Re: Using pointers with inline assembly in Ada

[NiGHTS <nights@unku.us>]

On Friday, June 10, 2022 at 1:28:17 AM UTC-4, roda...@gmail.com wrote:
> On 10/6/22 07:30, NiGHTS wrote: 
> > declare 
> > type ff is array (0 .. 10) of Unsigned_32; 
> > pragma Pack(ff); 
> > Flags : aliased ff := (others => 0); 
> > Flag_Address : System.Address := Flags'Address; 
> > begin 
> > Asm ( "movl %0, %%eax" & 
> > "movl $1, (%%eax)" , 
> > Inputs => System.Address'Asm_Input ("g", Flag_Address), 
> > Clobber => "eax", 
> > Volatile => true 
> > ); 
> > Put_Line ("Output:" & Flags(0)'Img); 
> > end; 
> >
> If you are on a 64 bit machine, then I expect 'pragma Pack' might be 
> the problem, as 2 consecutive array elements will fir into a single address. 
> 
> 
> Also, possibly use ... 
> 
> Flag_Address : System.Address := Flags (Flags'First)'Address; 
> 
> 
> Regards.

Thank you for your response. Unfortunately this didn't seem to work. I agree that the pragma was misused, though that shouldn't have caused the error accessing the first element. I also am not entirely sure why there would be a difference between the address of the first element versus the address of the array itself (maybe that's just my C instincts kicking in).