] SideEffects [None] SeeAlso [Cudd_RecursiveDeref Cudd_DelayedDerefBdd] ******************************************************************************/ void Cudd_IterDerefBdd( DdManager * table, DdNode * n) { DdNode *N; int ord; DdNodePtr *stack = table->stack; int SP = 1; unsigned int live = table->keys - table->dead; if (live > table->peakLiveNodes) { table->peakLiveNodes = live; } N = Cudd_Regular(n); do { #ifdef DD_DEBUG assert(N->ref != 0); #endif if (N->ref == 1) { N->ref = 0; table->dead++; #ifdef DD_STATS table->nodesDropped++; #endif ord = table->perm[N->index]; stack[SP++] = Cudd_Regular(cuddE(N)); table->subtables[ord].dead++; N = cuddT(N); } else { cuddSatDec(N->ref); N = stack[--SP]; } } while (SP != 0); } /* end of Cudd_IterDerefBdd */ /**Function******************************************************************** Synopsis [Decreases the reference count of BDD node n.] Description [Enqueues node n for later dereferencing. If the queue is full decreases the reference count of the oldest node N to make room for n. If N dies, recursively decreases the reference counts of its children. It is used to dispose of a BDD that is currently not needed, but may be useful again in the near future. The dereferencing proper is done as in Cudd_IterDerefBdd.] SideEffects [None] SeeAlso [Cudd_RecursiveDeref Cudd_IterDerefBdd] ******************************************************************************/ void Cudd_DelayedDerefBdd( DdManager * table, DdNode * n) { DdNode *N; int ord; DdNodePtr *stack; int SP; unsigned int live = table->keys - table->dead; if (live > table->peakLiveNodes) { table->peakLiveNodes = live; } n = Cudd_Regular(n); #ifdef DD_DEBUG assert(n->ref != 0); #endif #ifdef DD_NO_DEATH_ROW N = n; #else if (cuddIsConstant(n) || n->ref > 1) { #ifdef DD_DEBUG assert(n->ref != 1 && (!cuddIsConstant(n) || n == DD_ONE(table))); #endif cuddSatDec(n->ref); return; } N = table->deathRow[table->nextDead]; if (N != NULL) { #endif #ifdef DD_DEBUG assert(!Cudd_IsComplement(N)); #endif stack = table->stack; SP = 1; do { #ifdef DD_DEBUG assert(N->ref != 0); #endif if (N->ref == 1) { N->ref = 0; table->dead++; #ifdef DD_STATS table->nodesDropped++; #endif ord = table->perm[N->index]; stack[SP++] = Cudd_Regular(cuddE(N)); table->subtables[ord].dead++; N = cuddT(N); } else { cuddSatDec(N->ref); N = stack[--SP]; } } while (SP != 0); #ifndef DD_NO_DEATH_ROW } table->deathRow[table->nextDead] = n; /* Udate insertion point. */ table->nextDead++; table->nextDead &= table->deadMask; #if 0 if (table->nextDead == table->deathRowDepth) { if (table->deathRowDepth < table->looseUpTo / 2) { extern void (*MMoutOfMemory)(long); void (*saveHandler)(long) = MMoutOfMemory; DdNodePtr *newRow; MMoutOfMemory = Cudd_OutOfMem; newRow = REALLOC(DdNodePtr,table->deathRow,2*table->deathRowDepth); MMoutOfMemory = saveHandler; if (newRow == NULL) { table->nextDead = 0; } else { int i; table->memused += table->deathRowDepth; i = table->deathRowDepth; table->deathRowDepth <<= 1; for (; i < table->deathRowDepth; i++) { newRow[i] = NULL; } table->deadMask = table->deathRowDepth - 1; table->deathRow = newRow; } } else { table->nextDead = 0; } } #endif #endif } /* end of Cudd_DelayedDerefBdd */ /**Function******************************************************************** Synopsis [Decreases the reference count of ZDD node n.] Description [Decreases the reference count of ZDD node n. If n dies, recursively decreases the reference counts of its children. It is used to dispose of a ZDD that is no longer needed.] SideEffects [None] SeeAlso [Cudd_Deref Cudd_Ref Cudd_RecursiveDeref] ******************************************************************************/ void Cudd_RecursiveDerefZdd( DdManager * table, DdNode * n) { DdNode *N; int ord; DdNodePtr *stack = table->stack; int SP = 1; N = n; do { #ifdef DD_DEBUG assert(N->ref != 0); #endif cuddSatDec(N->ref); if (N->ref == 0) { table->deadZ++; #ifdef DD_STATS table->nodesDropped++; #endif #ifdef DD_DEBUG assert(!cuddIsConstant(N)); #endif ord = table->permZ[N->index]; stack[SP++] = cuddE(N); table->subtableZ[ord].dead++; N = cuddT(N); } else { N = stack[--SP]; } } while (SP != 0); } /* end