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pb/car constraints

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2013-11-07 00:53:08 -08:00
parent 55e91c099f
commit 3ee8c3efb5
6 changed files with 494 additions and 298 deletions
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553
src/smt/theory_card.cpp
View file

@ -97,25 +97,9 @@ namespace smt {
ctx.mk_th_axiom(get_id(), 1, &lit);
ctx.mark_as_relevant(tmp);
}
c->m_args.push_back(bv);
if (0 < k) {
add_watch(bv, c);
}
}
if (0 < k) {
add_card(c);
}
else {
// bv <=> (and (not bv1) ... (not bv_n))
literal_vector& lits = get_lits();
lits.push_back(literal(abv));
for (unsigned i = 0; i < c->m_args.size(); ++i) {
ctx.mk_th_axiom(get_id(), ~literal(abv), ~literal(c->m_args[i]));
lits.push_back(literal(c->m_args[i]));
}
ctx.mk_th_axiom(get_id(), lits.size(), lits.c_ptr());
dealloc(c);
c->m_args.push_back(std::make_pair(bv,1));
}
add_card(c);
return true;
}
@ -128,6 +112,49 @@ namespace smt {
cards->push_back(c);
m_watch_trail.push_back(bv);
}
void theory_card::add_card(card* c) {
bool_var abv = c->m_bv;
arg_t& args = c->m_args;
// sort and coalesce arguments:
std::sort(args.begin(), args.end());
for (unsigned i = 0; i + 1 < args.size(); ++i) {
if (args[i].first == args[i+1].first) {
args[i].second += args[i+1].second;
for (unsigned j = i+1; j + 1 < args.size(); ++j) {
args[j] = args[j+1];
}
args.resize(args.size()-1);
}
if (args[i].second == 0) {
for (unsigned j = i; j + 1 < args.size(); ++j) {
args[j] = args[j+1];
}
args.resize(args.size()-1);
}
}
int min = 0, max = 0;
for (unsigned i = 0; i < args.size(); ++i) {
// update min and max:
int inc = args[i].second;
if (inc > 0) {
max += inc;
}
else {
SASSERT(inc < 0);
min += inc;
}
// add watch literals:
add_watch(args[i].first, c);
}
c->m_current_min = c->m_abs_min = min;
c->m_current_max = c->m_abs_max = max;
m_cards.insert(abv, c);
m_cards_trail.push_back(abv);
}
void theory_card::reset_eh() {
@ -149,6 +176,172 @@ namespace smt {
m_watch_lim.reset();
}
void theory_card::update_min_max(bool_var v, bool is_true, card* c) {
context& ctx = get_context();
ast_manager& m = get_manager();
arg_t const& args = c->m_args;
int inc = find_inc(v, args);
int& min = c->m_current_min;
int& max = c->m_current_max;
int k = c->m_k;
// inc > 0 & is_true -> min += inc
// inc < 0 & is_true -> max += inc
// inc > 0 & !is_true -> max -= inc
// inc < 0 & !is_true -> min -= inc
if (inc > 0 && is_true) {
ctx.push_trail(value_trail<context, int>(min));
min += inc;
}
else if (inc < 0 && is_true) {
ctx.push_trail(value_trail<context, int>(max));
max += inc;
}
else if (inc > 0 && !is_true) {
ctx.push_trail(value_trail<context, int>(max));
max -= inc;
}
else {
ctx.push_trail(value_trail<context, int>(min));
min -= inc;
}
// invariant min <= max
SASSERT(min <= max);
}
void theory_card::assign_use(bool_var v, bool is_true, card* c) {
update_min_max(v, is_true, c);
propagate_assignment(c);
}
lbool theory_card::inc_min(int inc, lbool val) {
