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decide.c
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decide.c
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#include "decide.h"
#include "assign.h"
#include "macros.h"
#include "message.h"
#include "options.h"
#include "random.h"
#include "ring.h"
#include "utilities.h"
#include <inttypes.h>
signed char initial_phase (struct ring *ring) {
return ring->options.phase ? 1 : -1;
}
signed char decide_phase (struct ring *ring, unsigned idx) {
struct phases *p = ring->phases + idx;
unsigned target = ring->options.target_phases;
signed char res = 0;
if (ring->options.force_phase)
res = initial_phase (ring);
if (!res)
if ((target && ring->stable) || (target > 1 && !ring->stable))
res = p->target;
if (!res)
res = p->saved;
if (!res)
res = initial_phase (ring);
return res;
}
static unsigned random_decision (struct ring *ring) {
assert (ring->unassigned);
signed char *values = ring->values;
bool *inactive = ring->inactive;
unsigned size = ring->size;
unsigned idx = random_modulo (&ring->random, size);
unsigned lit = LIT (idx);
if (inactive[idx] || values[lit]) {
unsigned delta = random_modulo (&ring->random, size);
while (gcd (delta, size) != 1)
if (++delta == size)
delta = 1;
assert (delta < size);
do {
idx += delta;
if (idx >= size)
idx -= size;
lit = LIT (idx);
} while (inactive[idx] || values[lit]);
}
LOG ("random decision %s", LOGVAR (idx));
if (ring->context == SEARCH_CONTEXT)
ring->statistics.decisions.random++;
return idx;
}
static unsigned best_decision_on_heap (struct ring *ring) {
assert (ring->unassigned);
signed char *values = ring->values;
struct heap *heap = &ring->heap;
struct node *nodes = heap->nodes;
unsigned idx;
for (;;) {
struct node *root;
root = heap->root;
assert (root);
assert (root - nodes < ring->size);
idx = root - nodes;
unsigned lit = LIT (idx);
if (!values[lit])
break;
pop_heap (heap);
}
LOG ("best decision %s on heap with score %g", LOGVAR (idx),
nodes[idx].score);
if (ring->context == SEARCH_CONTEXT)
ring->statistics.decisions.heap++;
return idx;
}
static unsigned best_decision_on_queue (struct ring *ring) {
assert (ring->unassigned);
signed char *values = ring->values;
struct queue *queue = &ring->queue;
struct link *links = queue->links;
struct link *search = queue->search;
unsigned lit, idx;
for (;;) {
assert (search);
idx = search - links;
lit = LIT (idx);
if (!values[lit])
break;
search = search->prev;
}
queue->search = search;
LOG ("best decision %s on queue with stamp %" PRIu64, LOGVAR (idx),
search->stamp);
if (ring->context == SEARCH_CONTEXT)
ring->statistics.decisions.queue++;
return idx;
}
void start_random_decision_sequence (struct ring *ring) {
if (!ring->options.random_decisions)
return;
if (ring->stable && !ring->options.random_stable_decisions)
return;
if (!ring->stable && !ring->options.random_focused_decisions)
return;
if (ring->randec)
very_verbose (ring,
"continuing random decision sequence at %" PRIu64
" conflicts",
SEARCH_CONFLICTS);
else {
uint64_t sequences = ++ring->statistics.random_sequences;
unsigned length = ring->options.random_decision_length;
ring->randec = length;
very_verbose (ring,
"starting random decision sequence %" PRIu64
" at %" PRIu64 " conflicts",
sequences, SEARCH_CONFLICTS);
uint64_t base = ring->options.random_decision_interval;
uint64_t interval = base * logn (sequences);
ring->limits.randec = SEARCH_CONFLICTS + interval;
}
}
static unsigned next_random_decision (struct ring *ring) {
if (!ring->size)
return INVALID_VAR;
if (ring->context != SEARCH_CONTEXT)
return INVALID_VAR;
if (!ring->options.random_decisions)
return INVALID_VAR;
if (ring->stable && !ring->options.random_stable_decisions)
return INVALID_VAR;
if (!ring->stable && !ring->options.random_focused_decisions)
return INVALID_VAR;
if (!ring->randec) {
assert (ring->level);
if (ring->level > 1)
return INVALID_VAR;
uint64_t conflicts = SEARCH_CONFLICTS;
if (conflicts < ring->limits.randec)
return INVALID_VAR;
start_random_decision_sequence (ring);
}
return random_decision (ring);
}
void decide (struct ring *ring) {
ring->level++;
unsigned idx = next_random_decision (ring);
if (idx == INVALID_VAR) {
if (ring->stable)
idx = best_decision_on_heap (ring);
else
idx = best_decision_on_queue (ring);
}
signed char phase = decide_phase (ring, idx);
unsigned lit = LIT (idx);
if (phase < 0)
lit = NOT (lit);
struct context *context = ring->statistics.contexts;
context += ring->context;
context->decisions++;
if (ring->context == SEARCH_CONTEXT) {
if (phase < 0)
ring->statistics.decisions.negative++;
else
ring->statistics.decisions.positive++;
}
assign_decision (ring, lit);
}