void solver_reducedb(solver* s)
{
int i, j;
double extra_lim = s->cla_inc / vecp_size(&s->learnts);
/* Remove any clause below this activity */
clause** learnts = (clause**)vecp_begin(&s->learnts);
clause** reasons = s->reasons;
sort(vecp_begin(&s->learnts), vecp_size(&s->learnts), clause_cmp);
for (i = j = 0; i < vecp_size(&s->learnts) / 2; i++){
if (clause_size(learnts[i]) > 2
&& reasons[lit_var(*clause_begin(learnts[i]))]
!= learnts[i])
clause_remove(s,learnts[i]);
else
learnts[j++] = learnts[i];
}
for (; i < vecp_size(&s->learnts); i++){
if (clause_size(learnts[i]) > 2
&& reasons[lit_var(*clause_begin(learnts[i]))]
!= learnts[i]
&& clause_activity(learnts[i]) < extra_lim)
clause_remove(s,learnts[i]);
else
learnts[j++] = learnts[i];
}
/* printf("reducedb deleted %d\n", vecp_size(&s->learnts) - j); */
vecp_resize(&s->learnts,j);
}
static inline void vecp_remove(vecp* v, void* e)
{
void** ws = vecp_begin(v);
int j = 0;
for (; ws[j] != e ; j++);
assert(j < vecp_size(v));
for (; j < vecp_size(v)-1; j++) ws[j] = ws[j+1];
vecp_resize(v,vecp_size(v)-1);
}
static inline void act_clause_rescale(solver* s) {
clause** cs = (clause**)vecp_begin(&s->learnts);
int i;
for (i = 0; i < vecp_size(&s->learnts); i++){
float a = clause_activity(cs[i]);
clause_setactivity(cs[i], a * (float)1e-20);
}
s->cla_inc *= (float)1e-20;
}
void printclauses(solver* s)
{
int i;
clause* c;
printf("Printing clauses:\n");
for(i = 0; i < vecp_size(&s->clauses); i++){
c = vecp_begin(&s->clauses)[i];
printf("Clause %d:\t\t",i);
printvalues(c->lits,c->lits + c->size);
printf("\t\tsize: %d\tlevel_sat: %d\n",c->size,c->level_sat);
}
}
void solver_delete(solver* s)
{
int i;
for (i = 0; i < vecp_size(&s->clauses); i++)
free(vecp_begin(&s->clauses)[i]);
for (i = 0; i < vecp_size(&s->learnts); i++)
free(vecp_begin(&s->learnts)[i]);
/* delete vectors */
vecp_delete(&s->clauses);
vecp_delete(&s->learnts);
veci_delete(&s->order);
veci_delete(&s->trail_lim);
veci_delete(&s->tagged);
veci_delete(&s->stack);
veci_delete(&s->model);
free(s->binary);
/* delete arrays */
if (s->wlists != 0){
int i;
for (i = 0; i < s->size*2; i++)
vecp_delete(&s->wlists[i]);
/* if one is different from null, all are */
free(s->wlists);
free(s->activity );
free(s->assigns );
free(s->orderpos );
free(s->reasons );
free(s->levels );
free(s->trail );
free(s->tags );
}
free(s);
}
// returns the level_choice of the level backtracked to
lit backtrack_once(solver* s){
int i;
clause* c;
for(i = 0; i < s->size*2; i++){
if(s->levels[i] == s->cur_level){
s->assigns[i] = l_Undef;
s->assigns[lit_neg(i)] = l_Undef;
s->levels[i] = -1;
}
}
for(i = s->tail; i < vecp_size(&s->clauses); i++){
c = vecp_begin(&s->clauses)[i];
if(c->level_sat == s->cur_level){
c->level_sat = -1;
s->tail++;
}
else break;
}
return s->level_choice[s->cur_level--];
}
void solver_delete(solver* s)
{
int i;
for (i = 0; i < vecp_size(&s->clauses); i++) // free all clauses
free(vecp_begin(&s->clauses)[i]);
// delete vectors
vecp_delete(&s->clauses);
// delete arrays
if (s->decisions != 0){
// if one is different from null, all are
free(s->decisions);
free(s->level_choice);
free(s->assigns );
free(s->levels );
free(s->counts );
}
free(s);
}
bool solver_simplify(solver* s)
{
clause** reasons;
int type;
assert(solver_dlevel(s) == 0);
if (solver_propagate(s) != 0)
return false;
if (s->qhead == s->simpdb_assigns || s->simpdb_props > 0)
return true;
reasons = s->reasons;
for (type = 0; type < 2; type++){
vecp* cs = type ? &s->learnts : &s->clauses;
clause** cls = (clause**)vecp_begin(cs);
int i, j;
for (j = i = 0; i < vecp_size(cs); i++){
if (reasons[lit_var(*clause_begin(cls[i]))] != cls[i] &&
clause_simplify(s,cls[i]) == l_True)
clause_remove(s,cls[i]);
else
cls[j++] = cls[i];
}
vecp_resize(cs,j);
}
s->simpdb_assigns = s->qhead;
/* (shouldn't depend on 'stats' really, but it will do for now) */
s->simpdb_props = (int)(s->stats.clauses_literals
+ s->stats.learnts_literals);
return true;
}
static lbool solver_search(solver* s, int nof_conflicts,
int nof_learnts)
{
