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yap-6.3/packages/cplint/cplint_Prob.c
2010-07-27 16:53:47 +02:00

210 lines
4.3 KiB
C

/*
LPAD and CP-Logic interpreter
Copyright (c) 2007, Fabrizio Riguzzi
This package uses the library cudd, see http://vlsi.colorado.edu/~fabio/CUDD/
for the relative license.
This file contains the definition of Prob and ProbBool plus the functions
for building the BDD
*/
#include "cplint.h"
#include <stdlib.h>
int correctPosition(int index,variable v, DdNode * node,int posBVar);
DdNode * retFunction(DdManager * mgr,expr expression, variables v)
/* given an expression term1+term2+...+termn, returns the BDD that implements that function */
{
term term1;
DdNode * tNode, * tmp, *tmp1;
int i;
i=0;
tNode=Cudd_ReadLogicZero(mgr);
Cudd_Ref(tNode);
while(i<expression.nTerms)
{
term1=expression.terms[i];
tmp=retTerm(mgr,term1,v);
Cudd_Ref(tmp);
tmp1=Cudd_bddOr(mgr,tNode,tmp);
Cudd_Ref(tmp1);
Cudd_RecursiveDeref(mgr,tNode);
tNode=tmp1;
i++;
}
return tNode;
}
DdNode * retTerm(DdManager * mgr,term t, variables v)
/* given a term V1=v1 and V2=v2 ... Vn=vn, returns the BDD that implements that function */
{
factor f;
DdNode * fNode, * tmp, *tmp1;
int i;
i=0;
fNode=Cudd_ReadOne(mgr);
Cudd_Ref(fNode);
while (i<t.nFact)
{
f=t.factors[i];
tmp=retFactor(mgr,f,v);
Cudd_Ref(tmp);
tmp1= Cudd_bddAnd(mgr,fNode,tmp);
Cudd_Ref(tmp1);
Cudd_RecursiveDeref(mgr,fNode);
fNode=tmp1;
i++;
}
return fNode;
}
DdNode * retFactor(DdManager * mgr, factor f, variables vars)
/* given a factor V=v, returns the BDD that implements that function */
{
int varIndex;
int value;
int i;
int bit;
variable v;
DdNode * node, *booleanVar, * tmp;
DdNode ** booleanVars;
varIndex=f.var;
value=f.value;
v=vars.varar[varIndex];
booleanVars=v.booleanVars;
i=v.nBit-1;
node=Cudd_ReadOne(mgr);
Cudd_Ref(node);
/* booelan var with index 0 in v.booleanVars is the most significant */
do {
booleanVar=booleanVars[i];
bit=value & 01;
if (bit)
{
tmp=Cudd_bddAnd(mgr,node,booleanVar);
Cudd_Ref(tmp);
}
else
{
tmp=Cudd_bddAnd(mgr,node,Cudd_Not(booleanVar));
Cudd_Ref(tmp);
}
value=value>>1;
i--;
Cudd_RecursiveDeref(mgr,node);
node=tmp;
} while (i>=0);
return node;
}
double Prob(DdNode *node, variables vars, GHashTable * nodes)
/* compute the probability of the expression rooted at node
nodes is used to store nodes for which the probability has alread been computed
so that it is not recomputed
*/
{
int index,mVarIndex,nBit;
variable v;
double res;
double value;
double * value_p;
DdNode **key;
double *rp;
index=node->index;
if (Cudd_IsConstant(node))
{
value=node->type.value;
return value;
}
else
{
value_p=g_hash_table_lookup(nodes,&node);
if (value_p!=NULL)
{
return *value_p;
}
else
{
mVarIndex=vars.bVar2mVar[index];
v=vars.varar[mVarIndex];
nBit=v.nBit;
res=ProbBool(node,0,nBit,0,v,vars,nodes);
key=(DdNode **)malloc(sizeof(DdNode *));
*key=node;
rp=(double *)malloc(sizeof(double));
*rp=res;
g_hash_table_insert(nodes, key, rp);
return res;
}
}
}
double ProbBool(DdNode *node, int bits, int nBit,int posBVar,variable v,
variables vars, GHashTable * nodes)
/* explores a group of binary variables making up the multivalued variable v */
{
DdNode *T,*F;
double p,res;
double * probs;
probs=v.probabilities;
if (nBit==0)
{
if (bits>=v.nVal)
return 0;
else
{
p=probs[bits];
res=p*Prob(node,vars,nodes);
return res;
}
}
else
{
if (correctPosition(node->index,v,node,posBVar))
{
T = node->type.kids.T;
F = node->type.kids.E;
bits=bits<<1;
res=ProbBool(T,bits+1,nBit-1,posBVar+1,v,vars,nodes)+
ProbBool(F,bits,nBit-1,posBVar+1,v,vars,nodes);
return res;
}
else
{
bits=bits<<1;
res=ProbBool(node,bits+1,nBit-1,posBVar+1,v,vars,nodes)+
ProbBool(node,bits,nBit-1,posBVar+1,v,vars,nodes);
return res;
}
}
}
int correctPosition(int index,variable v, DdNode * node,int posBVar)
/* returns 1 is the boolean variable with index posBVar is in the correct position
currently explored by ProbBool */
{
DdNode * bvar;
bvar=v.booleanVars[posBVar];
return bvar->index==index;
}