mirror of
https://gitlab.freedesktop.org/pulseaudio/pulseaudio.git
synced 2025-11-02 09:01:46 -05:00
d806b19714
commands used for this (executed from the pulseaudio/src directory):
find . -regex '\(.*\.[hc]\|.*\.cc\|.*\.m4\)' -not -name 'macro.h' \
-a -not -name 'reserve.[ch]' -a -not -name 'reserve-monitor.[ch]' \
-a -not -name 'glib-mainloop.c' -a -not -name 'gkt-test.c' \
-a -not -name 'glib-mainloop.c' -a -not -name 'gkt-test.c' \
-a -not -name 'poll-win32.c' -a -not -name 'thread-win32.c' \
-a -not -name 'dllmain.c' -a -not -name 'gconf-helper.c' \
-exec sed -i -e 's/\bpa_bool_t\b/bool/g' \
-e 's/\bTRUE\b/true/g' -e 's/\bFALSE\b/false/g' {} \;
and:
sed -i -e '181,194!s/\bpa_bool_t\b/bool/' \
-e '181,194!s/\bTRUE\b/true/' -e \
'181,194!s/\bFALSE\b/false/' pulsecore/macro.h
137 lines
3.1 KiB
C
137 lines
3.1 KiB
C
/***
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This file is part of PulseAudio.
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Copyright 2009 Lennart Poettering
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PulseAudio is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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PulseAudio is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with PulseAudio; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
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USA.
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***/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <pulse/xmalloc.h>
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#include <pulsecore/semaphore.h>
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#include <pulsecore/macro.h>
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#include <pulsecore/mutex.h>
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#include "aupdate.h"
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#define MSB (1U << (sizeof(unsigned)*8U-1))
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#define WHICH(n) (!!((n) & MSB))
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#define COUNTER(n) ((n) & ~MSB)
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struct pa_aupdate {
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pa_atomic_t read_lock;
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pa_mutex *write_lock;
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pa_semaphore *semaphore;
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bool swapped;
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};
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pa_aupdate *pa_aupdate_new(void) {
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pa_aupdate *a;
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a = pa_xnew(pa_aupdate, 1);
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pa_atomic_store(&a->read_lock, 0);
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a->write_lock = pa_mutex_new(false, false);
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a->semaphore = pa_semaphore_new(0);
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return a;
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}
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void pa_aupdate_free(pa_aupdate *a) {
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pa_assert(a);
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pa_mutex_free(a->write_lock);
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pa_semaphore_free(a->semaphore);
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pa_xfree(a);
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}
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unsigned pa_aupdate_read_begin(pa_aupdate *a) {
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unsigned n;
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pa_assert(a);
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/* Increase the lock counter */
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n = (unsigned) pa_atomic_inc(&a->read_lock);
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/* When n is 0 we have about 2^31 threads running that all try to
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* access the data at the same time, oh my! */
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pa_assert(COUNTER(n)+1 > 0);
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/* The uppermost bit tells us which data to look at */
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return WHICH(n);
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}
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void pa_aupdate_read_end(pa_aupdate *a) {
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unsigned n;
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pa_assert(a);
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/* Decrease the lock counter */
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n = (unsigned) pa_atomic_dec(&a->read_lock);
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/* Make sure the counter was valid */
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pa_assert(COUNTER(n) > 0);
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/* Post the semaphore */
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pa_semaphore_post(a->semaphore);
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}
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unsigned pa_aupdate_write_begin(pa_aupdate *a) {
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unsigned n;
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pa_assert(a);
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pa_mutex_lock(a->write_lock);
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n = (unsigned) pa_atomic_load(&a->read_lock);
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a->swapped = false;
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return !WHICH(n);
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}
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unsigned pa_aupdate_write_swap(pa_aupdate *a) {
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unsigned n;
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pa_assert(a);
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for (;;) {
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n = (unsigned) pa_atomic_load(&a->read_lock);
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/* If the read counter is > 0 wait; if it is 0 try to swap the lists */
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if (COUNTER(n) > 0)
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pa_semaphore_wait(a->semaphore);
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else if (pa_atomic_cmpxchg(&a->read_lock, (int) n, (int) (n ^ MSB)))
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break;
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}
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a->swapped = true;
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return WHICH(n);
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}
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void pa_aupdate_write_end(pa_aupdate *a) {
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pa_assert(a);
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if (!a->swapped)
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pa_aupdate_write_swap(a);
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pa_mutex_unlock(a->write_lock);
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}
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