of Cudd_RecursiveDerefZdd */ /**Function******************************************************************** Synopsis [Decreases the reference count of node.] Description [Decreases the reference count of node. It is primarily used in recursive procedures to decrease the ref count of a result node before returning it. This accomplishes the goal of removing the protection applied by a previous Cudd_Ref.] SideEffects [None] SeeAlso [Cudd_RecursiveDeref Cudd_RecursiveDerefZdd Cudd_Ref] ******************************************************************************/ void Cudd_Deref( DdNode * node) { node = Cudd_Regular(node); cuddSatDec(node->ref); } /* end of Cudd_Deref */ /**Function******************************************************************** Synopsis [Checks the unique table for nodes with non-zero reference counts.] Description [Checks the unique table for nodes with non-zero reference counts. It is normally called before Cudd_Quit to make sure that there are no memory leaks due to missing Cudd_RecursiveDeref's. Takes into account that reference counts may saturate and that the basic constants and the projection functions are referenced by the manager. Returns the number of nodes with non-zero reference count. (Except for the cases mentioned above.)] SideEffects [None] SeeAlso [] ******************************************************************************/ int Cudd_CheckZeroRef( DdManager * manager) { int size; int i, j; int remain; /* the expected number of remaining references to one */ DdNodePtr *nodelist; DdNode *node; DdNode *sentinel = &(manager->sentinel); DdSubtable *subtable; int count = 0; int index; #ifndef DD_NO_DEATH_ROW cuddClearDeathRow(manager); #endif /* First look at the BDD/ADD subtables. */ remain = 1; /* reference from the manager */ size = manager->size; remain += 2 * size; /* reference from the BDD projection functions */ for (i = 0; i < size; i++) { subtable = &(manager->subtables[i]); nodelist = subtable->nodelist; for (j = 0; (unsigned) j < subtable->slots; j++) { node = nodelist[j]; while (node != sentinel) { if (node->ref != 0 && node->ref != DD_MAXREF) { index = (int) node->index; if (node != manager->vars[index]) { count++; } else { if (node->ref != 1) { count++; } } } node = node->next; } } } /* Then look at the ZDD subtables. */ size = manager->sizeZ; if (size) /* references from ZDD universe */ remain += 2; for (i = 0; i < size; i++) { subtable = &(manager->subtableZ[i]); nodelist = subtable->nodelist; for (j = 0; (unsigned) j < subtable->slots; j++) { node = nodelist[j]; while (node != NULL) { if (node->ref != 0 && node->ref != DD_MAXREF) { index = (int) node->index; if (node == manager->univ[manager->permZ[index]]) { if (node->ref > 2) { count++; } } else { count++; } } node = node->next; } } } /* Now examine the constant table. Plusinfinity, minusinfinity, and ** zero are referenced by the manager. One is referenced by the ** manager, by the ZDD universe, and by all projection functions. ** All other nodes should have no references. */ nodelist = manager->constants.nodelist; for (j = 0; (unsigned) j < manager->constants.slots; j++) { node = nodelist[j]; while (node != NULL) { if (node->ref != 0 && node->ref != DD_MAXREF) { if (node == manager->one) { if ((int) node->ref != remain) { count++; } } else if (node == manager->zero || node == manager->plusinfinity || node == manager->minusinfinity) { if (node->ref != 1) { count++; } } else { count++; } } node = node->next; } } return(count); } /* end of Cudd_CheckZeroRef */ /*---------------------------------------------------------------------------*/ /* Definition of internal functions */ /*---------------------------------------------------------------------------*/ /**Function******************************************************************** Synopsis [Brings children of a dead node back.] Description [] SideEffects [None] SeeAlso [cuddReclaimZdd] ******************************************************************************/ void cuddReclaim( DdManager * table, DdNode * n) { DdNode *N; int ord; DdNodePtr *stack = table->stack; int SP = 1; double initialDead = table->dead; N = Cudd_Regular(n); #ifdef