Replace SDL_Atomic by stdatomic from C11

There is no reason to use SDL atomics.

app/src/fps_counter.c

@@ -23,7 +23,7 @@ fps_counter_init(struct fps_counter *counter) {
     }
 
     counter->thread = NULL;
-    SDL_AtomicSet(&counter->started, 0);
+    atomic_init(&counter->started, 0);
     // no need to initialize the other fields, they are unused until started
 
     return true;
@@ -35,6 +35,16 @@ fps_counter_destroy(struct fps_counter *counter) {
     SDL_DestroyMutex(counter->mutex);
 }
 
+static inline bool
+is_started(struct fps_counter *counter) {
+    return atomic_load_explicit(&counter->started, memory_order_acquire);
+}
+
+static inline void
+set_started(struct fps_counter *counter, bool started) {
+    atomic_store_explicit(&counter->started, started, memory_order_release);
+}
+
 // must be called with mutex locked
 static void
 display_fps(struct fps_counter *counter) {
@@ -70,10 +80,10 @@ run_fps_counter(void *data) {
 
     mutex_lock(counter->mutex);
     while (!counter->interrupted) {
-        while (!counter->interrupted && !SDL_AtomicGet(&counter->started)) {
+        while (!counter->interrupted && !is_started(counter)) {
             cond_wait(counter->state_cond, counter->mutex);
         }
-        while (!counter->interrupted && SDL_AtomicGet(&counter->started)) {
+        while (!counter->interrupted && is_started(counter)) {
             uint32_t now = SDL_GetTicks();
             check_interval_expired(counter, now);
 
@@ -96,7 +106,7 @@ fps_counter_start(struct fps_counter *counter) {
     counter->nr_skipped = 0;
     mutex_unlock(counter->mutex);
 
-    SDL_AtomicSet(&counter->started, 1);
+    set_started(counter, true);
     cond_signal(counter->state_cond);
 
     // counter->thread is always accessed from the same thread, no need to lock
@@ -114,13 +124,13 @@ fps_counter_start(struct fps_counter *counter) {
 
 void
 fps_counter_stop(struct fps_counter *counter) {
-    SDL_AtomicSet(&counter->started, 0);
+    set_started(counter, false);
     cond_signal(counter->state_cond);
 }
 
 bool
 fps_counter_is_started(struct fps_counter *counter) {
-    return SDL_AtomicGet(&counter->started);
+    return is_started(counter);
 }
 
 void
@@ -145,7 +155,7 @@ fps_counter_join(struct fps_counter *counter) {
 
 void
 fps_counter_add_rendered_frame(struct fps_counter *counter) {
-    if (!SDL_AtomicGet(&counter->started)) {
+    if (!is_started(counter)) {
         return;
     }
 
@@ -158,7 +168,7 @@ fps_counter_add_rendered_frame(struct fps_counter *counter) {
 
 void
 fps_counter_add_skipped_frame(struct fps_counter *counter) {
-    if (!SDL_AtomicGet(&counter->started)) {
+    if (!is_started(counter)) {
         return;
     }
 

app/src/fps_counter.h

@@ -1,9 +1,9 @@
 #ifndef FPSCOUNTER_H
 #define FPSCOUNTER_H
 
+#include <stdatomic.h>
 #include <stdbool.h>
 #include <stdint.h>
-#include <SDL2/SDL_atomic.h>
 #include <SDL2/SDL_mutex.h>
 #include <SDL2/SDL_thread.h>
 
@@ -16,7 +16,7 @@ struct fps_counter {
 
     // atomic so that we can check without locking the mutex
     // if the FPS counter is disabled, we don't want to lock unnecessarily
-    SDL_atomic_t started;
+    atomic_bool started;
 
     // the following fields are protected by the mutex
     bool interrupted;

app/src/server.c

@@ -338,7 +338,7 @@ run_wait_server(void *data) {
     // no need for synchronization, server_socket is initialized before this
     // thread was created
     if (server->server_socket != INVALID_SOCKET
-            && SDL_AtomicCAS(&server->server_socket_closed, 0, 1)) {
+            && !atomic_flag_test_and_set(&server->server_socket_closed)) {
         // On Linux, accept() is unblocked by shutdown(), but on Windows, it is
         // unblocked by closesocket(). Therefore, call both (close_socket()).
         close_socket(server->server_socket);
@@ -393,8 +393,11 @@ server_start(struct server *server, const char *serial,
 
 error2:
     if (!server->tunnel_forward) {
-        // the wait server thread is not started, SDL_AtomicSet() is sufficient
-        SDL_AtomicSet(&server->server_socket_closed, 1);
+        bool was_closed =
+            atomic_flag_test_and_set(&server->server_socket_closed);
+        // the thread is not started, the flag could not be already set
+        assert(!was_closed);
+        (void) was_closed;
         close_socket(server->server_socket);
     }
     disable_tunnel(server);
@@ -418,7 +421,7 @@ server_connect_to(struct server *server) {
         }
 
         // we don't need the server socket anymore
-        if (SDL_AtomicCAS(&server->server_socket_closed, 0, 1)) {
+        if (!atomic_flag_test_and_set(&server->server_socket_closed)) {
             // close it from here
             close_socket(server->server_socket);
             // otherwise, it is closed by run_wait_server()
@@ -450,7 +453,7 @@ server_connect_to(struct server *server) {
 void
 server_stop(struct server *server) {
     if (server->server_socket != INVALID_SOCKET
-            && SDL_AtomicCAS(&server->server_socket_closed, 0, 1)) {
+            && !atomic_flag_test_and_set(&server->server_socket_closed)) {
         close_socket(server->server_socket);
     }
     if (server->video_socket != INVALID_SOCKET) {

app/src/server.h

@@ -1,9 +1,9 @@
 #ifndef SERVER_H
 #define SERVER_H
 
+#include <stdatomic.h>
 #include <stdbool.h>
 #include <stdint.h>
-#include <SDL2/SDL_atomic.h>
 #include <SDL2/SDL_thread.h>
 
 #include "config.h"
@@ -15,7 +15,7 @@ struct server {
     char *serial;
     process_t process;
     SDL_Thread *wait_server_thread;
-    SDL_atomic_t server_socket_closed;
+    atomic_flag server_socket_closed;
     socket_t server_socket; // only used if !tunnel_forward
     socket_t video_socket;
     socket_t control_socket;
@@ -29,7 +29,7 @@ struct server {
     .serial = NULL, \
     .process = PROCESS_NONE, \
     .wait_server_thread = NULL, \
-    .server_socket_closed = {0}, \
+    .server_socket_closed = ATOMIC_FLAG_INIT, \
     .server_socket = INVALID_SOCKET, \
     .video_socket = INVALID_SOCKET, \
     .control_socket = INVALID_SOCKET, \