altos: Optimize FEC encode and decode

Integrate interleaving, CRC and padding within the decode/encode
functions.

Provide for ISR priorities so that the 1120 RX interrupt takes
precedence over the other interrupts or we risk losing bits.

Optimize the viterbi decoder a bit (goes from 10ms per packet to 7ms
per packet).

Signed-off-by: Keith Packard <keithp@keithp.com>

5 files changed, 73 insertions, 34 deletions

diff --git a/src/stm/ao_arch.h b/src/stm/ao_arch.h
index bbd1b3b1..30cd9ea5 100644
--- a/src/stm/ao_arch.h
+++ b/src/stm/ao_arch.h
@@ -25,7 +25,7 @@
  * STM32L definitions and code fragments for AltOS
  */
 
-#define AO_STACK_SIZE	1024
+#define AO_STACK_SIZE	512
 
 #define AO_LED_TYPE	uint16_t
 
@@ -111,14 +111,22 @@ extern const uint16_t ao_serial_number;
 		uint32_t	*sp;					\
 		asm("mov %0,sp" : "=&r" (sp) );				\
 		ao_cur_task->sp = (sp);					\
-		if ((uint8_t *) sp < ao_cur_task->stack)		\
+		if ((uint8_t *) sp < &ao_cur_task->stack[0])		\
 			ao_panic (AO_PANIC_STACK);			\
 	} while (0)
 
-#define ao_arch_isr_stack()	/* nothing */
+#if 0
+#define ao_arch_isr_stack() do {				\
+		uint32_t	*sp = (uint32_t *) 0x20004000;	\
+		asm("mov %0,sp" : "=&r" (sp) );			\
+	} while (0)
+#else
+#define ao_arch_isr_stack()
+#endif
+
 
 #define ao_arch_cpu_idle() do {			\
-		asm("wfi");			\
+		asm("wfi");		\
 	} while (0)
 
 #define ao_arch_restore_stack() do { \
@@ -173,6 +181,11 @@ extern const uint16_t ao_serial_number;
 #define AO_TIM91011_CLK		(2 * AO_PCLK2)
 #endif
 
+#define AO_STM_NVIC_HIGH_PRIORITY	4
+#define AO_STM_NVIC_CLOCK_PRIORITY	6
+#define AO_STM_NVIC_MED_PRIORITY	8
+#define AO_STM_NVIC_LOW_PRIORITY	10
+
 void ao_lcd_stm_init(void);
 
 void ao_lcd_font_init(void);
@@ -215,7 +228,7 @@ ao_serial3_pollchar(void);
 void
 ao_serial3_set_speed(uint8_t speed);
 
-extern uint32_t	ao_radio_cal;
+extern const uint32_t	ao_radio_cal;
 
 void
 ao_adc_init();
diff --git a/src/stm/ao_exti.h b/src/stm/ao_exti.h
index 87a072e7..b579ad9f 100644
--- a/src/stm/ao_exti.h
+++ b/src/stm/ao_exti.h
@@ -22,6 +22,9 @@
 #define AO_EXTI_MODE_FALLING	2
 #define AO_EXTI_MODE_PULL_UP	4
 #define AO_EXTI_MODE_PULL_DOWN	8
+#define AO_EXTI_PRIORITY_LOW	16
+#define AO_EXTI_PRIORITY_MED	0
+#define AO_EXTI_PRIORITY_HIGH	32
 
 void
 ao_exti_setup(struct stm_gpio *gpio, uint8_t pin, uint8_t mode, void (*callback)());
diff --git a/src/stm/ao_exti_stm.c b/src/stm/ao_exti_stm.c
index 683a91b3..d54e6ee6 100644
--- a/src/stm/ao_exti_stm.c
+++ b/src/stm/ao_exti_stm.c
@@ -20,37 +20,50 @@
 
 static void	(*ao_exti_callback[16])(void);
 
