[joaquimandrade]

jim, I learnt inline assembly but I haven't solved yet completly my problem. I think now its more of a plain assembly problem.

Luckily, I reached this code to work:

PHP Code:

static cell AMX_NATIVE_CALL respawn(AMX *amx, cell *params)
{
    typedef void (*RoundRespawn)();
    RoundRespawn roundRespawn = (RoundRespawn) ResolveSig((void *)MDLL_Spawn,"RoundRespawn__11CBasePlayer");

    void *pPlayer = (void *) INDEXENT(params[1])->pvPrivateData;
    void **pPlayerPointer = &pPlayer;    

    printf(" ");

    asm ("pop %%eax":::"%eax");
    asm ("pushl %0"::"m"(pPlayerPointer));
    asm ("call %0"::"m"(roundRespawn));

    return 0;
} 


But, not only it is stupid as also if I remove the printf or the pop it crashes the server instantly. I believe that the problem is with the stack (or the lack of handling it). If you can help me out fixing the code I'll be appreciated once again.

[jim_yang]

static cell AMX_NATIVE_CALL respawn(AMX *amx, cell *params)
{
    edict_t *pEdict = MF_GetPlayerEdict(params[1]);
    void *pthis = pEdict->pvPrivateData;
    void **vtbl = *(void ***)pthis;
    void *CBasePlayer_RoundRespawn = vtbl[86];
    pEdict->v.deadflag = DEAD_RESPAWNABLE;
    pEdict->v.flags |= FL_FROZEN;
    CBasePlayer *pPlayer = (CBasePlayer *)pEdict->pvPrivateData;
    typedef void (*RoundRespawn)(CBasePlayer *);
    RoundRespawn func = (RoundRespawn)CBasePlayer_RoundRespawn;
    func(pPlayer);
    return 0;
}
static cell AMX_NATIVE_CALL respawn(AMX *amx, cell *params)
{
    edict_t *pEdict = MF_GetPlayerEdict(params[1]);
    void *pthis = pEdict->pvPrivateData;
    void **vtbl = *(void ***)pthis;
    void *CBasePlayer_RoundRespawn = vtbl[86];
    pEdict->v.deadflag = DEAD_RESPAWNABLE;
    pEdict->v.flags |= FL_FROZEN;
    reinterpret_cast<void (*)(void*)>(CBasePlayer_RoundRespawn)(pthis);
    return 0;
}

first is csdm but use vfunc not signature way
second is ham
untested
vtbl index is linux 86 for roundrespawn

[joaquimandrade]

Originally Posted by jim_yang static cell AMX_NATIVE_CALL respawn(AMX *amx, cell *params) { edict_t *pEdict = MF_GetPlayerEdict(params[1]); void *pthis = pEdict->pvPrivateData; void **vtbl = *(void ***)pthis; void *CBasePlayer_RoundRespawn = vtbl[86]; pEdict->v.deadflag = DEAD_RESPAWNABLE; pEdict->v.flags |= FL_FROZEN; CBasePlayer *pPlayer = (CBasePlayer *)pEdict->pvPrivateData; typedef void (*RoundRespawn)(CBasePlayer *); RoundRespawn func = (RoundRespawn)CBasePlayer_RoundRespawn; func(pPlayer); return 0; } static cell AMX_NATIVE_CALL respawn(AMX *amx, cell *params) { edict_t *pEdict = MF_GetPlayerEdict(params[1]); void *pthis = pEdict->pvPrivateData; void **vtbl = *(void ***)pthis; void *CBasePlayer_RoundRespawn = vtbl[86]; pEdict->v.deadflag = DEAD_RESPAWNABLE; pEdict->v.flags |= FL_FROZEN; reinterpret_cast<void (*)(void*)>(CBasePlayer_RoundRespawn)(pthis); return 0; } first is csdm but use vfunc not signature way second is ham untested vtbl index is linux 86 for roundrespawn

No jim you didn't understand me. I can call it normally. I want to call it with inline assembly so I can pass it arguments via a for loop to make it dynamic.

[jim_yang]

oh, I see.
for member function call,
push "this" to ecx,
push param_n
push param_n-1
....
push param_1
call func

for __cdecl function call
push param_n
...
push param_1
call func
add esp, 4*params

__fastcall
mov edx, param_2
mov ecx, param_1
push param_n
...
push param_n-2
call

__stdcall
push n
...
push 1
call func

only __cdecl call you should cleanup the stack yourself

[joaquimandrade]

Originally Posted by jim_yang oh, I see. for member function call, push "this" to ecx, push param_n push param_n-1 .... push param_1 call func for __cdecl function call push param_n ... push param_1 call func add esp, 4*params __fastcall mov edx, param_2 mov ecx, param_1 push param_n ... push param_n-2 call __stdcall push n ... push 1 call func only __cdecl call you should cleanup the stack yourself

This part

push "this" to ecx

i think it's only for MSVC and not for GCC. It says that in here (http://www.sourcemod.net/devlog/?p=57).

What I'm puzzled about is why in that code above with inline assembly i've posted I can't remove the printf and the pop from there.

[jim_yang]

I've read an article about linux member function call, but I've forgot if it pass the "this" pointer through ecx, seems only vc use that

[joaquimandrade]

Ok thanks

[jim_yang]

you can try this
void *pthis = ENTINDEX(params[1])->pvPrivateData;
push pthis;
call func;
add esp, 4;

[joaquimandrade]

Originally Posted by jim_yang you can try this void *pthis = ENTINDEX(params[1])->pvPrivateData; push pthis; call func; add esp, 4;

I've tried

PHP Code:

asm ("pushl %0"::"m"(pPlayerPointer));
asm ("call %0"::"m"(roundRespawn));
asm ("addw 4, %esp"); 


and

PHP Code:

asm ("pushl %0"::"m"(pPlayerPointer));
asm ("call %0"::"m"(roundRespawn));
asm ("addl 4, %esp"); 


and both crash. Btw, addw stands for "add word" and addl stands for "add long". But if i'm correct registers are words so it should be addw. I'm gonna keep trying if you remember more things to try please let me know.

One question: do I have to clean the stack before executing this assembly code? Or just after?

[jim_yang]

after, you push a param stack -= 4, so you should add esp, 4 after call it

by the way
do you use void **pPlayerPointer, it should be void *pPlayerPointer = ent->pvPrivateDate;