zchaff_dbase.cpp

这是一种很好的SAT解析器。通过它

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#include "zchaff_dbase.h"

CDatabase::CDatabase()  
{ 	
    _stats.mem_used_up_counts 	= 0;
    _stats.mem_used_up 		= false;

    _stats.init_num_clauses 	= 0;
    _stats.init_num_literals 	= 0;
    _stats.num_added_clauses 	= 0;
    _stats.num_added_literals 	= 0;
    _stats.num_deleted_clauses 	= 0;
    _stats.num_del_orig_cls 	= 0;
    _stats.num_deleted_literals = 0;
    _stats.num_enlarge		= 0;
    _stats.num_compact		= 0;
    _lit_pool_start = (CLitPoolElement *) malloc (sizeof(CLitPoolElement) * STARTUP_LIT_POOL_SIZE); 
    _lit_pool_finish = _lit_pool_start;
    _lit_pool_end_storage = _lit_pool_start + STARTUP_LIT_POOL_SIZE;
    lit_pool_push_back(0); //set the first element as a spacing element

    _params.mem_limit = 1024*1024*1024; //that's 1 G

    variables().resize(1);	//var_id == 0 is never used.
    _allocated_gid    		= 0;
}

CDatabase::~CDatabase()
{ 
    free (_lit_pool_start); 
}

unsigned CDatabase::estimate_mem_usage (void)
{
    unsigned mem_lit_pool = sizeof(CLitPoolElement) * (lit_pool_size() + lit_pool_free_space());

    unsigned mem_vars = sizeof(CVariable) * variables().capacity();

    unsigned mem_cls = sizeof(CClause) * clauses().capacity();

    unsigned mem_cls_queue = sizeof(int) * _unused_clause_idx.size();

    unsigned mem_watched = 2 * num_clauses() *	sizeof(CLitPoolElement *);

    unsigned mem_lit_clauses = 0;
#ifdef KEEP_LIT_CLAUSES
    mem_lit_clauses = num_literals() * sizeof(ClauseIdx);
#endif

    return (mem_lit_pool + mem_vars + mem_cls +
	    mem_cls_queue + mem_watched + mem_lit_clauses);
}

unsigned CDatabase::mem_usage(void) {
    int mem_lit_pool = (lit_pool_size() + lit_pool_free_space()) * sizeof(CLitPoolElement);

    int mem_vars = sizeof(CVariable) * variables().capacity();

    int mem_cls = sizeof(CClause) * clauses().capacity();

    int mem_cls_queue = sizeof(int) * _unused_clause_idx.size();

    int mem_watched = 0, mem_lit_clauses = 0;

    for (unsigned i=0, sz = variables().size(); i < sz ;  ++i) {
	CVariable & v = variable(i);
	mem_watched	+= v.watched(0).capacity() + v.watched(1).capacity(); 
#ifdef KEEP_LIT_CLAUSES
	mem_lit_clauses += v.lit_clause(0).capacity() + v.lit_clause(1).capacity();
#endif
    }
    mem_watched *= sizeof(CLitPoolElement*);
    mem_lit_clauses *= sizeof(ClauseIdx);
    return (mem_lit_pool + mem_vars + mem_cls + 
	    mem_cls_queue + mem_watched + mem_lit_clauses);
}

int CDatabase::alloc_gid (void)
{
    for (unsigned i=1; i<= WORD_WIDTH; ++i)
	if (is_gid_allocated(i) == false) {
	    _allocated_gid |= (1 << (i-1));
	    return i;
	}
    warning(_POSITION_, "Not enough GID");
    return VOLATILE_GID;
}

void CDatabase::free_gid (int gid) 
{
    assert (gid > 0 && "Can't free volatile or permanent group");
    assert (gid <= WORD_WIDTH && "gid > WORD_WIDTH?" );
    if (is_gid_allocated(gid)==false) {
	fatal(_POSITION_,"Can't free unallocated GID");
    }
    _allocated_gid &= (~(1<< (gid-1)));
}