if (inc > 0) {
return val;
}
else if (inc < 0) {
return ~val;
}
else {
return l_undef;
}
}
lbool theory_card::dec_max(int inc, lbool val) {
if (inc > 0) {
return ~val;
}
else if (inc < 0) {
return val;
}
else {
return l_undef;
}
}
int theory_card::accumulate_min(literal_vector& lits, card* c) {
context& ctx = get_context();
int k = c->m_k;
arg_t const& args = c->m_args;
int curr_min = c->m_abs_min;
for (unsigned i = 0; i < args.size() && curr_min <= k; ++i) {
bool_var bv = args[i].first;
int inc = args[i].second;
lbool val = ctx.get_assignment(bv);
if (inc_min(inc, val) == l_true) {
curr_min += abs(inc);
lits.push_back(literal(bv, val != l_true));
}
}
return curr_min;
}
int theory_card::accumulate_max(literal_vector& lits, card* c) {
context& ctx = get_context();
arg_t const& args = c->m_args;
int k = c->m_k;
int curr_max = c->m_abs_max;
for (unsigned i = 0; i < args.size() && k < curr_max; ++i) {
bool_var bv = args[i].first;
int inc = args[i].second;
lbool val = ctx.get_assignment(bv);
if (dec_max(inc, val) == l_true) {
curr_max -= abs(inc);
lits.push_back(literal(bv, val == l_true));
}
}
return curr_max;
}
void theory_card::propagate_assignment(card* c) {
context& ctx = get_context();
arg_t const& args = c->m_args;
bool_var abv = c->m_bv;
int min = c->m_current_min;
int max = c->m_current_max;
int k = c->m_k;
//
// if min > k && abv != l_false -> force abv false
// if max <= k && abv != l_true -> force abv true
// if min == k && abv == l_true -> force positive unassigned literals false
// if max == k + 1 && abv == l_false -> force negative unassigned literals false
//
lbool aval = ctx.get_assignment(abv);
if (min > k && aval != l_false) {
literal_vector& lits = get_lits();
lits.push_back(~literal(abv));
int curr_min = accumulate_min(lits, c);
SASSERT(curr_min > k);
add_clause(lits);
}
else if (max <= k && aval != l_true) {
literal_vector& lits = get_lits();
lits.push_back(literal(abv));
int curr_max = accumulate_max(lits, c);
SASSERT(curr_max <= k);
add_clause(lits);
}
else if (min == k && aval == l_true) {
literal_vector& lits = get_lits();
lits.push_back(~literal(abv));
int curr_min = accumulate_min(lits, c);
if (curr_min > k) {
add_clause(lits);
}
else {
SASSERT(curr_min == k);
for (unsigned i = 0; i < args.size(); ++i) {
bool_var bv = args[i].first;
int inc = args[i].second;
if (inc_min(inc, ctx.get_assignment(bv)) == l_undef) {
lits.push_back(literal(bv, inc > 0)); // avoid incrementing min.
add_clause(lits);
lits.pop_back();
}
}
}
}
else if (max == k + 1 && aval == l_false) {
literal_vector& lits = get_lits();
lits.push_back(literal(abv));
int curr_max = accumulate_max(lits, c);
if (curr_max <= k) {
add_clause(lits);
}
else if (curr_max == k + 1) {
for (unsigned i = 0; i < args.size(); ++i) {
bool_var bv = args[i].first;
int inc = args[i].second;
if (dec_max(inc, ctx.get_assignment(bv)) == l_undef) {
lits.push_back(literal(bv, inc < 0)); // avoid decrementing max.
