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);
39 x = atomic_load_explicit(&a->buffer[b % size], memory_order_relaxed);
42 @Commit_point_define_check: t != b
47 /* Single last element in queue. */
48 bool succ = atomic_compare_exchange_strong_explicit(&q->top, &t, t +
49 1, memory_order_seq_cst, memory_order_relaxed);
52 @Commit_point_define_check: succ
60 atomic_store_explicit(&q->bottom, b + 1, memory_order_relaxed);
62 } else { /* Empty queue. */
64 atomic_store_explicit(&q->bottom, b + 1, memory_order_relaxed);
69 void resize(Deque *q) {
70 Array *a = (Array *) atomic_load_explicit(&q->array, memory_order_relaxed);
71 size_t size=atomic_load_explicit(&a->size, memory_order_relaxed);
72 size_t new_size=size << 1;
73 Array *new_a = (Array *) calloc(1, new_size * sizeof(atomic_int) + sizeof(Array));
74 size_t top=atomic_load_explicit(&q->top, memory_order_relaxed);
75 size_t bottom=atomic_load_explicit(&q->bottom, memory_order_relaxed);
76 atomic_store_explicit(&new_a->size, new_size, memory_order_relaxed);
78 for(i=top; i < bottom; i++) {
79 atomic_store_explicit(&new_a->buffer[i % new_size], atomic_load_explicit(&a->buffer[i % size], memory_order_relaxed), memory_order_relaxed);
81 atomic_store_explicit(&q->array, new_a, memory_order_release);
87 @Interface_define: Push
90 void push(Deque *q, int x) {
91 size_t b = atomic_load_explicit(&q->bottom, memory_order_relaxed);
92 size_t t = atomic_load_explicit(&q->top, memory_order_acquire);
93 Array *a = (Array *) atomic_load_explicit(&q->array, memory_order_relaxed);
94 if (b - t > atomic_load_explicit(&a->size, memory_order_relaxed) - 1) /* Full queue. */ {
96 //Bug in paper...should have next line...
97 a = (Array *) atomic_load_explicit(&q->array, memory_order_relaxed);
99 int size = atomic_load_explicit(&a->size, memory_order_relaxed);
100 atomic_store_explicit(&a->buffer[b % size], x, memory_order_relaxed);
103 @Commit_point_define_check: true
107 atomic_thread_fence(memory_order_release);
109 atomic_store_explicit(&q->bottom, b + 1, memory_order_relaxed);
115 @Interface_define: Steal
118 int steal(Deque *q) {
119 size_t t = atomic_load_explicit(&q->top, memory_order_acquire);
120 atomic_thread_fence(memory_order_seq_cst);
121 size_t b = atomic_load_explicit(&q->bottom, memory_order_acquire);
124 @Commit_point_define_check: t >= b
130 /* Non-empty queue. */
131 Array *a = (Array *) atomic_load_explicit(&q->array, memory_order_acquire);
132 int size = atomic_load_explicit(&a->size, memory_order_relaxed);
133 x = atomic_load_explicit(&a->buffer[t % size], memory_order_relaxed);
136 @Potential_commit_point_define: true
137 @Label: Potential_Steal
141 bool succ = atomic_compare_exchange_strong_explicit(&q->top, &t, t + 1,
142 memory_order_seq_cst, memory_order_relaxed);
145 @Commit_point_define_check: !succ
152 @Commit_point_define: succ
153 @Potential_commit_point_label: Potential_Steal