bool CDatabase::is_gid_allocated(int gid) 
{
    if (gid==VOLATILE_GID || gid==PERMANENT_GID) 
	return true;
    assert (gid<= WORD_WIDTH && gid > 0);	
    if (_allocated_gid & (1 << (gid -1))) 
	return true;
    return false;
}

int CDatabase::merge_clause_group(int g2, int g1) 
{
    assert (g1 >0 && g2> 0 && "Can't merge with permanent or volatile group");
    assert (g1 != g2);
    assert (is_gid_allocated(g1) && is_gid_allocated(g2));
    for (unsigned i=0, sz=clauses().size(); i<sz; ++i) 
	if (clause(i).status() != DELETED_CL)
	    if (clause(i).gid(g1) == true) {
		clause(i).clear_gid(g1);
		clause(i).set_gid(g2);	
	    }
    free_gid (g1);
    return g2;
}

void CDatabase::mark_clause_deleted(CClause & cl) {
    ++_stats.num_deleted_clauses;
    _stats.num_deleted_literals += cl.num_lits();

    CLAUSE_STATUS status=cl.status();
    if(status==ORIGINAL_CL) 
        _stats.num_del_orig_cls++;
    cl.set_status(DELETED_CL);
    for (unsigned i=0; i< cl.num_lits(); ++i) {
	CLitPoolElement & l = cl.literal(i);
	--variable(l.var_index()).lits_count(l.var_sign());
	l.val() = 0;
    }
    _unused_clause_idx.insert( &cl - &(*clauses().begin()));
}

bool CDatabase::is_conflicting(ClauseIdx cl)
{
    CLitPoolElement * lits = clause(cl).literals();
    for (int i=0, sz= clause(cl).num_lits(); i<sz;  ++i)
	if (literal_value(lits[i]) != 0)
	    return false;
    return true;
}

bool CDatabase::is_satisfied(ClauseIdx cl)
{
    CLitPoolElement * lits = clause(cl).literals();
    for (int i=0, sz= clause(cl).num_lits(); i<sz; ++i) 
	if (literal_value(lits[i]) == 1) 
	    return true;
    return false;
}

bool CDatabase::is_unit (ClauseIdx cl)
{
    int num_unassigned = 0;
    CLitPoolElement * lits = clause(cl).literals();
    for (int i=0, sz= clause(cl).num_lits(); i<sz;  ++i) {
	int value = literal_value(lits[i]);
	if (value == 1)
	    return false;
	else if (value != 0)
	    ++ num_unassigned; 
    }
    return ( num_unassigned == 1);
}

int CDatabase::find_unit_literal(ClauseIdx cl) 
//will return 0 if not unit
{
    int unit_lit = 0;
    for (int i=0, sz= clause(cl).num_lits(); i<sz;  ++i) {
	int value =literal_value(clause(cl).literal(i));
	if ( value == 1)
	    return 0;
	else if (value != 0) {
	    if (unit_lit == 0)
		unit_lit = clause(cl).literals()[i].s_var();
	    else 
		return 0;
	}
    }
    return unit_lit;
}

CLitPoolElement * CDatabase::lit_pool_begin(void) 
{ 
    return _lit_pool_start; 
}

CLitPoolElement * CDatabase::lit_pool_end(void) 
{ 
    return _lit_pool_finish; 
}

void CDatabase::lit_pool_incr_size( int size) 
{
    _lit_pool_finish += size; 
    assert (_lit_pool_finish <= _lit_pool_end_storage);
}

void CDatabase::lit_pool_push_back(int value) 
{ 
    assert (_lit_pool_finish <= _lit_pool_end_storage );
    _lit_pool_finish->val() = value;
    ++ _lit_pool_finish;
}

int CDatabase::lit_pool_size(void) 
{ 
    return _lit_pool_finish - _lit_pool_start; 
}

int CDatabase::lit_pool_free_space(void) 
{ 
    return _lit_pool_end_storage - _lit_pool_finish; 
}

double CDatabase::lit_pool_utilization(void) 
{
    //minus num_clauses() is because of spacing (i.e. clause indices)