DD_DEBUG assert(N->ref == 0); #endif do { if (N->ref == 0) { N->ref = 1; table->dead--; if (cuddIsConstant(N)) { table->constants.dead--; N = stack[--SP]; } else { ord = table->perm[N->index]; stack[SP++] = Cudd_Regular(cuddE(N)); table->subtables[ord].dead--; N = cuddT(N); } } else { cuddSatInc(N->ref); N = stack[--SP]; } } while (SP != 0); N = Cudd_Regular(n); cuddSatDec(N->ref); table->reclaimed += initialDead - table->dead; } /* end of cuddReclaim */ /**Function******************************************************************** Synopsis [Brings children of a dead ZDD node back.] Description [] SideEffects [None] SeeAlso [cuddReclaim] ******************************************************************************/ void cuddReclaimZdd( DdManager * table, DdNode * n) { DdNode *N; int ord; DdNodePtr *stack = table->stack; int SP = 1; N = n; #ifdef DD_DEBUG assert(N->ref == 0); #endif do { cuddSatInc(N->ref); if (N->ref == 1) { table->deadZ--; table->reclaimed++; #ifdef DD_DEBUG assert(!cuddIsConstant(N)); #endif ord = table->permZ[N->index]; stack[SP++] = cuddE(N); table->subtableZ[ord].dead--; N = cuddT(N); } else { N = stack[--SP]; } } while (SP != 0); cuddSatDec(n->ref); } /* end of cuddReclaimZdd */ /**Function******************************************************************** Synopsis [Shrinks the death row.] Description [Shrinks the death row by a factor of four.] SideEffects [None] SeeAlso [cuddClearDeathRow] ******************************************************************************/ void cuddShrinkDeathRow( DdManager *table) { #ifndef DD_NO_DEATH_ROW int i; if (table->deathRowDepth > 3) { for (i = table->deathRowDepth/4; i < table->deathRowDepth; i++) { if (table->deathRow[i] == NULL) break; Cudd_IterDerefBdd(table,table->deathRow[i]); table->deathRow[i] = NULL; } table->deathRowDepth /= 4; table->deadMask = table->deathRowDepth - 2; if ((unsigned) table->nextDead > table->deadMask) { table->nextDead = 0; } table->deathRow = REALLOC(DdNodePtr, table->deathRow, table->deathRowDepth); } #endif } /* end of cuddShrinkDeathRow */ /**Function******************************************************************** Synopsis [Clears the death row.] Description [] SideEffects [None] SeeAlso [Cudd_DelayedDerefBdd Cudd_IterDerefBdd Cudd_CheckZeroRef cuddGarbageCollect] ******************************************************************************/ void cuddClearDeathRow( DdManager *table) { #ifndef DD_NO_DEATH_ROW int i; for (i = 0; i < table->deathRowDepth; i++) { if (table->deathRow[i] == NULL) break; Cudd_IterDerefBdd(table,table->deathRow[i]); table->deathRow[i] = NULL; } #ifdef DD_DEBUG for (; i < table->deathRowDepth; i++) { assert(table->deathRow[i] == NULL); } #endif table->nextDead = 0; #endif } /* end of cuddClearDeathRow */ /**Function******************************************************************** Synopsis [Checks whether a node is in the death row.] Description [Checks whether a node is in the death row. Returns the position of the first occurrence if the node is present; -1 otherwise.] SideEffects [None] SeeAlso [Cudd_DelayedDerefBdd cuddClearDeathRow] ******************************************************************************/ int cuddIsInDeathRow( DdManager *dd, DdNode *f) { #ifndef DD_NO_DEATH_ROW int i; for (i = 0; i < dd->deathRowDepth; i++) { if (f == dd->deathRow[i]) { return(i); } } #endif return(-1); } /* end of cuddIsInDeathRow */ /**Function******************************************************************** Synopsis [Counts how many times a node is in the death row.] Description [] SideEffects [None] SeeAlso [Cudd_DelayedDerefBdd cuddClearDeathRow cuddIsInDeathRow] ******************************************************************************/ int cuddTimesInDeathRow( DdManager *dd, DdNode *f) { int count = 0; #ifndef DD_NO_DEATH_ROW int i; for (i = 0; i < dd->deathRowDepth; i++) { count += f == dd->deathRow[i]; } #endif return(count); } /* end of cuddTimesInDeathRow */ /*---------------------------------------------------------------------------*/ /* Definition of static functions */ /*---------------------------------------------------------------------------*/