Fix support for NRF52

lib/schedule.c

@@ -234,6 +234,7 @@ trigger_handle_t lf_schedule_trigger(environment_t* env, trigger_t* trigger, int
     // If the event is early, see which policy applies.
     if (earliest_time > intended_tag.time) {
       LF_PRINT_DEBUG("Event is early.");
+      event_t *dummy, *found;
       switch (trigger->policy) {
       case drop:
         LF_PRINT_DEBUG("Policy is drop. Dropping the event.");
@@ -247,10 +248,10 @@ trigger_handle_t lf_schedule_trigger(environment_t* env, trigger_t* trigger, int
         // If the event with the previous tag is still on the event
         // queue, then replace the token.  To find this event, we have
         // to construct a dummy event_t struct.
-        event_t* dummy = lf_get_new_event(env);
+        dummy = lf_get_new_event(env);
         dummy->trigger = trigger;
         dummy->base.tag = trigger->last_tag;
-        event_t* found = (event_t*)pqueue_tag_find_equal_same_tag(env->event_q, (pqueue_tag_element_t*)dummy);
+        found = (event_t*)pqueue_tag_find_equal_same_tag(env->event_q, (pqueue_tag_element_t*)dummy);
 
         if (found != NULL) {
           // Recycle the existing token and the new event

low_level_platform/api/CMakeLists.txt

@@ -3,7 +3,7 @@ target_include_directories(lf-low-level-platform-api INTERFACE ${CMAKE_CURRENT_L
 add_library(lf::low-level-platform-api ALIAS lf-low-level-platform-api)
 target_link_libraries(lf-low-level-platform-api INTERFACE lf::tag-api)
 
-if(${CMAKE_SYSTEM_NAME} STREQUAL "Nrf52")
+if(${CMAKE_SYSTEM_NAME} STREQUAL "nRF52")
     target_compile_definitions(lf-low-level-platform-api INTERFACE PLATFORM_NRF52)
 elseif(${CMAKE_SYSTEM_NAME} STREQUAL "Zephyr")
     target_compile_definitions(lf-low-level-platform-api INTERFACE PLATFORM_ZEPHYR)

low_level_platform/api/platform/lf_nrf52_support.h

@@ -1,4 +1,4 @@
-/* nRF52832 API support for the C target of Lingua Franca. */
+/* nRF52 API support for the C target of Lingua Franca. */
 
 /*************
 Copyright (c) 2021, The University of California at Berkeley.
@@ -24,11 +24,12 @@ STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 ***************/
 
-/** nrf52 API support for the C target of Lingua Franca.
+/**
+ * nRF52 API support for the C target of Lingua Franca.
  *
- *  @author{Soroush Bateni <[email protected]>}
- *  @author{Abhi Gundrala <[email protected]>}
- *  @author{Erling Rennemo Jellum <[email protected]>}
+ * @author{Soroush Bateni <[email protected]>}
+ * @author{Abhi Gundrala <[email protected]>}
+ * @author{Erling Rennemo Jellum <[email protected]>}
  */
 
 #ifndef LF_NRF52_SUPPORT_H

low_level_platform/impl/CMakeLists.txt

@@ -22,7 +22,7 @@ elseif(${CMAKE_SYSTEM_NAME} STREQUAL "Darwin")
         ${CMAKE_CURRENT_LIST_DIR}/src/lf_macos_support.c
         ${CMAKE_CURRENT_LIST_DIR}/src/lf_atomic_gcc_clang.c
     )
-elseif(${CMAKE_SYSTEM_NAME} STREQUAL "Nrf52")
+elseif(${CMAKE_SYSTEM_NAME} STREQUAL "nRF52")
     set(LF_LOW_LEVEL_PLATFORM_FILES
         ${CMAKE_CURRENT_LIST_DIR}/src/lf_nrf52_support.c
         ${CMAKE_CURRENT_LIST_DIR}/src/lf_atomic_irq.c
@@ -45,7 +45,7 @@ elseif(${CMAKE_SYSTEM_NAME} STREQUAL "FlexPRET")
         ${CMAKE_CURRENT_LIST_DIR}/src/lf_atomic_irq.c
     )
 else()
-    message(FATAL_ERROR "Your platform is not supported! The C target supports FlexPRET, Linux, MacOS, Nrf52, RP2040, Windows, and Zephyr.")
+    message(FATAL_ERROR "Your platform is not supported! The C target supports FlexPRET, Linux, MacOS, nRF52, RP2040, Windows, and Zephyr.")
 endif()
 
 list(APPEND LF_LOW_LEVEL_PLATFORM_FILES ${CMAKE_CURRENT_LIST_DIR}/src/lf_platform_util.c)
@@ -109,7 +109,7 @@ target_link_libraries(lf-low-level-platform-impl PRIVATE lf::low-level-platform-
 target_link_libraries(lf-low-level-platform-impl PUBLIC lf-logging-api)
 
 target_compile_definitions(lf-low-level-platform-impl PUBLIC PLATFORM_${CMAKE_SYSTEM_NAME})
-message(STATUS "Applying preprocessor definitions to platform...")
+message(STATUS "Applying preprocessor definitions to low-level-platform...")
 macro(low_level_platform_define X)
     if(DEFINED ${X})
         message(STATUS ${X}=${${X}})

low_level_platform/impl/src/lf_nrf52_support.c

@@ -39,9 +39,8 @@ THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <stdio.h>
 
