pbio/os: Prototype simpler and unified async OS.

lib/pbio/drv/charger/charger_mp2639a.c

@@ -282,7 +282,7 @@ pbio_error_t pbdrv_charger_mp2639a_process_thread(pbio_os_state_t *state, void *
 
 void pbdrv_charger_init(void) {
     pbdrv_init_busy_up();
-    pbio_os_start_process(&pbdrv_charger_mp2639a_process, pbdrv_charger_mp2639a_process_thread, NULL);
+    pbio_os_process_start(&pbdrv_charger_mp2639a_process, pbdrv_charger_mp2639a_process_thread, NULL);
 }
 
 #endif // PBDRV_CONFIG_CHARGER_MP2639A

lib/pbio/include/pbio/os.h

@@ -166,6 +166,19 @@ struct _pbio_os_process_t {
         }                                        \
     } while (0)
 
+/**
+ * Yields the protothread until the specified condition is true.
+ *
+ * @param [in]  state     Protothread state.
+ * @param [in]  condition The condition.
+ */
+#define AWAIT_UNTIL(state, condition)            \
+    do {                                         \
+        PB_LC_SET(state);                        \
+        if (!(condition)) {                      \
+            return PBIO_ERROR_AGAIN;             \
+        }                                        \
+    } while (0)
 
 #define AWAIT(state, child, statement)          \
     do {                                        \
@@ -176,6 +189,16 @@ struct _pbio_os_process_t {
         }                                       \
     } while (0)
 
+#define AWAIT_RACE(state, child1, child2, statement1, statement2)                    \
+    do {                                                                             \
+        ASYNC_INIT((child1));                                                        \
+        ASYNC_INIT((child2));                                                        \
+        PB_LC_SET(state);                                                            \
+        if ((statement1) == PBIO_ERROR_AGAIN && (statement2) == PBIO_ERROR_AGAIN) {  \
+            return PBIO_ERROR_AGAIN;                                                 \
+        }                                                                            \
+    } while (0)
+
 #define AWAIT_MS(state, timer, duration)        \
     do {                                        \
         pbio_os_timer_set(timer, duration);     \
@@ -191,7 +214,11 @@ void pbio_os_run_while_idle(void);
 
 void pbio_os_request_poll(void);
 
-void pbio_os_start_process(pbio_os_process_t *process, pbio_os_process_func_t func, void *context);
+pbio_error_t pbio_port_process_none_thread(pbio_os_state_t *state, void *context);
+
+void pbio_os_process_start(pbio_os_process_t *process, pbio_os_process_func_t func, void *context);
+
+void pbio_os_process_reset(pbio_os_process_t *process, pbio_os_process_func_t func);
 
 /**
  * Disables interrupts and returns the previous interrupt state.

lib/pbio/src/os.c

@@ -47,15 +47,23 @@ void pbio_os_request_poll(void) {
 static pbio_os_process_t *process_list = NULL;
 
 /**
- * Starts a process.
+ * Placeholder thread that does nothing.
  *
- * NB: Processes can be started only once. They cannot be restarted.
+ * @param [in] state The protothread state.
+ * @param [in] context The context.
+ */
+pbio_error_t pbio_port_process_none_thread(pbio_os_state_t *state, void *context) {
+    return PBIO_ERROR_AGAIN;
+}
+
+/**
+ * Adds a process to the list of processes to run and starts it soon.
  *
  * @param process   The process to start.
  * @param func      The process thread function.
  * @param context   The context to pass to the process.
  */
-void pbio_os_start_process(pbio_os_process_t *process, pbio_os_process_func_t func, void *context) {
+void pbio_os_process_start(pbio_os_process_t *process, pbio_os_process_func_t func, void *context) {
 
     // Add the new process to the end of the list.
     pbio_os_process_t *last = process_list;
@@ -69,11 +77,27 @@ void pbio_os_start_process(pbio_os_process_t *process, pbio_os_process_func_t fu
     }
 
     // Initialize the process.
-    process->func = func;
-    process->context = context;
     process->next = NULL;
+    process->context = context;
+
+    pbio_os_process_reset(process, func);
+}
+
+/**
+ * Resets an existing process to the initial state with a new function and context.
+ *
+ * @param process   The process to start.
+ * @param func      The process thread function. Choose NULL if it does not need changing.
+ */
+void pbio_os_process_reset(pbio_os_process_t *process, pbio_os_process_func_t func) {
     process->err = PBIO_ERROR_AGAIN;
     process->state = 0;
+    if (func) {
+        process->func = func;
+    }
+
+    // Request a poll to start the process soon, running to its first yield.
+    pbio_os_request_poll();
 }
 
 /**