add_clause(lits);
lits.pop_back();
}
}
}
}
}
void theory_card::assign_eh(bool_var v, bool is_true) {
context& ctx = get_context();
ast_manager& m = get_manager();
@ -158,125 +351,33 @@ namespace smt {
if (m_watch.find(v, cards)) {
for (unsigned i = 0; i < cards->size(); ++i) {
c = (*cards)[i];
svector<bool_var> const& args = c->m_args;
//
// is_true && m_t + 1 > k -> force false
// !is_true && m_f + 1 >= arity - k -> force true
//
if (is_true && c->m_t >= c->m_k) {
unsigned k = c->m_k;
// force false
switch (ctx.get_assignment(c->m_bv)) {
case l_true:
case l_undef: {
literal_vector& lits = get_lits();
lits.push_back(~literal(c->m_bv));
for (unsigned i = 0; i < args.size() && lits.size() < k + 1; ++i) {
if (ctx.get_assignment(args[i]) == l_true) {
lits.push_back(~literal(args[i]));
}
}
SASSERT(lits.size() == k + 1);
add_clause(lits);
break;
}
default:
break;
}
}
else if (!is_true && c->m_k >= args.size() - c->m_f - 1) {
// forced true
switch (ctx.get_assignment(c->m_bv)) {
case l_false:
case l_undef: {
unsigned deficit = args.size() - c->m_k;
literal_vector& lits = get_lits();
lits.push_back(literal(c->m_bv));
for (unsigned i = 0; i < args.size() && lits.size() <= deficit; ++i) {
if (ctx.get_assignment(args[i]) == l_false) {
lits.push_back(literal(args[i]));
}
}
add_clause(lits);
break;
}
default:
break;
}
}
else if (is_true) {
ctx.push_trail(value_trail<context, unsigned>(c->m_t));
c->m_t++;
}
else {
ctx.push_trail(value_trail<context, unsigned>(c->m_f));
c->m_f++;
}
assign_use(v, is_true, (*cards)[i]);
}
}
if (m_cards.find(v, c)) {
svector<bool_var> const& args = c->m_args;
SASSERT(args.size() >= c->m_f + c->m_t);
bool_var bv;
propagate_assignment(c);
}
}
TRACE("card", tout << " t:" << is_true << " k:" << c->m_k << " t:" << c->m_t << " f:" << c->m_f << "\n";);
// at most k
// propagate false to children that are not yet assigned.
// v & t1 & ... & tk => ~l_j
if (is_true && c->m_k <= c->m_t) {
literal_vector& lits = get_lits();
lits.push_back(literal(v));
bool done = false;
for (unsigned i = 0; !done && i < args.size(); ++i) {
bv = args[i];
if (ctx.get_assignment(bv) == l_true) {
lits.push_back(literal(bv));
}
if (lits.size() > c->m_k + 1) {
add_clause(lits);
done = true;
}
}
SASSERT(done || lits.size() == c->m_k + 1);
for (unsigned i = 0; !done && i < args.size(); ++i) {
bv = args[i];
if (ctx.get_assignment(bv) == l_undef) {
lits.push_back(literal(bv));
add_clause(lits);
lits.pop_back();
}
}
int theory_card::find_inc(bool_var bv, svector<std::pair<bool_var, int> >const& vars) {
unsigned mid = vars.size()/2;
unsigned lo = 0;
unsigned hi = vars.size()-1;
while (lo < hi) {
if (vars[mid].first == bv) {
return vars[mid].second;
}
// at least k+1:
// !v & !f1 & .. & !f_m => l_j
// for m + k + 1 = arity()
if (!is_true && args.size() <= 1 + c->m_f + c->m_k) {
literal_vector& lits = get_lits();
lits.push_back(literal(v));
bool done = false;
