4 #include "model-assert.h"
8 #define MAX_FREELIST 4 /* Each thread can own up to MAX_FREELIST free nodes */
9 #define INITIAL_FREE 2 /* Each thread starts with INITIAL_FREE free nodes */
11 #define POISON_IDX 0x666
13 static unsigned int (*free_lists)[MAX_FREELIST];
15 /* Search this thread's free list for a "new" node */
16 static unsigned int new_node()
19 int t = get_thread_num();
20 for (i = 0; i < MAX_FREELIST; i++) {
21 //unsigned int node = load_32(&free_lists[t][i]);
22 unsigned int node = free_lists[t][i];
24 //store_32(&free_lists[t][i], 0);
29 /* free_list is empty? */
34 /* Place this node index back on this thread's free list */
35 static void reclaim(unsigned int node)
38 int t = get_thread_num();
40 /* Don't reclaim NULL node */
43 for (i = 0; i < MAX_FREELIST; i++) {
44 /* Should never race with our own thread here */
45 //unsigned int idx = load_32(&free_lists[t][i]);
46 unsigned int idx = free_lists[t][i];
48 /* Found empty spot in free list */
50 //store_32(&free_lists[t][i], node);
51 free_lists[t][i] = node;
55 /* free list is full? */
59 void init_stack(stack_t *s, int num_threads)
63 /* Initialize each thread's free list with INITIAL_FREE pointers */
64 /* The actual nodes are initialized with poison indexes */
65 free_lists = malloc(num_threads * sizeof(*free_lists));
66 for (i = 0; i < num_threads; i++) {
67 for (j = 0; j < INITIAL_FREE; j++) {
68 free_lists[i][j] = 1 + i * MAX_FREELIST + j;
69 atomic_init(&s->nodes[free_lists[i][j]].next, MAKE_POINTER(POISON_IDX, 0));
73 /* initialize stack */
74 atomic_init(&s->top, MAKE_POINTER(0, 0));
77 void push(stack_t *s, unsigned int val) {
78 unsigned int nodeIdx = new_node();
79 node_t *node = &s->nodes[nodeIdx];
81 pointer oldTop, newTop;
85 oldTop = atomic_load_explicit(&s->top, acquire);
86 newTop = MAKE_POINTER(nodeIdx, get_count(oldTop) + 1);
88 atomic_store_explicit(&node->next, oldTop, relaxed);
91 success = atomic_compare_exchange_strong_explicit(&s->top, &oldTop,
92 newTop, release, relaxed);
98 unsigned int pop(stack_t *s)
100 pointer oldTop, newTop, next;
106 oldTop = atomic_load_explicit(&s->top, acquire);
107 if (get_ptr(oldTop) == 0)
109 node = &s->nodes[get_ptr(oldTop)];
111 next = atomic_load_explicit(&node->next, relaxed);
112 newTop = MAKE_POINTER(get_ptr(next), get_count(oldTop) + 1);
114 success = atomic_compare_exchange_strong_explicit(&s->top, &oldTop,
115 newTop, release, relaxed);
120 /* Reclaim the used slot */
121 reclaim(get_ptr(oldTop));