-static void
-ao_exti_isr(void) {
-	uint32_t	pending = stm_exti.pr;
-	uint8_t		pin;
+uint32_t	ao_last_exti;
+
+static void ao_exti_one_isr(uint8_t pin) {
+	uint32_t	pending = (ao_last_exti = stm_exti.pr) & (1 << pin);
 
-	/* Clear pending interrupts */
 	stm_exti.pr = pending;
-	for (pin = 0; pin < 16 && pending; pin++) {
-		uint32_t	mask = (1 << pin);
+	if (pending && ao_exti_callback[pin])
+		(*ao_exti_callback[pin])();
+}
 
-		if (pending & mask) {
-			pending &= ~mask;
-			if (ao_exti_callback[pin])
-				(*ao_exti_callback[pin])();
-		}
+static void ao_exti_range_isr(uint8_t first, uint8_t last, uint16_t mask) {
+	uint16_t	pending = (ao_last_exti = stm_exti.pr) & mask;
+	uint8_t		pin;
+	static uint16_t	last_mask;
+	static uint8_t	last_pin;
+
+	if (pending == last_mask) {
+		stm_exti.pr = last_mask;
+		(*ao_exti_callback[last_pin])();
+		return;
 	}
+	stm_exti.pr = pending;
+	for (pin = first; pin <= last; pin++)
+		if ((pending & ((uint32_t) 1 << pin)) && ao_exti_callback[pin]) {
+			last_mask = (1 << pin);
+			last_pin = pin;
+			(*ao_exti_callback[pin])();
+		}
 }
 
-void stm_exti0_isr(void) { ao_exti_isr(); }
-void stm_exti1_isr(void) { ao_exti_isr(); }
-void stm_exti2_isr(void) { ao_exti_isr(); }
-void stm_exti3_isr(void) { ao_exti_isr(); }
-void stm_exti4_isr(void) { ao_exti_isr(); }
-void stm_exti9_5_isr(void) { ao_exti_isr(); }
-void stm_exti15_10_isr(void) { ao_exti_isr(); }
+void stm_exti0_isr(void) { ao_exti_one_isr(0); }
+void stm_exti1_isr(void) { ao_exti_one_isr(1); }
+void stm_exti2_isr(void) { ao_exti_one_isr(2); }
+void stm_exti3_isr(void) { ao_exti_one_isr(3); }
+void stm_exti4_isr(void) { ao_exti_one_isr(4); }
+void stm_exti9_5_isr(void) { ao_exti_range_isr(5, 9, 0x3e0); }
+void stm_exti15_10_isr(void) { ao_exti_range_isr(10, 15, 0xfc00); }
 
 void
 ao_exti_setup (struct stm_gpio *gpio, uint8_t pin, uint8_t mode, void (*callback)(void)) {
 	uint32_t	mask = 1 << pin;
 	uint32_t	pupdr;
 	uint8_t		irq;
+	uint8_t		prio;
 
 	ao_exti_callback[pin] = callback;
 
@@ -90,7 +103,15 @@ ao_exti_setup (struct stm_gpio *gpio, uint8_t pin, uint8_t mode, void (*callback
 		irq = STM_ISR_EXTI9_5_POS;
 	else
 		irq = STM_ISR_EXTI15_10_POS;
-	stm_nvic_set_priority(irq, 10);
+
+	/* Set priority */
+	prio = AO_STM_NVIC_MED_PRIORITY;
+	if (mode & AO_EXTI_PRIORITY_LOW)
+		prio = AO_STM_NVIC_LOW_PRIORITY;
+	else if (mode & AO_EXTI_PRIORITY_HIGH)
+		prio = AO_STM_NVIC_HIGH_PRIORITY;
+
+	stm_nvic_set_priority(irq, prio);
 	stm_nvic_set_enable(irq);
 }
 
