Added derivation of TDF base class, for AVR8 targets.

Includes initialisation and validation code.

build/scripts/TargetDescriptionFiles/AddressSpace.php

@@ -0,0 +1,15 @@
+<?php
+namespace Bloom\BuildScripts\TargetDescriptionFiles;
+
+require_once __DIR__ . "/MemorySegment.php";
+
+class AddressSpace
+{
+    public ?string $id = null;
+    public ?string $name = null;
+    public ?int $startAddress = null;
+    public ?int $size = null;
+
+    /** @var MemorySegment[][] */
+    public array $memorySegmentsByTypeAndName = [];
+}