Make bit module handle 32/64bit integer configs.

components/lua/lua-5.1/luaconf.h

@@ -169,7 +169,7 @@
 
 /* Changed to long for use with integral Lua numbers. */
 #if !defined LUA_NUMBER_INTEGRAL
-#define LUA_INTEGER ptrdiff_t
+#define LUA_INTEGER int
 #else
   #if !defined LUA_INTEGRAL_LONGLONG
   #define LUA_INTEGER	int

components/modules/bit.c

@@ -10,9 +10,11 @@
 
 #include "lauxlib.h"
 
-/* FIXME: Assume size_t is an unsigned lua_Integer */
-typedef size_t lua_UInteger;
-#define LUA_UINTEGER_MAX SIZE_MAX
+#if defined(LUA_UNSIGNED)
+typedef LUA_UNSIGNED lua_UInteger;
+#else
+typedef unsigned LUA_INTEGER lua_UInteger;
+#endif
 
 /* Define TOBIT to get a bit value */
 #define TOBIT(L, n)                    \

docs/modules/bit.md

@@ -4,7 +4,9 @@
 | 2014-12-24 | [https://github.com/LuaDist/bitlib](https://github.com/LuaDist/bitlib), [Zeroday](https://github.com/funshine) | [Zeroday](https://github.com/funshine) | [bit.c](../../components/modules/bit.c)|
 
 
-Bit manipulation support, on 32bit integers.
+Bit manipulation support, on the integer type used by the Lua VM. On 5.1 this
+will be 32bit, whereas on 5.3 it may be either 32bit (default) or 64bit if
+configured for 64bit integers.
 
 ## bit.arshift()
 Arithmetic right shift a number equivalent to `value >> shift` in C.