 #include "platform/lf_nrf52_support.h"
-#include "../platform.h"
-#include "../utils/util.h"
-#include "../tag.h"
+#include "low_level_platform.h"
+#include "tag.h"
 
 #include "nrf.h"
 #include "nrfx_timer.h"
@@ -74,9 +73,9 @@ static const nrfx_timer_t g_lf_timer_inst = NRFX_TIMER_INSTANCE(3);
 static volatile uint32_t _lf_time_us_high = 0;
 
 /**
- * Flag passed to sd_nvic_critical_region_*
+ * Flag used to count nested interrupt disables.
  */
-uint8_t _lf_nested_region = 0;
+static volatile uint8_t _lf_nested_count = 0;
 
 /**
  * @brief Handle LF timer interrupts
@@ -95,7 +94,7 @@ void lf_timer_event_handler(nrf_timer_event_t event_type, void* p_context) {
   if (event_type == NRF_TIMER_EVENT_COMPARE2) {
     _lf_sleep_interrupted = false;
   } else if (event_type == NRF_TIMER_EVENT_COMPARE3) {
-    _lf_time_us_high = +1;
+    _lf_time_us_high += 1;
   }
 }
 
@@ -193,13 +192,19 @@ static void lf_busy_wait_until(instant_t wakeup_time) {
 }
 
 /**
- * @brief Sleep until the given wakeup time. There are a couple of edge cases to consider
+ * @brief Sleep until the given wakeup time.
+ *
+ * There are a couple of edge cases to consider:
  *  1. Wakeup time is already past
  *  2. Implied sleep duration is below `LF_MAX_SLEEP_NS` threshold
  *  3. Implied sleep duration is above `LF_MAX_SLEEP_NS` limit
  *
+ * This function assumes the caller is in a critical section, so interrupts are disabled.
+ * It may exit the critical section while waiting for an event, but it will re-enter the
+ * critical section before returning.
+ *
  * @param wakeup_time The time instant at which to wake up.
- * @return int 0 if sleep completed, or -1 if it was interrupted.
+ * @return 0 if sleep completed, or -1 if it was interrupted.
  */
 int _lf_interruptable_sleep_until_locked(environment_t* env, instant_t wakeup_time) {
   instant_t now;
@@ -258,23 +263,41 @@ int _lf_interruptable_sleep_until_locked(environment_t* env, instant_t wakeup_ti
   if (!_lf_async_event) {
     return 0;
   } else {
-    LF_PRINT_DEBUG("Sleep got interrupted...\n");
+    // LF_PRINT_DEBUG("Sleep got interrupted...\n");
     return -1;
   }
 }
 
+// Definition required by sd_nvic_critical_region_enter() and exit() below.
+nrf_nvic_state_t nrf_nvic_state = {0};
+
 /**
  * @brief Enter critical section. Let NRF Softdevice handle nesting
- * @return int
+ * @return 0
  */
-int lf_enable_interrupts_nested() { return sd_nvic_critical_region_enter(&_lf_nested_region); }
+int lf_enable_interrupts_nested() {
+  if (_lf_nested_count == 0)
+    return 1; // Error. Interrupts have not been disabled.
+  _lf_nested_count--;
+  return sd_nvic_critical_region_exit(0);
+  // FIXME: If softdevice is not enabled, do the following instead of above:
+  // __enable_irq();
+  // return 0;
+}
 
 /**
  * @brief Exit citical section. Let NRF SoftDevice handle nesting
  *
  * @return int
  */
-int lf_disable_interrupts_nested() { return sd_nvic_critical_region_exit(_lf_nested_region); }
+int lf_disable_interrupts_nested() {
+  _lf_nested_count++;
+  uint8_t success = 0;
+  return sd_nvic_critical_region_enter(&success);
+  // FIXME: If softdevice is not enabled, do the following instead of the above:
+  // __disable_irq();
+  // return 0;
+}
 
 /**
  * @brief Set global flag to true so that sleep will return when woken

platform/impl/CMakeLists.txt

@@ -17,3 +17,13 @@ endif()
 add_library(lf::platform-impl ALIAS lf-platform-impl)
 target_link_libraries(lf-platform-impl PRIVATE lf::low-level-platform-api)
 target_link_libraries(lf-platform-impl PRIVATE lf::platform-api)
+message(STATUS "Applying preprocessor definitions to platform...")
+macro(platform_define X)
+    if(DEFINED ${X})
+        message(STATUS ${X}=${${X}})
+        target_compile_definitions(lf-platform-impl PUBLIC ${X}=${${X}})
+    endif(DEFINED ${X})
+endmacro()
+platform_define(LF_SINGLE_THREADED)
+platform_define(LOG_LEVEL)
+platform_define(MODAL_REACTORS)