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[buddy] Add a function bdd_implies to decide implications between BDDs.

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* src/bdd.h (bdd_implies): New function.
* src/bddop.c (bdd_implies): Implement it.
(CACHEID_IMPLIES, IMPLIES_HASH): New helper macros.
This commit is contained in:
Alexandre Duret-Lutz 2012-06-13 17:56:37 +02:00
parent e7a46e10e2
commit a814b97543
3 changed files with 69 additions and 0 deletions
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56
buddy/src/bddop.c
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@ -51,6 +51,7 @@
#define CACHEID_PATHCOU 0x4
#define CACHEID_SETXOR 0x5
#define CACHEID_SUPPORT 0x6
#define CACHEID_IMPLIES 0x7
/* Hash value modifiers for replace/compose */
#define CACHEID_REPLACE 0x0
@ -159,6 +160,7 @@ static int varset2svartable(BDD);
#define APPLYHASH(l,r,op) (TRIPLE(l,r,op))
#define ITEHASH(f,g,h) (TRIPLE(f,g,h))
#define SETXORHASH(l,r) (TRIPLE(l,r,CACHEID_SETXOR))
#define IMPLIESHASH(l,r) (TRIPLE(l,r,CACHEID_IMPLIES))
#define RESTRHASH(r,var) (PAIR(r,var))
#define CONSTRAINHASH(f,c) (PAIR(f,c))
#define QUANTHASH(r) (r)
@ -894,6 +896,60 @@ BDD bdd_setxor(BDD l, BDD r)
}
/*=== bdd_implies =========================================================*/
/*
NAME {* bdd\_implies *}
SECTION {* operator *}
SHORT {* check whether one BDD implies another *}
PROTO {* int bdd_setxor(BDD l, BDD r) *}
DESCR {* Check wether $l$ implies $r$, or whether $r$ contains $l$. *}
RETURN {* 1 if $l$ implies $r$, 0 otherwise *}
*/
int bdd_implies(BDD l, BDD r)
{
BddCacheData *entry;
int res;
if ((l == r) || ISZERO(l) || ISONE(r))
return 1;
if (ISONE(l) || ISZERO(r))
return 0;
entry = BddCache_lookup(&misccache, IMPLIESHASH(l,r));
if (entry->a == l && entry->b == r && entry->c == CACHEID_IMPLIES)
{
#ifdef CACHESTATS
bddcachestats.opHit++;
#endif
return entry->r.res;
}
#ifdef CACHESTATS
bddcachestats.opMiss++;
#endif
if (LEVEL(l) == LEVEL(r))
{
res = bdd_implies(LOW(l), LOW(r)) && bdd_implies(HIGH(l), HIGH(r));
}
else if (LEVEL(l) < LEVEL(r))
{
res = bdd_implies(LOW(l), r) && bdd_implies(HIGH(l), r);
}
else /* LEVEL(l) > LEVEL(r) */
{
res = bdd_implies(l, LOW(r)) && bdd_implies(l, HIGH(r));
}
entry->a = l;
entry->b = r;
entry->c = CACHEID_IMPLIES;
entry->r.res = res;
return res;
}
/*=== ITE ==============================================================*/