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 x = atomic_load_explicit(&a->buffer[b % atomic_load_explicit(&a->size,memory_order_relaxed)], memory_order_relaxed);
41 @Commit_point_define_check: t != b
46 /* Single last element in queue. */
47 bool succ = atomic_compare_exchange_strong_explicit(&q->top, &t, t +
48 1, memory_order_seq_cst, memory_order_relaxed);
51 @Commit_point_define_check: succ == true
58 @Commit_point_define_check: succ == false
66 atomic_store_explicit(&q->bottom, b + 1, memory_order_relaxed);
68 } else { /* Empty queue. */
70 atomic_store_explicit(&q->bottom, b + 1, memory_order_relaxed);
75 void resize(Deque *q) {
76 Array *a = (Array *) atomic_load_explicit(&q->array, memory_order_relaxed);
77 size_t size=atomic_load_explicit(&a->size, memory_order_relaxed);
78 size_t new_size=size << 1;
79 Array *new_a = (Array *) calloc(1, new_size * sizeof(atomic_int) + sizeof(Array));
80 size_t top=atomic_load_explicit(&q->top, memory_order_relaxed);
81 size_t bottom=atomic_load_explicit(&q->bottom, memory_order_relaxed);
82 atomic_store_explicit(&new_a->size, new_size, memory_order_relaxed);
84 for(i=top; i < bottom; i++) {
85 atomic_store_explicit(&new_a->buffer[i % new_size], atomic_load_explicit(&a->buffer[i % size], memory_order_relaxed), memory_order_relaxed);
87 atomic_store_explicit(&q->array, new_a, memory_order_release);
93 @Interface_define: Push
96 void push(Deque *q, int x) {
97 size_t b = atomic_load_explicit(&q->bottom, memory_order_relaxed);
98 size_t t = atomic_load_explicit(&q->top, memory_order_acquire);
99 Array *a = (Array *) atomic_load_explicit(&q->array, memory_order_relaxed);
100 if (b - t > atomic_load_explicit(&a->size, memory_order_relaxed) - 1) /* Full queue. */ {
102 //Bug in paper...should have next line...
103 a = (Array *) atomic_load_explicit(&q->array, memory_order_relaxed);
105 atomic_store_explicit(&a->buffer[b % atomic_load_explicit(&a->size, memory_order_relaxed)], x, memory_order_relaxed);
106 atomic_thread_fence(memory_order_release);
109 @Commit_point_define_check: true
113 atomic_store_explicit(&q->bottom, b + 1, memory_order_relaxed);
118 @Interface_define: Steal
121 int steal(Deque *q) {
122 size_t t = atomic_load_explicit(&q->top, memory_order_acquire);
123 atomic_thread_fence(memory_order_seq_cst);
124 size_t b = atomic_load_explicit(&q->bottom, memory_order_acquire);
127 @Commit_point_define_check: t >= b
133 /* Non-empty queue. */
134 Array *a = (Array *) atomic_load_explicit(&q->array, memory_order_acquire);
135 x = atomic_load_explicit(&a->buffer[t % atomic_load_explicit(&a->size, memory_order_relaxed)], memory_order_relaxed);
136 bool succ = atomic_compare_exchange_strong_explicit(&q->top, &t, t + 1,
137 memory_order_seq_cst, memory_order_relaxed);
140 @Commit_point_define_check: succ == true
147 @Commit_point_define_check: succ == false