for (unsigned i = 0; !done && i < args.size(); ++i) {
bv = args[i];
if (ctx.get_assignment(bv) == l_false) {
lits.push_back(literal(bv));
}
if (lits.size() > c->m_k + 1) {
add_clause(lits);
done = true;
}
}
for (unsigned i = 0; !done && i < args.size(); ++i) {
bv = args[i];
if (ctx.get_assignment(bv) != l_false) {
lits.push_back(~literal(bv));
add_clause(lits);
lits.pop_back();
}
}
else if (vars[mid].first < bv) {
lo = mid;
mid += (hi-mid)/2;
}
else {
hi = mid;
mid = (mid-lo)/2 + lo;
}
}
SASSERT(vars[mid].first == bv);
return vars[mid].second;
}
void theory_card::init_search_eh() {
@ -319,151 +420,79 @@ namespace smt {
ctx.mk_th_axiom(get_id(), lits.size(), lits.c_ptr());
}
#if 1
#endif
}
#if 0
class sorting_network {
ast_manager& m;
expr_ref_vector m_es;
expr_ref_vector* m_current;
expr_ref_vector* m_next;
void exchange(unsigned i, unsigned j, expr_ref_vector& es) {
SASSERT(i <= j);
if (i == j) {
return;
}
expr* ei = es[i].get();
expr* ej = es[j].get();
es[i] = m.mk_ite(mk_le(ei,ej), ei, ej);
es[j] = m.mk_ite(mk_le(ej,ei), ei, ej);
}
void sort(unsigned k) {
if (k == 2) {
for (unsigned i = 0; i < m_es.size()/2; ++i) {
exchange(current(2*i), current(2*i+1), m_es);
next(2*i) = current(2*i);
next(2*i+1) = current(2*i+1);
expr_ref_vector merge(expr_ref_vector const& l1, expr_ref_vector const& l2) {
if (l1.empty()) {
return l2;
}
std::swap(m_current, m_next);
}
else {
for (unsigned i = 0; i < m_es.size()/k; ++i) {
for (unsigned j = 0; j < k / 2; ++j) {
next((k * i) + j) = current((k * i) + (2 * j));
next((k * i) + (k / 2) + j) = current((k * i) + (2 * j) + 1);
}
if (l2.empty()) {
return l1;
}
std::swap(m_current, m_next);
sort(k / 2);
for (unsigned i = 0; i < m_es.size() / k; ++i) {
for (unsigned j = 0; j < k / 2; ++j) {
next((k * i) + (2 * j)) = current((k * i) + j);
next((k * i) + (2 * j) + 1) = current((k * i) + (k / 2) + j);
}
for (unsigned j = 0; j < (k / 2) - 1; ++j) {
exchange(next((k * i) + (2 * j) + 1), next((k * i) + (2 * (j + 1))));
}
expr_ref_vector result(m);
if (l1.size() == 1 && l2.size() == 1) {
result.push_back(l1[0]);
result.push_back(l2[0]);
exchange(0, 1, result);
return result;
}
std::swap(m_current, m_next);
}
}
expr_ref_vector merge(expr_ref_vector const& l1, expr_ref_vector& l2) {
if (l1.empty()) {
return l2;
}
if (l2.empty()) {
return l1;
}
expr_ref_vector result(m);
if (l1.size() == 1 && l2.size() == 1) {
result.push_back(l1[0]);
result.push_back(l2[0]);
exchange(0, 1, result);
return result;
}
unsigned l1o = l1.size()/2;
unsigned l2o = l2.size()/2;
unsigned l1e = (l1.size() % 2 == 1) ? l1o + 1 : l1o;
unsigned l2e = (l2.size() % 2 == 1) ? l2o + 1 : l2o;
expr_ref_vector evenl1(m, l1e);
expr_ref_vector oddl1(m, l1o);
expr_ref_vector evenl2(m, l2e);
expr_ref_vector oddl2(m, l2o);
for (unsigned i = 0; i < l1.size(); ++i) {
if (i % 2 == 0) {
evenl1[i/2] = l1[i];
}
else {
oddl1[i/2] = l1[i];
}
}
for (unsigned i = 0; i < l2.size(); ++i) {
if (i % 2 == 0) {
