Add memory pool

src/Pool.h

@@ -0,0 +1,56 @@
+#ifndef __POOL_H__
+#define __POOL_H__
+
+#include <cstddef>
+#include <cstdint>
+
+#include "platform/cm4/InterruptLock.h"
+
+namespace pinetime
+{
+
+template <typename T, std::size_t sizeT>
+class Pool
+{
+    union Item
+    {
+        uint8_t item[sizeof(T)];
+        Item * next;
+    };
+    Item items[sizeT];
+    uint8_t map[sizeT];
+
+public:
+    Pool()
+    {
+        for(unsigned int i = 0; i < sizeT; i++) {
+            map[i] = 0;
+        }
+    }
+
+    void *alloc()
+    {
+        pinetime::platform::cm4::InterruptLock lock;
+        void * res = nullptr;
+        for(unsigned int i = 0; i < sizeT; i++) {
+            if(map[i] == 0) {
+                map[i] = 0xff;
+                res = static_cast<void *>(items + i);
+                break;
+            }
+        }
+        return res;
+    }
+
+    void free(T * ptr)
+    {
+        pinetime::platform::cm4::InterruptLock lock;
+        // ptr is not assumed to be aligned, since the integer based aritmetic provides always the correct index and omits the ramainder.
+        std::size_t index = (reinterpret_cast<std::uintptr_t>(ptr) - reinterpret_cast<std::uintptr_t>(items)) / sizeof(Item);
+        map[index] = 0;
+    }
+};
+
+}
+
+#endif