HAL_PX4: implement thread_create() API

libraries/AP_HAL_PX4/Scheduler.cpp

@@ -446,4 +446,68 @@ void PX4Scheduler::restore_interrupts(void *state)
     irqrestore((irqstate_t)(uintptr_t)state);
 }
 
+/*
+  trampoline for thread create
+*/
+void *PX4Scheduler::thread_create_trampoline(void *ctx)
+{
+    AP_HAL::MemberProc *t = (AP_HAL::MemberProc *)ctx;
+    (*t)();
+    free(t);
+    return nullptr;
+}
+
+/*
+  create a new thread
+*/
+bool PX4Scheduler::thread_create(AP_HAL::MemberProc proc, const char *name, uint32_t stack_size, priority_base base, int8_t priority)
+{
+    // take a copy of the MemberProc, it is freed after thread exits
+    AP_HAL::MemberProc *tproc = (AP_HAL::MemberProc *)malloc(sizeof(proc));
+    if (!tproc) {
+        return false;
+    }
+    *tproc = proc;
+
+    uint8_t thread_priority = APM_IO_PRIORITY;
+    static const struct {
+        priority_base base;
+        uint8_t p;
+    } priority_map[] = {
+        { PRIORITY_BOOST, APM_MAIN_PRIORITY_BOOST},
+        { PRIORITY_MAIN, APM_MAIN_PRIORITY},
+        { PRIORITY_SPI, APM_SPI_PRIORITY},
+        { PRIORITY_I2C, APM_I2C_PRIORITY},
+        { PRIORITY_CAN, APM_CAN_PRIORITY},
+        { PRIORITY_TIMER, APM_TIMER_PRIORITY},
+        { PRIORITY_RCIN, APM_TIMER_PRIORITY},
+        { PRIORITY_IO, APM_IO_PRIORITY},
+        { PRIORITY_UART, APM_UART_PRIORITY},
+        { PRIORITY_STORAGE, APM_STORAGE_PRIORITY},
+    };
+    for (uint8_t i=0; i<ARRAY_SIZE(priority_map); i++) {
+        if (priority_map[i].base == base) {
+            thread_priority = constrain_int16(priority_map[i].p + priority, 1, APM_MAX_PRIORITY);
+            break;
+        }
+    }
+    pthread_t thread;
+    pthread_attr_t thread_attr;
+    struct sched_param param;
+
+    pthread_attr_init(&thread_attr);
+    pthread_attr_setstacksize(&thread_attr, stack_size);
+
+    param.sched_priority = thread_priority;
+    (void)pthread_attr_setschedparam(&thread_attr, &param);
+    pthread_attr_setschedpolicy(&thread_attr, SCHED_FIFO);
+
+    if (pthread_create(&thread, &thread_attr, thread_create_trampoline, tproc) != 0) {
+        free(tproc);
+        return false;
+    }
+    pthread_setname_np(thread, name);
+    return true;
+}
+
 #endif

libraries/AP_HAL_PX4/Scheduler.h

@@ -10,6 +10,7 @@
 
 #define PX4_SCHEDULER_MAX_TIMER_PROCS 8
 
+#define APM_MAX_PRIORITY        243
 #define APM_MAIN_PRIORITY_BOOST 241
 #define APM_MAIN_PRIORITY       180
 #define APM_TIMER_PRIORITY      181
@@ -72,6 +73,11 @@ public:
       restore interrupt state from disable_interrupts_save()
      */
     void restore_interrupts(void *) override;
+
+    /*
+      create a new thread
+     */
+    bool thread_create(AP_HAL::MemberProc, const char *name, uint32_t stack_size, priority_base base, int8_t priority) override;
     
 private:
     bool _initialized;
@@ -115,5 +121,6 @@ private:
     perf_counter_t  _perf_io_timers;
     perf_counter_t  _perf_storage_timer;
     perf_counter_t  _perf_delay;
+    static void *thread_create_trampoline(void *ctx);    
 };
 #endif