Diff: hal/mbed_critical_section_api.c

Revision:

184:08ed48f1de7f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hal/mbed_critical_section_api.c	Thu Apr 19 17:12:19 2018 +0100
@@ -0,0 +1,67 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2017 ARM Limited
+ *
+ * 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 "cmsis.h"
+#include "hal/critical_section_api.h"
+#include "platform/mbed_assert.h"
+#include "platform/mbed_toolchain.h"
+
+#include <stdbool.h>
+
+static volatile bool critical_interrupts_enabled = false;
+static volatile bool state_saved = false;
+
+static bool are_interrupts_enabled(void)
+{
+#if defined(__CORTEX_A9)
+    return ((__get_CPSR() & 0x80) == 0);
+#else
+    return ((__get_PRIMASK() & 0x1) == 0);
+#endif
+}
+
+
+MBED_WEAK void hal_critical_section_enter(void)
+{
+    const bool interrupt_state = are_interrupts_enabled();
+
+    __disable_irq();
+
+    if (state_saved == true) {
+        return;
+    }
+
+    critical_interrupts_enabled = interrupt_state;
+    state_saved = true;
+}
+
+MBED_WEAK void hal_critical_section_exit(void)
+{
+#ifndef FEATURE_UVISOR
+    // Interrupts must be disabled on invoking an exit from a critical section
+    MBED_ASSERT(!are_interrupts_enabled());
+#endif
+    state_saved = false;
+
+    // Restore the IRQs to their state prior to entering the critical section
+    if (critical_interrupts_enabled == true) {
+        __enable_irq();
+    }
+}
+
+MBED_WEAK bool hal_in_critical_section(void)
+{
+    return (state_saved == true);
+}