evenl2[i/2] = l2[i];
}
else {
oddl2[i/2] = l2[i];
}
}
expr_ref_vector even = merge(evenl1, evenl2);
expr_ref_vector odd = merge(oddl1, oddl2);
result.resize(l1.size() + l2.size());
for (unsigned i = 0; i < result.size(); ++i) {
if (i % 2 == 0) {
result[i] = even[i/2].get();
if (i > 0) {
exchange(i - 1, i, result);
}
}
else {
if (i /2 < odd.size()) {
result[i] = odd[i/2].get();
unsigned l1o = l1.size()/2;
unsigned l2o = l2.size()/2;
unsigned l1e = (l1.size() % 2 == 1) ? l1o + 1 : l1o;
unsigned l2e = (l2.size() % 2 == 1) ? l2o + 1 : l2o;
expr_ref_vector evenl1(m), oddl1(m), evenl2(m), oddl2(m);
evenl1.resize(l1e);
oddl1.resize(l1o);
evenl2.resize(l2e);
oddl2.resize(l2o);
for (unsigned i = 0; i < l1.size(); ++i) {
if (i % 2 == 0) {
evenl1[i/2] = l1[i];
}
else {
result[i] = even[(i/2)+1].get();
oddl1[i/2] = l1[i];
}
}
}
return result;
}
for (unsigned i = 0; i < l2.size(); ++i) {
if (i % 2 == 0) {
evenl2[i/2] = l2[i];
}
else {
oddl2[i/2] = l2[i];
}
}
expr_ref_vector even = merge(evenl1, evenl2);
expr_ref_vector odd = merge(oddl1, oddl2);
public:
sorting_network(ast_manager& m):
m(m),
m_es(m),
m_current(0),
m_next(0)
{}
expr_ref_vector operator()(expr_ref_vector const& inputs) {
if (inputs.size() <= 1) {
return inputs;
result.resize(l1.size() + l2.size());
for (unsigned i = 0; i < result.size(); ++i) {
if (i % 2 == 0) {
result[i] = even[i/2].get();
if (i > 0) {
exchange(i - 1, i, result);
}
}
else {
if (i /2 < odd.size()) {
result[i] = odd[i/2].get();
}
else {
result[i] = even[(i/2)+1].get();
}
}
}
return result;
}
m_es.reset();
m_es.append(inputs);
while (!is_power_of2(m_es.size())) {
m_es.push_back(m.mk_false());
}
m_es.reverse();
for (unsigned i = 0; i < m_es.size(); ++i) {
current(i) = i;
}
unsigned k = 2;
while (k <= m_es.size()) {
sort(k);
// TBD
k *= 2;
}
}
};
Sorting networks used in Formula:

29
src/smt/theory_card.h
View file

@ -25,14 +25,19 @@ Notes:
namespace smt {
class theory_card : public theory {
typedef svector<std::pair<bool_var, int> > arg_t;
struct card {
unsigned m_k;
int m_k;
bool_var m_bv;
unsigned m_t;
unsigned m_f;
svector<bool_var> m_args;
int m_current_min;
int m_current_max;
int m_abs_min;
int m_abs_max;
arg_t m_args;
card(bool_var bv, unsigned k):
m_k(k), m_bv(bv), m_t(0), m_f(0)
m_k(k), m_bv(bv)
{}
};
@ -46,13 +51,19 @@ namespace smt {
card_util m_util;
void add_watch(bool_var bv, card* c);
void add_card(card* c);
void add_card(card* c) {
m_cards.insert(c->m_bv, c);
m_cards_trail.push_back(c->m_bv);
}
void add_clause(literal_vector const& lits);
literal_vector& get_lits();
int find_inc(bool_var bv, svector<std::pair<bool_var, int> >const& vars);
void theory_card::propagate_assignment(card* c);
int theory_card::accumulate_max(literal_vector& lits, card* c);
int theory_card::accumulate_min(literal_vector& lits, card* c);
lbool theory_card::dec_max(int inc, lbool val);
lbool theory_card::inc_min(int inc, lbool val);
