Minimal C thread API

Author: kjbracey

mbed.h

@@ -87,6 +87,7 @@
 #include "platform/LocalFileSystem.h"
 #include "drivers/InterruptIn.h"
 #include "platform/mbed_wait_api.h"
+#include "platform/mbed_thread.h"
 #include "hal/sleep_api.h"
 #include "platform/Atomic.h"
 #include "platform/mbed_power_mgmt.h"

platform/mbed_thread.cpp

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2019, ARM Limited, All Rights Reserved
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "platform/mbed_thread.h"
+#include "platform/mbed_critical.h"
+#include "platform/mbed_os_timer.h"
+
+/* If the RTOS is present, we call the RTOS API to do the work */
+/* If the RTOS is not present, the RTOS API calls us to do the work */
+#if MBED_CONF_RTOS_PRESENT
+#include "rtos/Kernel.h"
+#include "rtos/ThisThread.h"
+#endif
+
+extern "C" {
+
+    uint64_t get_ms_count(void)
+    {
+#if MBED_CONF_RTOS_PRESENT
+        return rtos::Kernel::get_ms_count();
+#else
+        return mbed::internal::init_os_timer()->update_and_get_tick();
+#endif
+    }
+
+    void thread_sleep_for(uint32_t millisec)
+    {
+#if MBED_CONF_RTOS_PRESENT
+        rtos::ThisThread::sleep_for(millisec);
+#else
+        // Undocumented, but osDelay(UINT32_MAX) does actually sleep forever
+        mbed::internal::do_timed_sleep_relative_or_forever(millisec);
+#endif
+    }
+
+    void thread_sleep_until(uint64_t millisec)
+    {
+#if MBED_CONF_RTOS_PRESENT
+        rtos::ThisThread::sleep_until(millisec);
+#else
+        mbed::internal::do_timed_sleep_absolute(millisec);
+#endif
+    }
+
+}

platform/mbed_thread.h

@@ -0,0 +1,67 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2019 ARM Limited
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef MBED_THREAD_H
+#define MBED_THREAD_H
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** Generic thread functions.
+ *
+ * These are C versions of functions provided in C++ via rtos::Thread and rtos::ThisThread
+ */
+
+/** Read the current RTOS kernel millisecond tick count.
+     The tick count corresponds to the tick count the RTOS uses for timing
+     purposes. It increments monotonically from 0 at boot, so it effectively
+     never wraps. If the underlying RTOS only provides a 32-bit tick count,
+     this method expands it to 64 bits.
+     @return  RTOS kernel current tick count
+     @note Mbed OS always uses millisecond RTOS ticks, and this could only wrap
+           after half a billion years.
+     @note In a non-RTOS build, this computes an equivalent time in milliseconds,
+           based on a HAL timer. The time may be referenced as 0 on first call.
+     @note You cannot call this function from ISR context.
+    @note The equivalent functionality is accessible in C++ via rtos::Kernel::get_ms_count.
+ */
+uint64_t get_ms_count(void);
+
+/** Sleep for a specified time period in millisec:
+  @param   millisec  time delay value
+  @note You cannot call this function from ISR context.
+  @note The equivalent functionality is accessible in C++ via rtos::ThisThread::sleep_for.
+*/
+void thread_sleep_for(uint32_t millisec);
+
+/** Sleep until a specified time in millisec
+  The specified time is according to Kernel::get_ms_count().
+  @param   millisec absolute time in millisec
+  @note You cannot call this function from ISR context.
+  @note if millisec is equal to or lower than the current tick count, this
+        returns immediately.
+  @note The equivalent functionality is accessible in C++ via ThisThread::sleep_until.
+*/
+void thread_sleep_until(uint64_t millisec);
+
+#ifdef __cplusplus
+}
+#endif
+
+
+#endif //MBED_THREAD_H

rtos/Kernel.cpp

@@ -26,6 +26,12 @@
 #include "platform/mbed_critical.h"
 #include "platform/mbed_os_timer.h"
 
+#if !MBED_CONF_RTOS_PRESENT
+/* If the RTOS is not present, we call mbed_thread.cpp to do the work */
+/* If the RTOS is present, mbed_thread.cpp calls us to do the work */
+#include "platform/mbed_thread.h"
+#endif
+
 namespace rtos {
 
 uint64_t Kernel::get_ms_count()
@@ -63,7 +69,7 @@ uint64_t Kernel::get_ms_count()
         return ret;
     }
 #else
-    return mbed::internal::init_os_timer()->update_and_get_tick();
+    return ::get_ms_count();
 #endif
 }
 

rtos/ThisThread.cpp

@@ -31,6 +31,10 @@
 #include "platform/mbed_os_timer.h"
 
 #if !MBED_CONF_RTOS_PRESENT
+/* If the RTOS is not present, we call mbed_thread.cpp to do the work */
+/* If the RTOS is present, mbed_thread.cpp calls us to do the work */
+#include "platform/mbed_thread.h"
+
 static uint32_t thread_flags;
 
 /* For the flags to be useful, need a way of setting them, but there's only the main
@@ -188,8 +192,7 @@ void ThisThread::sleep_for(uint32_t millisec)
     osStatus_t status = osDelay(millisec);
     MBED_ASSERT(status == osOK);
 #else
-    // Undocumented, but osDelay(UINT32_MAX) does actually sleep forever
-    mbed::internal::do_timed_sleep_relative_or_forever(millisec);
+    thread_sleep_for(millisec);
 #endif
 }
 
@@ -213,7 +216,7 @@ void ThisThread::sleep_until(uint64_t millisec)
         }
     }
 #else
-    mbed::internal::do_timed_sleep_absolute(millisec);
+    thread_sleep_until(millisec);
 #endif
 }