compiles with -betterC -m32

module runnable;

__gshared static msg = "betterC";
__gshared static len = 7;

extern(C) int main(int argc, char** args)
{
    asm
    {
        naked;
        mov EDX, len ;//message length
        mov ECX, msg ;//message to write
        mov EBX, 1   ;//file descriptor (stdout)
        mov EAX, 4   ;//system call number (sys_write)
        int 0x80     ;//call kernel

        mov EBX, 0   ;//process' exit code
        mov EAX, 1   ;//system call number (sys_exit)
        int 0x80     ;//call kernel - this interrupt won't return
    }
}

nothing is printed. Could this work ?

On Saturday, 3 February 2018 at 15:30:10 UTC, Basile B. wrote:
> __gshared static msg = "betterC";

That's a D string....

>         mov ECX, msg ;//message to write

And that's the address of a D string, instead of the address of the characters.

You need to put the pointer in there. So either make msg a char*, or pass msg.ptr there. With inline asm the ptr word will cause weirdness so I tend to move the pointer and length into local variables first.

On Saturday, 3 February 2018 at 15:30:10 UTC, Basile B. wrote:
> compiles with -betterC -m32
>
> module runnable;
>
> __gshared static msg = "betterC";
> __gshared static len = 7;
>
> extern(C) int main(int argc, char** args)
> {
>     asm
>     {
>         naked;
>         mov EDX, len ;//message length
>         mov ECX, msg ;//message to write
>         mov EBX, 1   ;//file descriptor (stdout)
>         mov EAX, 4   ;//system call number (sys_write)
>         int 0x80     ;//call kernel
>
>         mov EBX, 0   ;//process' exit code
>         mov EAX, 1   ;//system call number (sys_exit)
>         int 0x80     ;//call kernel - this interrupt won't return
>     }
> }
>
> nothing is printed. Could this work ?

okay solved:



module runnable;

__gshared static msg = "betterC\n";
__gshared static len = 8;

extern(C) int main(int argc, char** args)
{
    asm
    {
        naked;
        mov EDX, len ;//message length
        mov ECX, [msg + 4] ;//message to write
        mov EBX, 1   ;//file descriptor (stdout)
        mov EAX, 4   ;//system call number (sys_write)
        int 0x80     ;//call kernel

        mov EBX, 0   ;//process' exit code
        mov EAX, 1   ;//system call number (sys_exit)
        int 0x80     ;//call kernel - this interrupt won't return
    }
}

the pointer to the string data is 4 bytes later...

On Saturday, 3 February 2018 at 15:38:02 UTC, Adam D. Ruppe wrote:
> On Saturday, 3 February 2018 at 15:30:10 UTC, Basile B. wrote:
>> __gshared static msg = "betterC";
>
> That's a D string....
>
>>         mov ECX, msg ;//message to write
>
> And that's the address of a D string, instead of the address of the characters.
>
> You need to put the pointer in there. So either make msg a char*, or pass msg.ptr there. With inline asm the ptr word will cause weirdness so I tend to move the pointer and length into local variables first.

Yeah, I forgot the ABI. It's working well

https://forum.dlang.org/post/edjipahtfphiqmxsiioq@forum.dlang.org

On Saturday, 3 February 2018 at 15:38:19 UTC, Basile B. wrote:
> On Saturday, 3 February 2018 at 15:30:10 UTC, Basile B. wrote:
>> [...]
>
> okay solved:
>
>
>
> module runnable;
>
> __gshared static msg = "betterC\n";
> __gshared static len = 8;
>
> extern(C) int main(int argc, char** args)
> {
>     asm
>     {
>         naked;
>         mov EDX, len ;//message length
>         mov ECX, [msg + 4] ;//message to write
>         mov EBX, 1   ;//file descriptor (stdout)
>         mov EAX, 4   ;//system call number (sys_write)
>         int 0x80     ;//call kernel
>
>         mov EBX, 0   ;//process' exit code
>         mov EAX, 1   ;//system call number (sys_exit)
>         int 0x80     ;//call kernel - this interrupt won't return
>     }
> }
>
> the pointer to the string data is 4 bytes later...

[msg] contains the length of the string, so there's no need of your len variable. Just saying.