2 This file is part of PulseAudio.
4 Copyright 2006 Lennart Poettering
6 PulseAudio is free software; you can redistribute it and/or modify
7 it under the terms of the GNU Lesser General Public License as
8 published by the Free Software Foundation; either version 2.1 of the
9 License, or (at your option) any later version.
11 PulseAudio is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with PulseAudio; if not, write to the Free Software
18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
29 #include <pulsecore/atomic.h>
30 #include <pulsecore/log.h>
31 #include <pulsecore/thread.h>
32 #include <pulsecore/macro.h>
33 #include <pulsecore/core-util.h>
34 #include <pulse/xmalloc.h>
38 /* For debugging purposes we can define _Y to put and extra thread
39 * yield between each operation. */
44 #define _Y pa_thread_yield()
46 #define _Y do { } while(0)
51 pa_fdsem *read_fdsem, *write_fdsem;
52 pa_shmasyncq_data *data;
55 static int is_power_of_two(unsigned size) {
56 return !(size & (size - 1));
59 static int reduce(pa_shmasyncq *l, int value) {
60 return value & (unsigned) (l->n_elements - 1);
63 static pa_atomic_t* get_cell(pa_shmasyncq *l, unsigned i) {
64 pa_assert(i < l->data->n_elements);
66 return (pa_atomic_t*) ((uint8*t) l->data + PA_ALIGN(sizeof(pa_shmasyncq_data)) + i * (PA_ALIGN(sizeof(pa_atomic_t)) + PA_ALIGN(element_size)))
69 static void *get_cell_data(pa_atomic_t *a) {
70 return (uint8_t*) a + PA_ALIGN(sizeof(atomic_t));
73 pa_shmasyncq *pa_shmasyncq_new(unsigned n_elements, size_t element_size, void *data, int fd[2]) {
76 pa_assert(n_elements > 0);
77 pa_assert(is_power_of_two(n_elements));
78 pa_assert(element_size > 0);
82 l = pa_xnew(pa_shmasyncq, 1);
85 memset(data, 0, PA_SHMASYNCQ_SIZE(n_elements, element_size));
87 l->data->n_elements = n_elements;
88 l->data->element_size = element_size;
90 if (!(l->read_fdsem = pa_fdsem_new_shm(&d->read_fdsem_data, &fd[0]))) {
95 if (!(l->write_fdsem = pa_fdsem_new(&d->write_fdsem_data, &fd[1]))) {
96 pa_fdsem_free(l->read_fdsem);
104 void pa_shmasyncq_free(pa_shmasyncq *l, pa_free_cb_t free_cb) {
110 while ((p = pa_shmasyncq_pop(l, 0)))
114 pa_fdsem_free(l->read_fdsem);
115 pa_fdsem_free(l->write_fdsem);
119 int pa_shmasyncq_push(pa_shmasyncq*l, void *p, int wait) {
121 pa_atomic_ptr_t *cells;
126 cells = PA_SHMASYNCQ_CELLS(l);
129 idx = reduce(l, l->write_idx);
131 if (!pa_atomic_ptr_cmpxchg(&cells[idx], NULL, p)) {
136 /* pa_log("sleeping on push"); */
139 pa_fdsem_wait(l->read_fdsem);
140 } while (!pa_atomic_ptr_cmpxchg(&cells[idx], NULL, p));
146 pa_fdsem_post(l->write_fdsem);
151 void* pa_shmasyncq_pop(pa_shmasyncq*l, int wait) {
154 pa_atomic_ptr_t *cells;
158 cells = PA_SHMASYNCQ_CELLS(l);
161 idx = reduce(l, l->read_idx);
163 if (!(ret = pa_atomic_ptr_load(&cells[idx]))) {
168 /* pa_log("sleeping on pop"); */
171 pa_fdsem_wait(l->write_fdsem);
172 } while (!(ret = pa_atomic_ptr_load(&cells[idx])));
177 /* Guaranteed to succeed if we only have a single reader */
178 pa_assert_se(pa_atomic_ptr_cmpxchg(&cells[idx], ret, NULL));
183 pa_fdsem_post(l->read_fdsem);
188 int pa_shmasyncq_get_fd(pa_shmasyncq *q) {
191 return pa_fdsem_get(q->write_fdsem);
194 int pa_shmasyncq_before_poll(pa_shmasyncq *l) {
196 pa_atomic_ptr_t *cells;
200 cells = PA_SHMASYNCQ_CELLS(l);
203 idx = reduce(l, l->read_idx);
206 if (pa_atomic_ptr_load(&cells[idx]))
209 if (pa_fdsem_before_poll(l->write_fdsem) >= 0)
216 void pa_shmasyncq_after_poll(pa_shmasyncq *l) {
219 pa_fdsem_after_poll(l->write_fdsem);