feature: implemented the luaL_checkcdataptr C API for converting LuaJIT cdata pointer object on Lua stack to pointer.

README.md

@@ -8,13 +8,15 @@ Table of Contents
 
 * [Name](#name)
 * [Description](#description)
-    * [New API](#new-api)
+    * [New Lua API](#new-lua-api)
         * [table.isempty](#tableisempty)
         * [table.isarray](#tableisarray)
         * [table.nkeys](#tablenkeys)
         * [thread.exdata](#threadexdata)
         * [table.clone](#tableclone)
         * [jit.prngstate](#jitprngstate)
+    * [New C API](#new-c-api)
+        * [luaL\_checkcdataptr](#lual_checkcdataptr)
     * [New JIT parameter defaults](#new-jit-parameter-defaults)
     * [String table hashing optimization](#string-table-hashing-optimization)
     * [New command-line option `-bL`](#new-command-line-option--bl)
@@ -31,7 +33,7 @@ since we still synchronize any upstream changes all the time.
 We introduce our own changes which will never merge or haven't yet merged into
 the upstream LuaJIT (https://github.com/LuaJIT/LuaJIT), which are as follows
 
-## New API
+## New Lua API
 
 ### table.isempty
 
@@ -161,6 +163,22 @@ the current PRNG state number used in the JIT compiler.
 
 [Back to TOC](#table-of-contents)
 
+## New C API
+
+### luaL\_checkcdataptr
+
+```C
+void *luaL_checkcdataptr(lua_State *L, int index);
+```
+
+This API allows unboxing of a cdata pointer from the Lua stack at `index`.
+Pseudo indexes such as `-1` are also supported.
+
+If the object at given `index` is not a `cdata` or is not a pointer type
+`cdata`, an error will be thrown.
+
+[Back to TOC](#table-of-contents)
+
 ## New JIT parameter defaults
 
 We use more appressive JIT compiler parameters as the default to help

src/lj_api.c

@@ -25,6 +25,9 @@
 #include "lj_vm.h"
 #include "lj_strscan.h"
 #include "lj_strfmt.h"
+#include "lj_ctype.h"
+#include "lj_lib.h"
+#include "lj_cdata.h"
 
 /* -- Common helper functions --------------------------------------------- */
 
@@ -1299,3 +1302,19 @@ LUA_API void *lua_getexdata(lua_State *L)
 {
   return L->exdata;
 }
+
+LUA_API void *luaL_checkcdataptr(lua_State *L, int idx)
+{
+  if (idx < 0) idx = lua_gettop(L) + idx + 1;
+
+  GCcdata *cd = lj_lib_checkcdata(L, idx);
+
+  if (cd->ctypeid != CTID_P_VOID &&
+      cd->ctypeid != CTID_P_CVOID &&
+      cd->ctypeid != CTID_P_CCHAR)
+  {
+    lj_err_argtype(L, idx, "cdata pointer");
+  }
+
+  return cdata_getptr(cdataptr(cd), CTSIZE_PTR);
+}

src/lua.h

@@ -248,6 +248,8 @@ LUA_API void lua_setallocf (lua_State *L, lua_Alloc f, void *ud);
 LUA_API void lua_setexdata(lua_State *L, void *exdata);
 LUA_API void *lua_getexdata(lua_State *L);
 
+LUA_API void *luaL_checkcdataptr(lua_State *L, int idx);
+
 
 /*
 ** ===============================================================