+#include <threads.h>
+#include <stdlib.h>
+#include "librace.h"
+#include "model-assert.h"
+
+#include "my_stack.h"
+
+#define MAX_FREELIST 4 /* Each thread can own up to MAX_FREELIST free nodes */
+#define INITIAL_FREE 2 /* Each thread starts with INITIAL_FREE free nodes */
+
+#define POISON_IDX 0x666
+
+static unsigned int (*free_lists)[MAX_FREELIST];
+
+/* Search this thread's free list for a "new" node */
+static unsigned int new_node()
+{
+ int i;
+ int t = get_thread_num();
+ for (i = 0; i < MAX_FREELIST; i++) {
+ //unsigned int node = load_32(&free_lists[t][i]);
+ unsigned int node = free_lists[t][i];
+ if (node) {
+ //store_32(&free_lists[t][i], 0);
+ free_lists[t][i] = 0;
+ return node;
+ }
+ }
+ /* free_list is empty? */
+ MODEL_ASSERT(0);
+ return 0;
+}
+
+/* Place this node index back on this thread's free list */
+static void reclaim(unsigned int node)
+{
+ int i;
+ int t = get_thread_num();
+
+ /* Don't reclaim NULL node */
+ //MODEL_ASSERT(node);
+
+ for (i = 0; i < MAX_FREELIST; i++) {
+ /* Should never race with our own thread here */
+ //unsigned int idx = load_32(&free_lists[t][i]);
+ unsigned int idx = free_lists[t][i];
+
+ /* Found empty spot in free list */
+ if (idx == 0) {
+ //store_32(&free_lists[t][i], node);
+ free_lists[t][i] = node;
+ return;
+ }
+ }
+ /* free list is full? */
+ MODEL_ASSERT(0);
+}
+
+void init_stack(stack_t *s, int num_threads)
+{
+ int i, j;
+
+ /* Initialize each thread's free list with INITIAL_FREE pointers */
+ /* The actual nodes are initialized with poison indexes */
+ free_lists = malloc(num_threads * sizeof(*free_lists));
+ for (i = 0; i < num_threads; i++) {
+ for (j = 0; j < INITIAL_FREE; j++) {
+ free_lists[i][j] = 1 + i * MAX_FREELIST + j;
+ atomic_init(&s->nodes[free_lists[i][j]].next, MAKE_POINTER(POISON_IDX, 0));
+ }
+ }
+
+ /* initialize stack */
+ atomic_init(&s->top, MAKE_POINTER(0, 0));
+}
+
+void push(stack_t *s, unsigned int val) {
+ unsigned int nodeIdx = new_node();
+ node_t *node = &s->nodes[nodeIdx];
+ node->value = val;
+ pointer oldTop, newTop;
+ bool success;
+ while (true) {
+ // acquire
+ oldTop = atomic_load_explicit(&s->top, acquire);
+ newTop = MAKE_POINTER(nodeIdx, get_count(oldTop) + 1);
+ // relaxed
+ atomic_store_explicit(&node->next, oldTop, relaxed);
+
+ // release & relaxed
+ success = atomic_compare_exchange_strong_explicit(&s->top, &oldTop,
+ newTop, release, relaxed);
+ if (success)
+ break;
+ }
+}
+
+unsigned int pop(stack_t *s)
+{
+ pointer oldTop, newTop, next;
+ node_t *node;
+ bool success;
+ int val;
+ while (true) {
+ // acquire
+ oldTop = atomic_load_explicit(&s->top, acquire);
+ if (get_ptr(oldTop) == 0)
+ return 0;
+ node = &s->nodes[get_ptr(oldTop)];
+ // relaxed
+ next = atomic_load_explicit(&node->next, relaxed);
+ newTop = MAKE_POINTER(get_ptr(next), get_count(oldTop) + 1);
+ // release & relaxed
+ success = atomic_compare_exchange_strong_explicit(&s->top, &oldTop,
+ newTop, release, relaxed);
+ if (success)
+ break;
+ }
+ val = node->value;
+ /* Reclaim the used slot */
+ reclaim(get_ptr(oldTop));
+ return val;
+}
projects / model-checker-benchmarks.git / commitdiff