4 #include "model-assert.h"
9 #define MAX_FREELIST 4 /* Each thread can own up to MAX_FREELIST free nodes */
10 #define INITIAL_FREE 2 /* Each thread starts with INITIAL_FREE free nodes */
12 #define POISON_IDX 0x666
14 static unsigned int (*free_lists)[MAX_FREELIST];
16 /* Search this thread's free list for a "new" node */
17 static unsigned int new_node()
20 int t = get_thread_num();
21 for (i = 0; i < MAX_FREELIST; i++) {
22 //unsigned int node = load_32(&free_lists[t][i]);
23 unsigned int node = free_lists[t][i];
25 //store_32(&free_lists[t][i], 0);
30 /* free_list is empty? */
35 /* Place this node index back on this thread's free list */
36 static void reclaim(unsigned int node)
39 int t = get_thread_num();
41 /* Don't reclaim NULL node */
44 for (i = 0; i < MAX_FREELIST; i++) {
45 /* Should never race with our own thread here */
46 //unsigned int idx = load_32(&free_lists[t][i]);
47 unsigned int idx = free_lists[t][i];
49 /* Found empty spot in free list */
51 //store_32(&free_lists[t][i], node);
52 free_lists[t][i] = node;
56 /* free list is full? */
60 void init_stack(stack_t *s, int num_threads)
64 /* Initialize each thread's free list with INITIAL_FREE pointers */
65 /* The actual nodes are initialized with poison indexes */
66 free_lists = malloc(num_threads * sizeof(*free_lists));
67 for (i = 0; i < num_threads; i++) {
68 for (j = 0; j < INITIAL_FREE; j++) {
69 free_lists[i][j] = 1 + i * MAX_FREELIST + j;
70 atomic_init(&s->nodes[free_lists[i][j]].next, MAKE_POINTER(POISON_IDX, 0));
74 /* initialize stack */
75 atomic_init(&s->top, MAKE_POINTER(0, 0));
78 void push(stack_t *s, unsigned int val) {
79 unsigned int nodeIdx = new_node();
80 node_t *node = &s->nodes[nodeIdx];
82 pointer oldTop, newTop;
86 oldTop = atomic_load_explicit(&s->top, wildcard(1));
87 newTop = MAKE_POINTER(nodeIdx, get_count(oldTop) + 1);
89 atomic_store_explicit(&node->next, oldTop, wildcard(2));
92 success = atomic_compare_exchange_strong_explicit(&s->top, &oldTop,
93 newTop, wildcard(3), wildcard(4));
99 unsigned int pop(stack_t *s)
101 pointer oldTop, newTop, next;
107 oldTop = atomic_load_explicit(&s->top, wildcard(5));
108 if (get_ptr(oldTop) == 0)
110 node = &s->nodes[get_ptr(oldTop)];
112 next = atomic_load_explicit(&node->next, wildcard(6));
113 newTop = MAKE_POINTER(get_ptr(next), get_count(oldTop) + 1);
115 success = atomic_compare_exchange_strong_explicit(&s->top, &oldTop,
116 newTop, wildcard(7), wildcard(8));
121 /* Reclaim the used slot */
122 reclaim(get_ptr(oldTop));