+ docs in xo-alloc2/ + misc improvements

docs/DArena-reference.rst

@@ -0,0 +1,64 @@
+.. _DArena-reference:
+
+DArena Reference
+================
+
+Native representation for arena allocator
+
+Context
+-------
+
+.. ditaa::
+    :--scale: 0.99
+
+    +--------------------------------+
+    |      IAllocator_DArena         |
+    +--------------------------------+
+    |      IAllocator_Xfer           |
+    +--------------------------------+
+    |      IAllocator_ImplType       |
+    +--------------+-----------------+
+    |              |    DArena   cBLU|
+    |   AAllocator +-----------------+
+    |              | ArenaConfig     |
+    +--------------+-----------------+
+
+.. code-block:: cpp
+
+    #include <xo/alloc2/DArena.hpp>
+
+
+Arena memory layout::
+
+    <----------------------------size-------------------------->
+    <------------committed-----------><-------uncommitted------>
+    <--allocated-->
+
+    XXXXXXXXXXXXXXX___________________..........................
+   ^               ^                  ^                         ^
+   lo              free               limit                     hi
+
+    [X] allocated:   in use
+    [_] committed:   physical memory obtained
+    [.] uncommitted: mapped in virtual memory, not backed by memory
+
+
+Class
+-----
+
+.. doxygenclass:: xo::mm::DArena
+
+Member Variables
+----------------
+
+.. doxygengroup:: mm-arena-instance-vars
+
+Type Traits
+-----------
+
+.. doxygengroup:: mm-arena-traits
+
+Constructors
+------------
+
+.. doxygengroup:: mm-arena-ctors