src/bdd/cudd/cuddLiteral.c

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#include "util_hack.h"
#include "cuddInt.h"


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/* Constant declarations                                                     */
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/* Stucture declarations                                                     */
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/* Type declarations                                                         */
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/* Variable declarations                                                     */
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#ifndef lint
static char rcsid[] DD_UNUSED = "$Id: cuddLiteral.c,v 1.1.1.1 2003/02/24 22:23:52 wjiang Exp $";
#endif

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/* Macro declarations                                                        */
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/* Static function prototypes                                                */
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/* Definition of exported functions                                          */
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DdNode *
Cudd_bddLiteralSetIntersection(
  DdManager * dd,
  DdNode * f,
  DdNode * g)
{
    DdNode *res;

    do {
        dd->reordered = 0;
        res = cuddBddLiteralSetIntersectionRecur(dd,f,g);
    } while (dd->reordered == 1);
    return(res);

} /* end of Cudd_bddLiteralSetIntersection */


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/* Definition of internal functions                                          */
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DdNode *
cuddBddLiteralSetIntersectionRecur(
  DdManager * dd,
  DdNode * f,
  DdNode * g)
{
    DdNode *res, *tmp;
    DdNode *F, *G;
    DdNode *fc, *gc;
    DdNode *one;
    DdNode *zero;
    unsigned int topf, topg, comple;
    int phasef, phaseg;

    statLine(dd);
    if (f == g) return(f);

    F = Cudd_Regular(f);
    G = Cudd_Regular(g);
    one = DD_ONE(dd);

    /* Here f != g. If F == G, then f and g are complementary.
    ** Since they are two cubes, this case only occurs when f == v,
    ** g == v', and v is a variable or its complement.
    */
    if (F == G) return(one);

    zero = Cudd_Not(one);
    topf = cuddI(dd,F->index);
    topg = cuddI(dd,G->index);
    /* Look for a variable common to both cubes. If there are none, this
    ** loop will stop when the constant node is reached in both cubes.
    */
    while (topf != topg) {
        if (topf < topg) {      /* move down on f */
            comple = f != F;
            f = cuddT(F);
            if (comple) f = Cudd_Not(f);
            if (f == zero) {
                f = cuddE(F);
                if (comple) f = Cudd_Not(f);
            }
            F = Cudd_Regular(f);
            topf = cuddI(dd,F->index);
        } else if (topg < topf) {
            comple = g != G;
            g = cuddT(G);
            if (comple) g = Cudd_Not(g);
            if (g == zero) {
                g = cuddE(G);
                if (comple) g = Cudd_Not(g);
            }
            G = Cudd_Regular(g);
            topg = cuddI(dd,G->index);
        }
    }

    /* At this point, f == one <=> g == 1. It suffices to test one of them. */
    if (f == one) return(one);

    res = cuddCacheLookup2(dd,Cudd_bddLiteralSetIntersection,f,g);
    if (res != NULL) {
        return(res);
    }

    /* Here f and g are both non constant and have the same top variable. */
    comple = f != F;
    fc = cuddT(F);
    phasef = 1;
    if (comple) fc = Cudd_Not(fc);
    if (fc == zero) {
        fc = cuddE(F);
        phasef = 0;
        if (comple) fc = Cudd_Not(fc);
    }
    comple = g != G;
    gc = cuddT(G);
    phaseg = 1;
    if (comple) gc = Cudd_Not(gc);
    if (gc == zero) {
        gc = cuddE(G);
        phaseg = 0;
        if (comple) gc = Cudd_Not(gc);
    }

    tmp = cuddBddLiteralSetIntersectionRecur(dd,fc,gc);
    if (tmp == NULL) {
        return(NULL);
    }

    if (phasef != phaseg) {
        res = tmp;
    } else {
        cuddRef(tmp);
        if (phasef == 0) {
            res = cuddBddAndRecur(dd,Cudd_Not(dd->vars[F->index]),tmp);
        } else {
            res = cuddBddAndRecur(dd,dd->vars[F->index],tmp);
        }
        if (res == NULL) {
            Cudd_RecursiveDeref(dd,tmp);
            return(NULL);
        }
        cuddDeref(tmp); /* Just cuddDeref, because it is included in result */
    }

    cuddCacheInsert2(dd,Cudd_bddLiteralSetIntersection,f,g,res);

    return(res);

} /* end of cuddBddLiteralSetIntersectionRecur */


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/* Definition of static functions                                            */
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