8 Deque * q = (Deque *) calloc(1, sizeof(Deque));
9 Array * a = (Array *) calloc(1, sizeof(Array)+2*sizeof(atomic_int));
10 atomic_store_explicit(&q->array, a, memory_order_relaxed);
11 atomic_store_explicit(&q->top, 0, memory_order_relaxed);
12 atomic_store_explicit(&q->bottom, 0, memory_order_relaxed);
13 atomic_store_explicit(&a->size, 2, memory_order_relaxed);
20 @Interface_define: Take
24 size_t b = atomic_load_explicit(&q->bottom, memory_order_relaxed) - 1;
25 Array *a = (Array *) atomic_load_explicit(&q->array, memory_order_relaxed);
26 atomic_store_explicit(&q->bottom, b, memory_order_relaxed);
27 atomic_thread_fence(memory_order_seq_cst);
28 size_t t = atomic_load_explicit(&q->top, memory_order_relaxed);
31 @Commit_point_define_check: t > b
37 /* Non-empty queue. */
38 int size = atomic_load_explicit(&a->size, memory_order_relaxed);
40 model_print("take: size == 0\n");
41 // TODO: size can be zero here!!
42 x = atomic_load_explicit(&a->buffer[b % size], memory_order_relaxed);
45 @Commit_point_define_check: t != b
50 /* Single last element in queue. */
51 bool succ = atomic_compare_exchange_strong_explicit(&q->top, &t, t +
52 1, memory_order_seq_cst, memory_order_relaxed);
55 @Commit_point_define_check: succ == true
62 @Commit_point_define_check: succ == false
70 atomic_store_explicit(&q->bottom, b + 1, memory_order_relaxed);
72 } else { /* Empty queue. */
74 atomic_store_explicit(&q->bottom, b + 1, memory_order_relaxed);
79 void resize(Deque *q) {
80 Array *a = (Array *) atomic_load_explicit(&q->array, memory_order_relaxed);
81 size_t size=atomic_load_explicit(&a->size, memory_order_relaxed);
82 size_t new_size=size << 1;
83 Array *new_a = (Array *) calloc(1, new_size * sizeof(atomic_int) + sizeof(Array));
84 size_t top=atomic_load_explicit(&q->top, memory_order_relaxed);
85 size_t bottom=atomic_load_explicit(&q->bottom, memory_order_relaxed);
86 atomic_store_explicit(&new_a->size, new_size, memory_order_relaxed);
88 for(i=top; i < bottom; i++) {
90 model_print("resize: new_size == 0\n");
92 model_print("resize: size == 0\n");
93 atomic_store_explicit(&new_a->buffer[i % new_size], atomic_load_explicit(&a->buffer[i % size], memory_order_relaxed), memory_order_relaxed);
95 atomic_store_explicit(&q->array, new_a, memory_order_release);
101 @Interface_define: Push
104 void push(Deque *q, int x) {
105 size_t b = atomic_load_explicit(&q->bottom, memory_order_relaxed);
106 size_t t = atomic_load_explicit(&q->top, memory_order_acquire);
107 Array *a = (Array *) atomic_load_explicit(&q->array, memory_order_relaxed);
108 if (b - t > atomic_load_explicit(&a->size, memory_order_relaxed) - 1) /* Full queue. */ {
110 //Bug in paper...should have next line...
111 a = (Array *) atomic_load_explicit(&q->array, memory_order_relaxed);
113 int size = atomic_load_explicit(&a->size, memory_order_relaxed);
115 model_print("push: size == 0\n");
116 atomic_store_explicit(&a->buffer[b % size], x, memory_order_relaxed);
117 atomic_thread_fence(memory_order_release);
120 @Commit_point_define_check: true
124 atomic_store_explicit(&q->bottom, b + 1, memory_order_relaxed);
129 @Interface_define: Steal
132 int steal(Deque *q) {
133 size_t t = atomic_load_explicit(&q->top, memory_order_acquire);
134 atomic_thread_fence(memory_order_seq_cst);
135 size_t b = atomic_load_explicit(&q->bottom, memory_order_acquire);
138 @Commit_point_define_check: t >= b
144 /* Non-empty queue. */
145 Array *a = (Array *) atomic_load_explicit(&q->array, memory_order_acquire);
146 int size = atomic_load_explicit(&a->size, memory_order_relaxed);
148 model_print("steal: size == 0\n");
149 x = atomic_load_explicit(&a->buffer[t % size], memory_order_relaxed);
150 bool succ = atomic_compare_exchange_strong_explicit(&q->top, &t, t + 1,
151 memory_order_seq_cst, memory_order_relaxed);
154 @Commit_point_define_check: succ == true
161 @Commit_point_define_check: succ == false