@@ -116,10 +137,10 @@ ao_exti_disable(struct stm_gpio *gpio, uint8_t pin) {
 void
 ao_exti_init(void)
 {
-	stm_nvic_set_priority(STM_ISR_EXTI1_POS, 10);
-	stm_nvic_set_priority(STM_ISR_EXTI2_POS, 10);
-	stm_nvic_set_priority(STM_ISR_EXTI3_POS, 10);
-	stm_nvic_set_priority(STM_ISR_EXTI4_POS, 10);
-	stm_nvic_set_priority(STM_ISR_EXTI9_5_POS, 10);
-	stm_nvic_set_priority(STM_ISR_EXTI15_10_POS, 10);
+	stm_nvic_set_priority(STM_ISR_EXTI1_POS, AO_STM_NVIC_MED_PRIORITY);
+	stm_nvic_set_priority(STM_ISR_EXTI2_POS, AO_STM_NVIC_MED_PRIORITY);
+	stm_nvic_set_priority(STM_ISR_EXTI3_POS, AO_STM_NVIC_MED_PRIORITY);
+	stm_nvic_set_priority(STM_ISR_EXTI4_POS, AO_STM_NVIC_MED_PRIORITY);
+	stm_nvic_set_priority(STM_ISR_EXTI9_5_POS, AO_STM_NVIC_MED_PRIORITY);
+	stm_nvic_set_priority(STM_ISR_EXTI15_10_POS, AO_STM_NVIC_MED_PRIORITY);
 }
diff --git a/src/stm/ao_spi_stm.c b/src/stm/ao_spi_stm.c
index d3378648..26227086 100644
--- a/src/stm/ao_spi_stm.c
+++ b/src/stm/ao_spi_stm.c
@@ -23,7 +23,8 @@ struct ao_spi_stm_info {
 	struct stm_spi *stm_spi;
 };
 
-uint8_t	ao_spi_mutex[STM_NUM_SPI];
+uint8_t		ao_spi_mutex[STM_NUM_SPI];
+uint16_t	ao_spi_speed[STM_NUM_SPI];
 
 static const struct ao_spi_stm_info ao_spi_stm_info[STM_NUM_SPI] = {
 	{
@@ -282,7 +283,7 @@ ao_spi_get(uint8_t spi_index)
 			(1 << STM_SPI_CR1_SSI) |			/*  ... */
 			(0 << STM_SPI_CR1_LSBFIRST) |			/* Big endian */
 			(1 << STM_SPI_CR1_SPE) |			/* Enable SPI unit */
-			(STM_SPI_CR1_BR_PCLK_16 << STM_SPI_CR1_BR) |	/* baud rate to pclk/4 */
+			(ao_spi_speed[spi_index] << STM_SPI_CR1_BR) |	/* baud rate to pclk/4 */
 			(1 << STM_SPI_CR1_MSTR) |
 			(0 << STM_SPI_CR1_CPOL) |			/* Format 0 */
 			(0 << STM_SPI_CR1_CPHA));
@@ -310,6 +311,7 @@ ao_spi_channel_init(uint8_t spi_index)
 			(0 << STM_SPI_CR2_SSOE) |
 			(0 << STM_SPI_CR2_TXDMAEN) |
 			(0 << STM_SPI_CR2_RXDMAEN));
+	ao_spi_speed[spi_index] = AO_SPI_SPEED_FAST;
 }
 
 void
diff --git a/src/stm/ao_timer.c b/src/stm/ao_timer.c
index 0c44f352..936dc881 100644
--- a/src/stm/ao_timer.c
+++ b/src/stm/ao_timer.c
@@ -87,7 +87,7 @@ void
 ao_timer_init(void)
 {
 	stm_nvic_set_enable(STM_ISR_TIM6_POS);
-	stm_nvic_set_priority(STM_ISR_TIM6_POS, 1);
+	stm_nvic_set_priority(STM_ISR_TIM6_POS, AO_STM_NVIC_CLOCK_PRIORITY);
 
 	/* Turn on timer 6 */
 	stm_rcc.apb1enr |= (1 << STM_RCC_APB1ENR_TIM6EN);