Reduce task's context size

Since RTC ans STK timestamps are now different, they don't need to be as big and
be can safely reduce their size to 24 bits to save space

drv/rcc.c

@@ -161,26 +161,27 @@ static void apply_speed_preset(void)
 	//restore sane values
 	apply_default_preset();
 
-	//try enabling HSE, fallback to HSI if HSE fails
+	//enable HSE
 	regs->CR.HSEON = 1;
-	for (uint32_t i=0; i<1000; ++i) {
+	for (uint32_t i=0; i<10000; ++i) {
-		__asm__("nop");
+		__asm("nop");
 	}
 	if (regs->CR.HSERDY == 0x1) {
 		regs->CFGR.PLLSCR = 1;
 	} else {
-		regs->CR.HSEON = 0;
+		apply_default_preset();
+		while (true);
 	}
 
-	//configure PLL, fallback to HSI if PLL fails
+	//configure PLL
 	regs->CFGR.PLLMUL = 0x7; //PLL x9
 	regs->CR.PLLON = 1;
-	for (uint32_t i=0; i<1000; ++i) {
+	for (uint32_t i=0; i<10000; ++i) {
-		__asm__("nop");
+		__asm("nop");
 	}
 	if (regs->CR.PLLRDY != 0x1) {
-		regs->CR.PLLON = 0;
+		apply_default_preset();
-		return; //clock low enough, no need for prescalers
+		while (true);
 	}
 
 	//configure prescalers

srv/debug.c

@@ -18,6 +18,7 @@
 
 static uint32_t write_debug(uint8_t c, void* arg);
 
+#define DEBUG_BAUDRATE 115200
 #define BUFFER_SIZE 162  //(80 char line + \n) * 2
 
 
@@ -34,7 +35,7 @@ void _debug_init(enum UsartPeriph usart, enum GpioPort tx_port,
 {
 	gpio_configure(tx_port, tx_pin, GPIO_MODE_OUTPUT_FAST,
 			GPIO_CONFIG_OUT_ALT_PUSH_PULL);
-	usart_configure(usart, USART_CONFIG_8N1, 1000000);
+	usart_configure(usart, USART_CONFIG_8N1, DEBUG_BAUDRATE);
 	dma_mbuf_configure(&mbuf,usart_configure_tx_dma(usart),
 			DMA_CONFIG_PRIO_LOW, tx_buffer, BUFFER_SIZE);
 

srv/task.c

@@ -47,8 +47,6 @@ static struct Task task_list[MAX_TASK_NB];
 static uint8_t task_nb;
 static volatile bool stk_irq;
 static volatile bool rtc_irq;
-static volatile uint32_t timestamp;
-
 
 //--public functions------------------------------------------------------------
 
@@ -58,9 +56,15 @@ void task_start_scheduler(void)
 
 	rcc_configure_lsi(true);
 	pwr_configure_bkp_write(true);
-	bkp_configure_rtc(1000, BKP_RTC_CLOCK_SRC_LSI, BKP_RTC_IRQ_NONE, nullptr);
+	//may need to be looked into later: basically, the RTC only wakes up the
+	//system 1 tick too late when using pwr_stop(). To fix that, we can use a
+	//tick divided by 2, but I have no idea what the underlying problem is
+	bkp_configure_rtc(500, BKP_RTC_CLOCK_SRC_LSI, BKP_RTC_IRQ_NONE, nullptr);
 	pwr_configure_bkp_write(false);
 	exti_configure(EXTI_LINE_RTC, EXTI_CONFIG_RISING_EDGE, callback_rtc);
+	pwr_configure_bkp_write(true);
+	bkp_set_rtc_alam(1);
+	pwr_configure_bkp_write(false);
 
 	while (true) {
 		uint8_t triggers = stk_irq << 0 | rtc_irq << 1;
@@ -76,20 +80,12 @@ void task_start_scheduler(void)
 			stk_start();
 			pwr_sleep();
 		} else {
-			pwr_configure_bkp_write(true);
-			bkp_set_rtc_alam(1);
-			pwr_configure_bkp_write(false);
 			stk_stop();
-			pwr_sleep();
+			pwr_stop(PWR_WAKEUP_SPEED_SLOW);
 		}
 	}
 }
 
-uint32_t task_current_time(void)
-{
-	return timestamp;
-}
-
 void task_start(TaskFunction function)
 {
 	for (uint8_t i = 0; i < MAX_TASK_NB; ++i) {
@@ -112,7 +108,7 @@ void task_stop(TaskFunction function)
 	for (uint8_t i = 0; i < task_nb; ++i) {
 		if (task_list[i].function == function) {
 			task_list[i].state.count = _TASK_COUNT_CLEANUP & 0x1F;
-			task_list[i].function(&task_list[i].state, timestamp);
+			task_list[i].function(&task_list[i].state);
 			task_list[i].function = nullptr;
 
 			return;
@@ -139,18 +135,14 @@ static bool execute_task(struct Task* restrict task, uint8_t triggers)
 {
 	if (task->function != nullptr) {
 		if (task->state.trigger == TASK_TRIGGER_ANY) {
-			task->function(&task->state, timestamp);
+			task->function(&task->state);
 		} else {
 			if ((task->state.trigger & triggers) != 0) {
 
