Borland x86 inlined assembler; get a label's address?

Question

I am using Borland Turbo C++ with some inlined assembler code, so presumably Turbo Assembler (TASM) style assembly code. I wish to do the following:

void foo         


        

Answer 1

Here's a possible method:

// get_address
// gets the address of the instruction following the call
// to this function, for example
//     int addr = get_address (); // effectively returns the address of 'label'
//   label:
int get_address ()
{
    int address;
    asm
    {
        mov eax,[esp+8]
        mov address,eax
    }
    return address;
}
// get_label_address
// a bit like get_address but returns the address of the instruction pointed
// to by the jmp instruction after the call to this function, for example:
//     int addr;
//     asm
//     {
//       call get_label_address // gets the address of 'label'
//       jmp label
//       mov addr,eax
//     }
//     
//   label:
// note that the function should only be called from within an asm block.
int get_label_address()
{
    int address = 0;
    asm
    {
        mov esi,[esp+12]
        mov al,[esi]
        cmp al,0ebh
        jne not_short
        movsx eax,byte ptr [esi+1]
        lea eax,[eax+esi-1]
        mov address,eax
        add esi,2
        mov [esp+12],esi
        jmp done
    not_short:
        cmp al,0e9h
        jne not_long
        mov eax,dword ptr [esi+1]
        lea eax,[eax+esi+2]
        mov address,eax
        add esi,5
        mov [esp+12],esi
        jmp done
    not_long:
        // handle other jmp forms or generate an error
    done:
    }
    return address;
}
int main(int argc, char* argv[])
{
    int addr1,addr2;
    asm
    {
        call get_label_address
        jmp Label1
        mov addr1,eax
    }

    addr2 = get_address ();
Label1:
    return 0;
}

It's a bit hacky but it works in the version of Turbo C++ that I have. It almost certainly is dependant on the compiler and optimisation settings.