int* levels = s->levels;
double var_decay = 0.95;
double clause_decay = 0.999;
double random_var_freq = 0.02;
int conflictC = 0;
veci learnt_clause;
assert(s->root_level == solver_dlevel(s));
s->stats.starts++;
s->var_decay = (float)(1 / var_decay );
s->cla_decay = (float)(1 / clause_decay);
veci_resize(&s->model,0);
veci_new(&learnt_clause);
for (;;){
clause* confl = solver_propagate(s);
if (confl != 0){
/* CONFLICT */
int blevel;
#ifdef VERBOSEDEBUG
printf(L_IND"**CONFLICT**\n", L_ind);
#endif
s->stats.conflicts++; conflictC++;
if (solver_dlevel(s) == s->root_level){
veci_delete(&learnt_clause);
return l_False;
}
veci_resize(&learnt_clause,0);
solver_analyze(s, confl, &learnt_clause);
blevel = veci_size(&learnt_clause) > 1
? levels[lit_var(veci_begin(&learnt_clause)[1])]
: s->root_level;
blevel = s->root_level > blevel ? s->root_level : blevel;
solver_canceluntil(s,blevel);
solver_record(s,&learnt_clause);
act_var_decay(s);
act_clause_decay(s);
}else{
/* NO CONFLICT */
int next;
if (nof_conflicts >= 0 && conflictC >= nof_conflicts){
/* Reached bound on number of conflicts: */
s->progress_estimate = solver_progress(s);
solver_canceluntil(s,s->root_level);
veci_delete(&learnt_clause);
return l_Undef; }
if (solver_dlevel(s) == 0)
/* Simplify the set of problem clauses: */
solver_simplify(s);
if (nof_learnts >= 0
&& vecp_size(&s->learnts) - s->qtail >= nof_learnts)
/* Reduce the set of learnt clauses: */
solver_reducedb(s);
/* New variable decision: */
s->stats.decisions++;
next = order_select(s,(float)random_var_freq);
if (next == var_Undef){
/* Model found: */
lbool* values = s->assigns;
int i;
for (i = 0; i < s->size; i++)
veci_push(&s->model,(int)values[i]);
solver_canceluntil(s,s->root_level);
veci_delete(&learnt_clause);
/*
veci apa; veci_new(&apa);
for (i = 0; i < s->size; i++)
veci_push(&apa,(int)(s->model.ptr[i] == l_True
? toLit(i) : lit_neg(toLit(i))));
printf("model: ");
printlits((lit*)apa.ptr,
(lit*)apa.ptr + veci_size(&apa)); printf("\n");
veci_delete(&apa);
*/
return l_True;
}
assume(s,lit_neg(toLit(next)));
}
}
#if 0 /* by mao; unreachable code */
return l_Undef; /* cannot happen */
#endif
}
clause* solver_propagate(solver* s)
{
lbool* values = s->assigns;
clause* confl = (clause*)0;
lit* lits;
/* printf("solver_propagate\n"); */
while (confl == 0 && s->qtail - s->qhead > 0){
lit p = s->trail[s->qhead++];
vecp* ws = solver_read_wlist(s,p);
clause **begin = (clause**)vecp_begin(ws);
clause **end = begin + vecp_size(ws);
clause **i, **j;
s->stats.propagations++;
s->simpdb_props--;
/* printf("checking lit %d: "L_LIT"\n", veci_size(ws),
L_lit(p)); */
for (i = j = begin; i < end; ){
if (clause_is_lit(*i)){
*j++ = *i;
if (!enqueue(s,clause_read_lit(*i),clause_from_lit(p))){
confl = s->binary;
(clause_begin(confl))[1] = lit_neg(p);
(clause_begin(confl))[0] = clause_read_lit(*i++);
/* Copy the remaining watches: */
while (i < end)
*j++ = *i++;
}
}else{
lit false_lit;
lbool sig;
lits = clause_begin(*i);
/* Make sure the false literal is data[1]: */
false_lit = lit_neg(p);
if (lits[0] == false_lit){
lits[0] = lits[1];
lits[1] = false_lit;
}
assert(lits[1] == false_lit);
/* printf("checking clause: ");
printlits(lits, lits+clause_size(*i));
printf("\n"); */
/* If 0th watch is true, then clause is already
satisfied. */
sig = !lit_sign(lits[0]); sig += sig - 1;
if (values[lit_var(lits[0])] == sig){
*j++ = *i;
}else{
/* Look for new watch: */
lit* stop = lits + clause_size(*i);
lit* k;
for (k = lits + 2; k < stop; k++){
lbool sig = lit_sign(*k); sig += sig - 1;
if (values[lit_var(*k)] != sig){
lits[1] = *k;
*k = false_lit;
vecp_push(solver_read_wlist(s,
lit_neg(lits[1])),*i);
goto next; }
}
*j++ = *i;
/* Clause is unit under assignment: */
if (!enqueue(s,lits[0], *i)){
confl = *i++;
/* Copy the remaining watches: */
while (i < end)
*j++ = *i++;
}
}
}
next:
i++;
}
s->stats.inspects += j - (clause**)vecp_begin(ws);
vecp_resize(ws,j - (clause**)vecp_begin(ws));
}
return confl;
}
int solver_nclauses(solver* s)
{
return vecp_size(&s->clauses);
}