void theory_card::assign_use(bool_var v, bool is_true, card* c);
void theory_card::update_min_max(bool_var v, bool is_true, card* c);
public:
theory_card(ast_manager& m);

50
src/tactic/arith/lia2card_tactic.cpp
View file

@ -175,54 +175,48 @@ class lia2card_tactic : public tactic {
if (a.is_le(fml, x, y) || a.is_ge(fml, y, x)) {
if (is_01var(x) && a.is_numeral(y, n)) {
sub.insert(fml, mk_le(x, n));
return;
}
if (is_01var(y) && a.is_numeral(x, n)) {
else if (is_01var(y) && a.is_numeral(x, n)) {
sub.insert(fml, mk_ge(y, n));
return;
}
if (is_add(x, args) && is_unsigned(y, k)) { // x <= k
else if (is_add(x, args) && is_unsigned(y, k)) { // x <= k
sub.insert(fml, m_card.mk_at_most_k(args.size(), args.c_ptr(), k));
return;
}
if (is_add(y, args) && is_unsigned(x, k)) { // k <= y <=> not (y <= k-1)
else if (is_add(y, args) && is_unsigned(x, k)) { // k <= y <=> not (y <= k-1)
if (k == 0)
sub.insert(fml, m.mk_true());
else
sub.insert(fml, m.mk_not(m_card.mk_at_most_k(args.size(), args.c_ptr(), k-1)));
return;
}
UNREACHABLE();
else {
UNREACHABLE();
}
}
if (a.is_lt(fml, x, y) || a.is_gt(fml, y, x)) {
else if (a.is_lt(fml, x, y) || a.is_gt(fml, y, x)) {
if (is_01var(x) && a.is_numeral(y, n)) {
sub.insert(fml, mk_le(x, n-rational(1)));
return;
}
if (is_01var(y) && a.is_numeral(x, n)) {
else if (is_01var(y) && a.is_numeral(x, n)) {
sub.insert(fml, mk_ge(y, n+rational(1)));
return;
}
if (is_add(x, args) && is_unsigned(y, k)) { // x < k
else if (is_add(x, args) && is_unsigned(y, k)) { // x < k
if (k == 0)
sub.insert(fml, m.mk_false());
else
sub.insert(fml, m_card.mk_at_most_k(args.size(), args.c_ptr(), k-1));
return;
}
if (is_add(y, args) && is_unsigned(x, k)) { // k < y <=> not (y <= k)
}
else if (is_add(y, args) && is_unsigned(x, k)) { // k < y <=> not (y <= k)
sub.insert(fml, m.mk_not(m_card.mk_at_most_k(args.size(), args.c_ptr(), k)));
return;
}
UNREACHABLE();
else {
UNREACHABLE();
}
}
if (m.is_eq(fml, x, y)) {
else if (m.is_eq(fml, x, y)) {
if (!is_01var(x)) {
std::swap(x, y);
}
if (is_01var(x) && a.is_numeral(y, n)) {
else if (is_01var(x) && a.is_numeral(y, n)) {
if (n.is_one()) {
sub.insert(fml, mk_01(x));
}
@ -232,19 +226,21 @@ class lia2card_tactic : public tactic {
else {
sub.insert(fml, m.mk_false());
}
return;
}
UNREACHABLE();
else {
UNREACHABLE();
}
}
if (is_sum(fml)) {
else if (is_sum(fml)) {
SASSERT(m_uses.contains(fml));
ptr_vector<expr> const& u = m_uses.find(fml);
for (unsigned i = 0; i < u.size(); ++i) {
convert_01(sub, u[i]);
}
return;
}
UNREACHABLE();
else {
UNREACHABLE();
}
}
expr_ref mk_01(expr* x) {

1
src/test/main.cpp
View file

@ -216,6 +216,7 @@ int main(int argc, char ** argv) {
TST(polynorm);
TST(qe_arith);
TST(expr_substitution);
TST(sorting_network);
}
void initialize_mam() {}

60
src/test/sorting_network.cpp Normal file
View file

@ -0,0 +1,60 @@
#include "sorting_network.h"
#include "vector.h"
#include "ast.h"
struct ast_ext {
ast_manager& m;
