Implemented sleep and usleep syscalls.

Signed-off-by: Yilin Sun <imi415@imi.moe>

README.md

@@ -19,4 +19,12 @@ led_red.toggle # Toggle output
 ```ruby
 ana_bg = Machine::ADC.new(52) # BandGap
 ana_bg.value
+```
+
+```ruby
+1000.times do |_|
+    puts "[#{Time.now}] BandGap voltage: #{'%.2f' % (ana_bg.value.to_f / 1000.0)}mV"
+    led_red.toggle
+    usleep(100 * 1000)
+end
 ```

lib/mruby

@@ -1 +1 @@
-Subproject commit 6be5185d38c88b22a9681f4937d47d568651ab73
+Subproject commit 309be9522ba70fc1371ea50b3033b49f4428a01f

src/app_syscalls.c

@@ -300,4 +300,14 @@ int _kill(int pid, int sig) {
 
 int _lseek(int file, int offset, int whence) {
     return 0;
+}
+
+unsigned int sleep(unsigned int sec) {
+    vTaskDelay(pdMS_TO_TICKS(sec * 1000));
+    return 0;
+}
+
+int usleep(useconds_t us) {
+    vTaskDelay(pdMS_TO_TICKS(us / 1000));
+    return 0;
 }

src/mrb_machine_impl/mrb_machine_adc_impl.c

@@ -77,6 +77,7 @@ static void mrb_machine_adc_impl_init_peripheral(void) {
     LPADC_DoAutoCalibration(ADC0);
 
     NVIC_SetPriority(ADC0_IRQn, 5);
+    EnableIRQ(ADC0_IRQn);
 }
 
 int mrb_machine_adc_impl_config(uint32_t channel) {
@@ -143,8 +144,6 @@ int mrb_machine_adc_impl_read(uint32_t channel) {
     }
 
     LPADC_EnableInterrupts(ADC0, kLPADC_FIFO0WatermarkInterruptEnable);
-    EnableIRQ(ADC0_IRQn);
-
     LPADC_DoSoftwareTrigger(ADC0, 1U);
 
     if (xSemaphoreTake(s_adc_semaphore, pdMS_TO_TICKS(500)) != pdTRUE) {
@@ -169,11 +168,15 @@ int mrb_machine_adc_impl_read(uint32_t channel) {
 void ADC0_IRQHandler(void) {
     BaseType_t higher_priority_woken = pdFALSE;
 
-    DisableIRQ(ADC0_IRQn);
+    uint32_t flags = LPADC_GetStatusFlags(ADC0);
+    LPADC_ClearStatusFlags(ADC0, flags);
 
-    xSemaphoreGiveFromISR(s_adc_semaphore, &higher_priority_woken);
+    if (flags & kLPADC_ResultFIFO0ReadyFlag) {
+        LPADC_DisableInterrupts(ADC0, kLPADC_FIFO0WatermarkInterruptEnable);
+        xSemaphoreGiveFromISR(s_adc_semaphore, &higher_priority_woken);
 
-    if (higher_priority_woken) {
-        portYIELD_FROM_ISR(higher_priority_woken);
+        if (higher_priority_woken) {
+            portYIELD_FROM_ISR(higher_priority_woken);
+        }
     }
 }