diff options
Diffstat (limited to 'task.c')
| -rw-r--r-- | task.c | 19 |
1 files changed, 17 insertions, 2 deletions
@@ -108,14 +108,13 @@ tcb_t *task_add(char *name, funcp_t func, void *cookie, void *stack, size_t stac if (tail == NULL) { /* Empty list; initialize it to this task. */ t->next = t; - tail = t; } else { /* Otherwise insert at the end of the list. */ t->next = tail->next; tail->next = t; - tail = t; } + tail = t; return t; } @@ -124,6 +123,11 @@ tcb_t *task_add(char *name, funcp_t func, void *cookie, void *stack, size_t stac * * This function is called repeatedly when the system is idle (there are * no runnable tasks). + * + * The idle function should NOT call task_delay or HAL_Delay, because that + * will cause fatal recursion. We could add a recursion guard to + * task_yield, but we're not currently using the idle hook, and I'm + * thinking about removing it entirely. */ static void default_idle_hook(void) { } static funcp_t idle_hook = default_idle_hook; @@ -170,6 +174,12 @@ void task_yield(void) { tcb_t *next; + /* If there are no defined tasks, exit immediately so we don't get + * caught in the idle loop. + */ + if (tail == NULL) + return; + /* Find the next runnable task. Loop if every task is waiting. */ while (1) { next = next_task(); @@ -326,7 +336,12 @@ void task_delay(uint32_t delay) while ((HAL_GetTick() - tickstart) < delay) task_yield(); } +void HAL_Delay(uint32_t delay) __attribute__((alias("task_delay"))); +/* Simple mutex-like locks. A real mutex would require the unlocker to be + * the current owner, but then we have to define and return errors, when + * all we want at the moment is simple mutual exclusion. + */ void task_mutex_lock(task_mutex_t *mutex) { while (mutex->locked) |