keira: add Acquire and Defer classes

firmware/keira/src/utils/acquire.cpp

@@ -0,0 +1,17 @@
+#include "acquire.h"
+
+Acquire::Acquire(SemaphoreHandle_t semaphore, bool recursive) : _semaphore(semaphore), recursive(recursive) {
+    if (recursive) {
+        xSemaphoreTakeRecursive(_semaphore, portMAX_DELAY);
+        return;
+    }
+    xSemaphoreTake(_semaphore, portMAX_DELAY);
+}
+
+Acquire::~Acquire() {
+    if (recursive) {
+        xSemaphoreGiveRecursive(_semaphore);
+        return;
+    }
+    xSemaphoreGive(_semaphore);
+}

firmware/keira/src/utils/acquire.h

@@ -0,0 +1,14 @@
+#pragma once
+
+#include <FreeRTOS.h>
+#include <semphr.h>
+
+class Acquire {
+public:
+    explicit Acquire(SemaphoreHandle_t semaphore, bool recursive = false);
+    ~Acquire();
+
+private:
+    SemaphoreHandle_t _semaphore;
+    bool recursive;
+};

firmware/keira/src/utils/defer.cpp

@@ -0,0 +1,8 @@
+#include "defer.h"
+
+Defer::Defer(std::function<void()> func) : _func(func) {
+}
+
+Defer::~Defer() {
+    _func();
+}

firmware/keira/src/utils/defer.h

@@ -4,11 +4,8 @@
 
 class Defer {
 public:
-    Defer(std::function<void()> func) : _func(func) {
-    }
-    ~Defer() {
-        _func();
-    }
+    explicit Defer(std::function<void()> func);
+    ~Defer();
 
 private:
     std::function<void()> _func;