FFI: Add 64 bit bitwise operations.

doc/ext_ffi_semantics.html

@@ -730,6 +730,22 @@ You'll have to explicitly convert a 64 bit integer to a Lua
 number (e.g. for regular floating-point calculations) with
 <tt>tonumber()</tt>. But note this may incur a precision loss.</li>
 
+<li><b>64&nbsp;bit bitwise operations</b>: the rules for 64&nbsp;bit
+arithmetic operators apply analogously.<br>
+
+Unlike the other <tt>bit.*</tt> operations, <tt>bit.tobit()</tt>
+converts a cdata number via <tt>int64_t</tt> to <tt>int32_t</tt> and
+returns a Lua number.<br>
+
+For <tt>bit.band()</tt>, <tt>bit.bor()</tt> and <tt>bit.bxor()</tt>, the
+conversion to <tt>int64_t</tt> or <tt>uint64_t</tt> applies to
+<em>all</em> arguments, if <em>any</em> argument is a cdata number.<br>
+
+For all other operations, only the first argument is used to determine
+the output type. This implies that a cdata number as a shift count for
+shifts and rotates is accepted, but that alone does <em>not</em> cause
+a cdata number output.
+
 </ul>
 
 <h3 id="cdata_comp">Comparisons of cdata objects</h3>
@@ -1222,7 +1238,6 @@ value.</li>
 Other missing features:
 </p>
 <ul>
-<li>Bit operations for 64&nbsp;bit types.</li>
 <li>Arithmetic for <tt>complex</tt> numbers.</li>
 <li>Passing structs by value to vararg C&nbsp;functions.</li>
 <li><a href="extensions.html#exceptions">C++ exception interoperability</a>

doc/extensions.html

@@ -113,6 +113,9 @@ bit.lshift bit.rshift bit.arshift bit.rol  bit.ror  bit.bswap
 This module is a LuaJIT built-in — you don't need to download or
 install Lua BitOp. The Lua BitOp site has full documentation for all
 <a href="http://bitop.luajit.org/api.html"><span class="ext">&raquo;</span>&nbsp;Lua BitOp API functions</a>.
+The FFI adds support for
+<a href="ext_ffi_semantics.html#cdata_arith">64&nbsp;bit bitwise operations<a>,
+using the same API functions.
 </p>
 <p>
 Please make sure to <tt>require</tt> the module before using any of