+ xo-alloc + xo-object + xo-alloc docs + GC utests

src/alloc/IAlloc.cpp

@@ -0,0 +1,54 @@
+/* @file IAlloc.cpp
+ *
+ * author: Roland Conybeare, Aug 2025
+ */
+
+#include "IAlloc.hpp"
+#include <cassert>
+#include <cstddef>
+
+namespace xo {
+    namespace gc {
+
+        std::uint32_t
+        IAlloc::alloc_padding(std::size_t z)
+        {
+            /* word size for alignment */
+            constexpr uint32_t c_bpw = sizeof(std::uintptr_t);
+
+            /* round up to multiple of c_bpw, but map 0 -> 0
+             * (table assuming c_bpw==8)
+             *
+             *   z%c_bpw   dz
+             *   ------------
+             *         0    0
+             *         1    7
+             *         2    6
+             *        ..   ..
+             *         7    1
+             */
+            std::uint32_t dz = (c_bpw - (z % c_bpw)) % c_bpw;
+            z += dz;
+
+            assert(z % c_bpw == 0ul);
+
+            return dz;
+        }
+
+        std::size_t
+        IAlloc::with_padding(std::size_t z)
+        {
+            return z + alloc_padding(z);
+        }
+
+        std::byte *
+        IAlloc::alloc_gc_copy(std::size_t /*z*/, const void * /*src*/)
+        {
+            assert(false);
+            return nullptr;
+        }
+
+    } /*namespace gc*/
+} /*namespace xo*/
+
+/* end IAlloc.cpp */