fix(flush,tick): use atomics instead of volatile for synchronization (#3965)

src/hal/lv_hal_disp.h

@@ -23,6 +23,11 @@ extern "C" {
 #include "../misc/lv_area.h"
 #include "../misc/lv_ll.h"
 #include "../misc/lv_timer.h"
+#include "../misc/lv_types.h"
+
+#if LV_USE_ATOMICS == 1
+#include <stdatomic.h>
+#endif
 
 /*********************
  *      DEFINES
@@ -47,6 +52,11 @@ struct _lv_disp_t;
 struct _lv_disp_drv_t;
 struct _lv_theme_t;
 
+#if LV_USE_ATOMICS == 1
+#define FLUSHING_TYPE atomic_int
+#else
+#define FLUSHING_TYPE volatile int
+#endif
 /**
  * Structure for holding display buffer information.
  */
@@ -57,13 +67,13 @@ typedef struct _lv_disp_draw_buf_t {
     /*Internal, used by the library*/
     void * buf_act;
     uint32_t size; /*In pixel count*/
-    /*1: flushing is in progress. (It can't be a bit field because when it's cleared from IRQ Read-Modify-Write issue might occur)*/
-    volatile int flushing;
-    /*1: It was the last chunk to flush. (It can't be a bit field because when it's cleared from IRQ Read-Modify-Write issue might occur)*/
-    volatile int flushing_last;
-    volatile uint32_t last_area         : 1; /*1: the last area is being rendered*/
-    volatile uint32_t last_part         : 1; /*1: the last part of the current area is being rendered*/
+    FLUSHING_TYPE flushing;
+    /*It was the last chunk to flush. (It can't be a bit field because when it's cleared from IRQ Read-Modify-Write issue might occur)*/
+    FLUSHING_TYPE flushing_last;
+    uint32_t last_area         : 1; /*1: the last area is being rendered*/
+    uint32_t last_part         : 1; /*1: the last part of the current area is being rendered*/
 } lv_disp_draw_buf_t;
+#undef FLUSHING_TYPE
 
 typedef enum {
     LV_DISP_ROT_NONE = 0,

src/hal/lv_hal_tick.c

@@ -7,6 +7,8 @@
  *      INCLUDES
  *********************/
 #include "lv_hal_tick.h"
+#include "../misc/lv_types.h"
+#include <stdatomic.h>
 #include <stddef.h>
 
 #if LV_TICK_CUSTOM == 1
@@ -29,8 +31,13 @@
  *  STATIC VARIABLES
  **********************/
 #if !LV_TICK_CUSTOM
-    static uint32_t sys_time = 0;
-    static volatile uint8_t tick_irq_flag;
+    #if LV_USE_ATOMICS == 1
+        static _Atomic(uint32_t) sys_time = 0;
+        static atomic_int tick_irq_flag;
+    #else
+        static volatile uint32_t sys_time = 0;
+        static volatile int tick_irq_flag;
+    #endif
 #endif
 
 /**********************

src/misc/lv_types.h

@@ -32,6 +32,15 @@ extern "C" {
 
 #endif
 
+/*Use atomics instead of volatile variables for state which is potentially shared between threads, as long as
+ *the compiler supports it.*/
+#if (defined(__cplusplus) && __cplusplus >= 201103L)\
+    || (__STDC_VERSION__ >= 201112L && !defined(__STDC_NO_ATOMICS__))
+#define LV_USE_ATOMICS 1
+#else
+#define LV_USE_ATOMICS 0
+#endif
+
 /**********************
  *      TYPEDEFS
  **********************/