-				if (task->state.timestamp <= timestamp) {
+				--task->state.timestamp;
-					task->state.timestamp = 0;
-				}
-
 				if ((task->state.timestamp == 0) ||
 						task->state.timeout_mode)  {
-					task->function(&task->state,
+					task->function(&task->state);
-							timestamp);
 				}
 			}
 		}
@@ -164,11 +156,13 @@ static bool execute_task(struct Task* restrict task, uint8_t triggers)
 static void callback_stk(void)
 {
 	stk_irq = true;
-	++timestamp;
 }
 
 static void callback_rtc(void)
 {
 	rtc_irq = true;
-	timestamp = bkp_read_rtc() * 1000;
+	pwr_configure_bkp_write(true);
+	bkp_set_rtc_alam(1);
+	pwr_configure_bkp_write(false);
 }
+

srv/task.h

@@ -47,16 +47,16 @@ enum TaskTrigger {
  * struct
  */
 struct TaskState {
-	uint32_t timestamp;         //timestamp at wich to wakeup the task, if any
+	uint32_t timestamp:24;      //timestamp at wich to wakeup the task, if any
-	uint8_t count:5;            //task counter: active step of task
+	uint32_t count:5;           //task counter: active step of task
 	enum TaskTrigger trigger:2; //triggers on wich to execute the task
-	uint8_t timeout_mode:1;     //whether the timestamp is a timeout or a delay
+	uint32_t timeout_mode:1;    //whether the timestamp is a timeout or a delay
 };
 
 /**
  * Function prototype of tasks
  */
-typedef void(*TaskFunction)(struct TaskState*, uint32_t);
+typedef void(*TaskFunction)(struct TaskState*);
 
 /**
  * Full definition of a task. Contains the function supporting the task as well
@@ -74,8 +74,7 @@ struct Task {
  * Task declaration macro, to be used to declare and define a task instead of a
  * regular function declaration/defintion
  */
-#define TASK(fct_name) void fct_name(struct TaskState* restrict __task_state,  \
+#define TASK(fct_name) void fct_name(struct TaskState* restrict __task_state)
-		uint32_t __task_time)
 
 /**
  * Task entry macro, must be present at the begin of every task. Setup code to
@@ -84,7 +83,6 @@ struct Task {
  */
 #define TASK_ENTRY                                                             \
 	_TASK_COUNT_INIT;                                                          \
-	(void) __task_time;                                                       \
 	switch (__task_state->count) {
 
 /**
@@ -217,7 +215,7 @@ bool task_is_running(TaskFunction task);
 
 #define _TASK_PAUSE(delay_ms, count_val) do {                                  \
 	__task_state->count = count_val;                                           \
-	__task_state->timestamp = __task_time + delay_ms;                          \
+	__task_state->timestamp += delay_ms;                                       \
 	__task_state->trigger = TASK_TRIGGER_STK;                                  \
 	return;                                                                    \
 	case (count_val):                                                          \
@@ -226,7 +224,7 @@ bool task_is_running(TaskFunction task);
 
 #define _TASK_SLEEP(delay_s, count_val) do {                                   \
 	__task_state->count = count_val;                                           \
-	__task_state->timestamp = __task_time + delay_s * 1000;                    \
+	__task_state->timestamp += delay_s;                                        \
 	__task_state->trigger = TASK_TRIGGER_RTC;                                  \
 	return;                                                                    \
 	case (count_val):                                                          \
@@ -245,7 +243,7 @@ bool task_is_running(TaskFunction task);
 
 #define _TASK_PAUSE_UNTIL(cond, delay_ms, count_val) do {                      \
 	__task_state->count = count_val;                                           \
-	__task_state->timestamp = __task_time + delay_ms;                          \
+	__task_state->timestamp += delay_ms;                                       \
 	__task_state->trigger = TASK_TRIGGER_STK;                                  \
 	__task_state->timeout_mode = true;                                         \
 	case (count_val):                                                          \
@@ -253,13 +251,14 @@ bool task_is_running(TaskFunction task);
 			return;                                                            \
 		} else {                                                               \
 			__task_state->timeout_mode = false;                                \
+			__task_state->timestamp = 0;                                       \
 		}                                                                      \
 		/* fall through */                                                     \
 	} while (0)
 
 #define _TASK_SLEEP_UNTIL(cond, delay_s, count_val) do {                       \
 	__task_state->count = count_val;                                           \
-	__task_state->timestamp = __taks_time + delay_s * 1000;                    \
+	__task_state->timestamp += delay_s;                                        \
 	__task_state->trigger = TASK_TRIGGER_RTC;                                  \
 	__task_state->timeout_mode = true;                                         \
 	case (count_val):                                                          \