Re: Using pointers with inline assembly in Ada

["Jeffrey R.Carter" <spam.jrcarter.not@spam.acm.org.not>]

On 2022-06-09 23:30, 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;

Have you looked at the GNAT User's Guide section on this 
(https://docs.adacore.com/live/wave/gnat_ugn/html/gnat_ugn/gnat_ugn/inline_assembler.html)? 
I have never used this, but the first thing I notice is that the examples in the 
User's Guide put an LF-HT pair between statements:

    Asm ("pushfl"          & LF & HT & -- push flags on stack
         "popl %%eax"      & LF & HT & -- load eax with flags
         "movl %%eax, %0",             -- store flags in variable
         Outputs => Unsigned_32'Asm_Output ("=g", Flags));

It is also legal to separate the statements with spaces, but what you have would 
seem to be

    movl %0, %%eaxmovl $1, (%%eax)

which may be a problem.

-- 
Jeff Carter
"I'm a lumberjack and I'm OK."
Monty Python's Flying Circus
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