Function luaD_precall

Source/Misc/lua/src/lua.c:5410–5474

int luaD_precall (lua_State *L, StkId func, int nresults) {
LClosure *cl;
ptrdiff_t funcr;
if (!ttisfunction(func)) /* `func' is not a function? */
func = tryfuncTM(L, func);  /* check the `function' tag method */
funcr = savestack(L, func);
cl = &clvalue(func)->l;
L->ci->savedpc = L->savedpc;
if (!cl->isC) {  /* Lua function? prepare its call */
CallInfo *ci;
StkId st, base;
Proto *p = cl->p;
luaD_checkstack(L, p->maxstacksize);
func = restorestack(L, funcr);
if (!p->is_vararg) {  /* no varargs? */
base = func + 1;
if (L->top > base + p->numparams)
L->top = base + p->numparams;
}
else {  /* vararg function */
int nargs = cast_int(L->top - func) - 1;
base = adjust_varargs(L, p, nargs);
func = restorestack(L, funcr);  /* previous call may change the stack */
}
ci = inc_ci(L);  /* now `enter' new function */
ci->func = func;
L->base = ci->base = base;
ci->top = L->base + p->maxstacksize;
lua_assert(ci->top <= L->stack_last);
L->savedpc = p->code;  /* starting point */
ci->tailcalls = 0;
ci->nresults = nresults;
for (st = L->top; st < ci->top; st++)
setnilvalue(st);
L->top = ci->top;
if (L->hookmask & LUA_MASKCALL) {
L->savedpc++;  /* hooks assume 'pc' is already incremented */
luaD_callhook(L, LUA_HOOKCALL, -1);
L->savedpc--;  /* correct 'pc' */
}
return PCRLUA;
}
else {  /* if is a C function, call it */
CallInfo *ci;
int n;
luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
ci = inc_ci(L);  /* now `enter' new function */
ci->func = restorestack(L, funcr);
L->base = ci->base = ci->func + 1;
ci->top = L->top + LUA_MINSTACK;
lua_assert(ci->top <= L->stack_last);
ci->nresults = nresults;
if (L->hookmask & LUA_MASKCALL)
luaD_callhook(L, LUA_HOOKCALL, -1);
lua_unlock(L);
n = (*curr_func(L)->c.f)(L);  /* do the actual call */
lua_lock(L);
if (n < 0)  /* yielding? */