ast_ext(ast_manager& m):m(m) {}
typedef expr* T;
typedef expr_ref_vector vector;
T mk_ite(T a, T b, T c) {
return m.mk_ite(a, b, c);
}
T mk_le(T a, T b) {
if (m.is_bool(a)) {
return m.mk_implies(a, b);
}
UNREACHABLE();
return 0;
}
T mk_default() {
return m.mk_false();
}
};
struct unsigned_ext {
unsigned_ext() {}
typedef unsigned T;
typedef svector<unsigned> vector;
T mk_ite(T a, T b, T c) {
return (a==1)?b:c;
}
T mk_le(T a, T b) {
return (a <= b)?1:0;
}
T mk_default() {
return 0;
}
};
void tst_sorting_network() {
svector<unsigned> vec;
unsigned_ext uext;
sorting_network<unsigned_ext> sn(uext, vec);
svector<unsigned> in1;
in1.push_back(0);
in1.push_back(1);
in1.push_back(0);
in1.push_back(1);
in1.push_back(1);
in1.push_back(0);
sn(in1);
for (unsigned i = 0; i < vec.size(); ++i) {
std::cout << vec[i];
}
std::cout << "\n";
}

99
src/util/sorting_network.h Normal file
View file

@ -0,0 +1,99 @@
#include "vector.h"
#ifndef _SORTING_NETWORK_H_
#define _SORTING_NETWORK_H_
template <typename Ext>
class sorting_network {
typename Ext::vector& m_es;
Ext& m_ext;
svector<unsigned> m_currentv;
svector<unsigned> m_nextv;
svector<unsigned>* m_current;
svector<unsigned>* m_next;
unsigned& current(unsigned i) { return (*m_current)[i]; }
unsigned& next(unsigned i) { return (*m_next)[i]; }
void exchange(unsigned i, unsigned j) {
SASSERT(i <= j);
if (i < j) {
Ext::T ei = m_es.get(i);
Ext::T ej = m_es.get(j);
m_es.set(i, m_ext.mk_ite(m_ext.mk_le(ei, ej), ei, ej));
m_es.set(j, m_ext.mk_ite(m_ext.mk_le(ej, ei), ei, ej));
}
}
void sort(unsigned k) {
SASSERT(is_power_of2(k) && k > 0);
if (k == 2) {
for (unsigned i = 0; i < m_es.size()/2; ++i) {
exchange(current(2*i), current(2*i+1));
next(2*i) = current(2*i);
next(2*i+1) = current(2*i+1);
}
std::swap(m_current, m_next);
}
else {
for (unsigned i = 0; i < m_es.size()/k; ++i) {
unsigned ki = k * i;
for (unsigned j = 0; j < k / 2; ++j) {
next(ki + j) = current(ki + (2 * j));
next(ki + (k / 2) + j) = current(ki + (2 * j) + 1);
}
}
std::swap(m_current, m_next);
sort(k / 2);
for (unsigned i = 0; i < m_es.size() / k; ++i) {
unsigned ki = k * i;
for (unsigned j = 0; j < k / 2; ++j) {
next(ki + (2 * j)) = current(ki + j);
next(ki + (2 * j) + 1) = current(ki + (k / 2) + j);
}
for (unsigned j = 0; j < (k / 2) - 1; ++j) {
exchange(next(ki + (2 * j) + 1), next(ki + (2 * (j + 1))));
}
}
std::swap(m_current, m_next);
}
}
bool is_power_of2(unsigned n) const {
return n != 0 && ((n-1) & n) == 0;
}
public:
sorting_network(Ext& ext, typename Ext::vector& es):
m_ext(ext),
m_es(es),
m_current(&m_currentv),
m_next(&m_nextv)
{}
void operator()(typename Ext::vector const& inputs) {
if (inputs.size() <= 1) {
return;
}
m_es.reset();
m_es.append(inputs);
while (!is_power_of2(m_es.size())) {
m_es.push_back(m_ext.mk_default());
}
for (unsigned i = 0; i < m_es.size(); ++i) {
current(i) = i;
}
unsigned k = 2;
while (k <= m_es.size()) {
sort(k);
k *= 2;
}
}
};
#endif