Function luaD_precall

third-party/lua-5.4.6/src/ldo.c:595–624

** Prepares the call to a function (C or Lua). For C functions, also do ** the call. The function to be called is at '*func'. The arguments ** are on the stack, right after the function. Returns the CallInfo ** to be executed, if it was a Lua function. Otherwise (a C function) ** returns NULL, with all the results on the stack, starting at the ** original function position. */

** original function position.
*/
CallInfo *luaD_precall (lua_State *L, StkId func, int nresults) {
 retry:
  switch (ttypetag(s2v(func))) {
    case LUA_VCCL:  /* C closure */
      precallC(L, func, nresults, clCvalue(s2v(func))->f);
      return NULL;
    case LUA_VLCF:  /* light C function */
      precallC(L, func, nresults, fvalue(s2v(func)));
      return NULL;
    case LUA_VLCL: {  /* Lua function */
      CallInfo *ci;
      Proto *p = clLvalue(s2v(func))->p;
      int narg = cast_int(L->top.p - func) - 1;  /* number of real arguments */
      int nfixparams = p->numparams;
      int fsize = p->maxstacksize;  /* frame size */
      checkstackGCp(L, fsize, func);
      L->ci = ci = prepCallInfo(L, func, nresults, 0, func + 1 + fsize);
      ci->u.l.savedpc = p->code;  /* starting point */
      for (; narg < nfixparams; narg++)
        setnilvalue(s2v(L->top.p++));  /* complete missing arguments */
      lua_assert(ci->top.p <= L->stack_last.p);
      return ci;
    }
    default: {  /* not a function */
      func = tryfuncTM(L, func);  /* try to get '__call' metamethod */
      /* return luaD_precall(L, func, nresults); */
      goto retry;  /* try again with metamethod */
    }
  }
}


/*